VE coming out way over 100

[Mastiff]

I'm really bummed. My engine would not tune and had a terrible off-idle hesitation. I discovered fluctuating fuel pressure and air getting into the fuel lines with the in-line pump. Since the tank had to be replaced anyway for another reason, I went to a bone stock in-tank fuel pump setup (copying a 1991 Blazer). This is for a GM TBI 7747. Fired it up today and started tuning. First of all, the hesitation is not gone. But, maybe it just needs a tune. Thing is, the first time out I came back to adjust the VE and I have values as high as 112. And this is with the BPW already bumped up from 135 to 150. The BIN I'm starting with is ARJT, which I adjusted so that the VE2 table is zeroed out - just to make the tuning easier.

One thing is that the 135 BPW seems to come from a nominal fuel pressure of 12 PSI. My fuel pressure is steady at 9-10 PSI. Just working the math, this would seem to want to push the BPW up to about 180, all else equal. The only major mod to my engine is headers, but that might push the efficiency up a little. I don't mind trying the 180, but it makes me wonder how this ever worked in the factory. The VE table doesn't seem to have enough range to soak up any fuel pressure variation at all. I've read that any VE over 100 will just limit to 100, even if it's the combination of VE1 and VE2.

[EagleMark]

I've tuned a lot of 1227747 and if it doesn't have 13 PSI it'll never run right. Yes GM says between 9 and 13 psi and it will run there. But if you want it to run right you need 13 PSI. Injectors are also an issue at this age. Last set I had serviced gained 9 and 13 persent to come out almost a perfect match.

Battery voltage also plays a role in fuel pressure as well as ECM function. I know this is a conversion on your truck so you have an older altenater that usually does not keep voltage in the 13.5 to 14.2 range at idle, I've seen some creep down past the 12 volt mark at idle which causes all sorts of issues, so give that a check and rev engine, watch voltage and see what kind of fuel pressure you get when it's charging. Fuel pump ground can also be an issue with low pressure, ECM grounding to block, block to frame where fuel pump ground is usually located.

I've heard a lot of people 0 out VE2 and add it to VE1 but you need to leave the number in 0 RPM in VE2. That said, I have never done this. I always leave VE2 alone and tune VE1 and I get results in tables that add over 100. Why? I don't know but it works. Although I have been told by the most intellegent EFI person I know that this was a GM mistake. But it works for me?

There is also and issue with BPW over 150... I wish I could remember what it is but it's been so long I forget? I never try to go above that, if I need more I raise fuel pressure.

HTH! :rockon:

[dave w]

When I have a VE cell of 100 or more, I increase the BPW. I'm in the camp of tuners that will add VE1 and VE2, which is a personal preference.

dave w

[EagleMark]

We talked about this before, what about 1227747 that VE1 and VE2 already add up to over 100 on stock chip?

I agree with you on the 100 Dave! But factory is already beyound that and I have got more out of it. Why?

But his motor is stock and already can't get enough VE but with 9 - 10 PSI I think fuel pressure is his issue...

[PJG1173]

I know when I first started messing with truck my fuel pressure was 9psi. after putting a TBI rebuild kit in with new diapham for the FPR I gained almost 3 psi before I made it adjustable.

[Mastiff]

I think we're just going on comments from thirdgen that VE1+VE2 greater than 100 gets clipped at 100 within the computer. I'm not sure why GM developers would go to the trouble to limit system flexibility like that though, unless it was some sort of safety thing for runaway BLM. Tunerpro definitely cuts off VE at 100 within any one table.

I like the voltage idea. I'm going to check that next. I do seem to recall my voltage dropping down at idle sometimes. This could explain a lot, but doesn't the ECM measure the voltage and compensate for it in the sensors? The main thing would be fluctuating pressure right from the pump at lower voltages I guess, but if the regulator can't get what it wants even at idle that seems weird...

[rokcrawlin85]

just thinking here, how far off are your BLM's with the latest tune you've done to the VE tables?

[Mastiff]

just thinking here, how far off are your BLM's with the latest tune you've done to the VE tables?

Well, I didn't actually adjust them when I saw a bunch of the values saturating at 100%. The BLM's for the first run were 150-160 type range mostly. that was with BPW of 150. If I did my math right, that's about 35% above nominal (128 BLM and 135 BPW). I guess that's not unreasonable since just the fuel pressure alone is 33% (9/12).

[1project2many]

I think we're just going on comments from thirdgen that VE1+VE2 greater than 100 gets clipped at 100 within the computer. I'm not sure why GM developers would go to the trouble to limit system flexibility like that though, unless it was some sort of safety thing for runaway BLM. Tunerpro definitely cuts off VE at 100 within any one table.

Why would they do this? They're not limiting system flexibility. They're engineers and they know VE isn't going to exceed 100% on a stock N/A engine. If you're trying add fuel so you have greater than 100% then you've got the wrong injectors, or wrong fuel pressure, or wrong BPW constant. If you're over 100% then you're *at* 100%. As long as the injector duty cycle isn't exceeding 80% you can change the BPW, scale your tables down, and commence further tuning.

[dave w]

We talked about this before, what about 1227747 that VE1 and VE2 already add up to over 100 on stock chip?

I agree with you on the 100 Dave! But factory is already beyound that and I have got more out of it. Why?

But his motor is stock and already can't get enough VE but with 9 - 10 PSI I think fuel pressure is his issue...

Very seldom do I tune a "Just Stock Engine". I really don't know what is actually happening in the 1227747 ECM when the VE values exceed 100 (with VE1 added with VE2). I base my input on real world tuning experiences, others usually experience similar results when using same tuning practices. A very long time ago, back in the 70's, Hot Rod Magaizine had a tech section called, "It worked for Me". Keeping the VE tables values (with VE1 added with VE2) of a 122774 between 40 ~ 95 has always worked for me.:thumbsup:

The basics of tuning must be verified; good sound mechanical condition of the engine, good sensors, good fuel, and good fuel pressure are a must before attempting to tune a chip.

dave w

[rokcrawlin85]

The basics of tuning must be verified; good sound mechanical condition of the engine, good sensors, good fuel, and good fuel pressure are a must before attempting to tune a chip.

dave w

spot on i'd say... make sure your connections are solid and that the voltage is good. If still no change, raise the fuel pressure to 15 psi. if your BLM's are still not dropping, i'd lean toward that your injectors are fully maxed out or they're going bad/faulty. Like project said i'd try to keep your duty cycle around the 80% mark at its max, not by just changing the BPW, if your injectors have no more in them, you can't get anymore out of them.

[Mastiff]

How can you know what the duty cycle is?

[EagleMark]

It's in the data stream on many 8192 baud rate systems, but I don't recall seeing it in any 160 Baud data stream like the 1227747...

[EagleMark]

They're engineers and they know VE isn't going to exceed 100% on a stock N/A engine. Well they sure wern't paying attention when they did the 1227747 $42 bins...

Unless there is something else in the bin that is calculating this differantly?

The 1228746 $61 has VE1 and VE2 adder and it does not go over 100, high ones stop at 90ish

[RobertISaar]

duty cycle isn't directly reported by any ECM, it's created in tunerpro taking the BPW and RPM variables to make a DC.

[EagleMark]

I stand corrected... but there's no BPW in this data stream....

[Mastiff]

duty cycle isn't directly reported by any ECM, it's created in tunerpro taking the BPW and RPM variables to make a DC.

You're saying there's a tool in tunerpro that will compute my duty cycle for me? How do I find that?

[RobertISaar]

You're saying there's a tool in tunerpro that will compute my duty cycle for me? How do I find that?

not a tool, it's a value you create while editting an ADX. however, as Mark pointed out, the ECM doesn't transmit a BPW value.

i imagine you could hack the datastream though, and replace PROM ID with the injected BPW... just a thought. that is if that is kept on the replaceable PROM and not the other one. (i'm really in the dark on C3s.)

[gregs78cam]

i imagine you could hack the datastream though, and replace PROM ID with the injected BPW... just a thought.

I do this a lot in the '7427.

[EagleMark]

(i'm really in the dark on C3s.)It's like 10% of nAst1...

Create a value in adx file and use BPW (x) times RPM (y) as a linked output with conversion of X*Y/60000*100

But 1227747 does not have BPW in data stream, just looked at a couple other 160 Baud C3 ECM and none there either...

[EagleMark]

I do this a lot in the '7427.And one day your going to give us a lesson? :happy:

[RobertISaar]

yeah, i've completely reorganized/added/sub'd/etc from the A1 stream when i made it nAst1 to get rid of all of the useless crap, add in interesting stuff, etc...

however, i know next to nothing about the C3 and am not sure of how simple it is on those compared to the P4 units.

[gregs78cam]

And one day your going to give us a lesson? :happy:

Thread on it's way.

[EagleMark]

yeah, i've completely reorganized/added/sub'd/etc from the A1 stream when i made it nAst1 to get rid of all of the useless crap, add in interesting stuff, etc...

however, i know next to nothing about the C3 and am not sure of how simple it is on those compared to the P4 units.I do remeber seeing the XDF side of nAst1 but not the ADX side... the XDF was quite impressive!

[RobertISaar]

I do remeber seeing the XDF side of nAst1 but not the ADX side... the XDF was quite impressive!

the nAst1 project is the culmination of my entire coding knowledge combined with 3 years of being unemployed that i've more or less devoted to learning as many different things as possible.

and to think, it's nowhere near done. the longest term goal is closed loop control of the VVT used on the gen4 60V6 motors (3500/3900).

[Mastiff]

Guys, I'm so confused. I've got my BPW all the way up to 200 and the BLMs are still high. I saw change in the area around idle, but other areas still climb up to 160-170. Funny thing is that it drives okay. You'd think a ridiculous BPW like that would mess it up. My only guess now is that the pressure regulator is shot and I'm chasing my tail trying to make up for low pressure. Maybe the cells that won't lower with BPW are going static. Do FPRs just go bad sometimes?

When I first fired up the truck, the gauge read 11 PSI. When I stopped driving it was reading about 8 PSI, but everyone says the underhood liquid filled gauges read low when hot, so that might not mean anything. I don't have a way to see the fuel pressure while driving.

[EagleMark]

Unless you have a bad gauge that is BS!!!

You just proved what I said all along is you don't have enough fuel pressure. You got everything turned up so high you got idle OK but not under load. That is not enough fuel!

Yes regulater diaphrams go bad and the springs crack!

Pinch your return line and see how high pressure goes?

[JeepsAndGuns]

Pinch your return line and see how high pressure goes?

I might actually advise not to do that if you have a low pressure gauge installed! I had a 0-20 psi gauge installed in a T inline to the TB, I was adjusting my FPR to get my pressure up and the max I could get was 13psi. I grabbed some plires and pinched off the return line for just a second and the gauge instantly pegged, and ever since doing that, the needle stopped moving. It just stuck in the middle of the gauge and wouldnt move. I broke it....:laugh: I had to go buy a new gauge.

[Mastiff]

I'm going to assume the FPR is bad. What should I buy for a replacement? If I just buy a factory replacement I might end up at 9 PSI. Adjustable is probably my best bet, which one should I get?

[EagleMark]

I might actually advise not to do that if you have a low pressure gauge installed! I had a 0-20 psi gauge installed in a T inline to the TB, I was adjusting my FPR to get my pressure up and the max I could get was 13psi. I grabbed some plires and pinched off the return line for just a second and the gauge instantly pegged, and ever since doing that, the needle stopped moving. It just stuck in the middle of the gauge and wouldnt move. I broke it....:laugh: I had to go buy a new gauge. :yikes:
OK I should revise my statement to slowly pinch return line and watch pressure rise! :thumbsup:


I'm going to assume the FPR is bad. What should I buy for a replacement? If I just buy a factory replacement I might end up at 9 PSI. Adjustable is probably my best bet, which one should I get?Do the test and make sure it is not fuel pump related first. Then a TBI rebuild kit would have the diaphragm. You may have a broken spring.

You can make your regulator adjustable by drilling out the filling in hole on bottom of regulator. There is a screw in there but if you drill to far you ruin the screw, you can cut a slot in screw to turn with screw driver or find replacement.
http://www.thirdgen.org/tbi-afpr

If you do this leave injector pod off TBI and hook it to your fuel line with pressure gauge in. Turn key on, no start and watch pressure, you only get 2 seconds, or if your fuel pump relay still had a red wire you can power it to run fuel pump and set pressure. Even if you buy an adjustable regulator do this as they are a pain if not impossible to do on TBI. There is one cool one I have seen that has a long knob coming down below throttle body so it can be turned easily while installed, but I forget who makes it.

[1project2many]

Unless you have a bad gauge that is BS!!!

You just proved what I said all along is you don't have enough fuel pressure (http://shop.ebay.com/i.html?_nkw=fuel+pressure). You got everything turned up so high you got idle OK but not under load. That is not enough fuel!

Yes regulater diaphrams go bad and the springs crack!

Pinch your return line and see how high pressure goes?



Check fuel filter??

[Mastiff]

Thing is, the symptoms aren't so different from before I replaced EVERYTHING on the fuel delivery side. The pump is new, most of the lines are new, the filter is new, and it's all stock (EFI fuel filter, etc.). Anything is possible, but FPR seems like my best bet. I'll replace that and see what happens. Next step is to get real time fuel pressure into the cab. That stuff's not cheap.

[EagleMark]

I agree. But new parts do not mean good properly working parts!

And if you pinch return line carefully and pressure goes through the roof you know for sure it's the regulator.

You can also make and adpater with long hose from your fitting at TBI and run the gauge up under windsheild wiper to watch WOT fueling. Once your done and confident it will be fine and you save hundreds of dollars for in cab fuel pressure gauge.

[gregs78cam]

You can also make and adpater with long hose from your fitting at TBI and run the gauge up under windsheild wiper to watch WOT fueling. Once your done and confident it will be fine and you save hundreds of dollars for in cab fuel pressure gauge.

That's how I found my lagging regulator, had to move it closer to TBI.

[JeepsAndGuns]

I guess I'm the only one who that gauge on a long line doesnt work. I tried that, got a T fitting and ran a hose through a hole in the firewall and hooked to the gauge. When I started it, it only read a couple psi, took the line loose and put the gauge right in the T and it read the correct pressure. Put it back on the long hose and only got a couple psi. I tried bleeding the line of air and it made no diffrence other than getting gas everywhere. It just didnt ever work.

[EagleMark]

that's strange? Even my tool gauge has about 12 inches of hose...

[Mastiff]

Well, I pinched the hose and it flew up over 15. I didn't push it anymore. I took apart the FPR and the spring is rusty and the diaphragm ratty and rust, but it all looks functional. I replaced it anyway and it made no difference. The rebuild kit came with a few sponge rubber rings. They weren't on the exploded view anywhere. Anyone know what they are? I didn't see anything like them in there.

I'm attaching a picture of the insanity I'm up against. I'm running out of ideas. Let me ask this: how hot does an engine need to be to overload the factory setup? This motor is not factory. I don't think of it as heavily built up, but it has the headers, Edelbrock intake, maybe a slightly hotter cam than factory. Could I be going static, even at low RPM?

[gregs78cam]

Maybe leave VE1 as is, and fill VE2 back in like stock? Just a thought.


I've heard a lot of people 0 out VE2 and add it to VE1 but you need to leave the number in 0 RPM in VE2. That said, I have never done this. I always leave VE2 alone and tune VE1 and I get results in tables that add over 100. Why? I don't know but it works.

[dave w]

Well, I pinched the hose and it flew up over 15. I didn't push it anymore. I took apart the FPR and the spring is rusty and the diaphragm ratty and rust, but it all looks functional. I replaced it anyway and it made no difference. The rebuild kit came with a few sponge rubber rings. They weren't on the exploded view anywhere. Anyone know what they are? I didn't see anything like them in there.

I'm attaching a picture of the insanity I'm up against. I'm running out of ideas. Let me ask this: how hot does an engine need to be to overload the factory setup? This motor is not factory. I don't think of it as heavily built up, but it has the headers, Edelbrock intake, maybe a slightly hotter cam than factory. Could I be going static, even at low RPM?

I'm thinking maybe for the time being, let's assume the fuel system is OK. I'm wondering about the O2 voltages? The O2 volts are used by the ECM to calculate the BLM's I like the heated 3-wire O2 sensor with headers.

dave w

[EagleMark]

The rubber sponge goes under the regulator to seal off air coming into engine from underneath (un filtered air).

Your specs on engine are no where near these issues. Unless you have wrong injectors. But.............. wait for it......................














Your fuel pressure is to low!!!!! :mad1:

Something is wrong with the way your regulator is set or your spring is bad. Since you have to take it off and put the sponge in put a new spring in, or new spring with adjustable regulator, or at least scratch the spring by a third.

But you could also do a test for us. Put 25.00 in VE2 RPM 0 column and re-datalog to compare. I've read that needs to be there. Why? I don't know or remember because I never do this. You could also do a test by going back to stock VE1 and VE2 for another test. These tests help us all learn! :thumbsup:

This would also rule out your Fuel Pressure Gauge being inaccurate!

[Mastiff]

I'm not sure I understand about the sponge thing. The kit has two of them by the way, one big and one small. Do you mean it goes outside the regulator assembly on the bottom? If I'm thinking of it right, I could do that without taking it all apart. The kit did come with a new spring, which I installed.

Are you saying 11 PSI is not enough to tune the engine? I could pull the pod off and tighten up the spring some... It looks like a person could bend the tab, rotate the cup a few times and bend it back out. Is that right?

I do have a 3-wire heated O2 also.

I'll try the stock bin and putting 25 in RPM 0. I'll be surprised if it matters, but it's pretty easy to do.

[EagleMark]

I don't know why there are 2 sponges? One goes under center of regulator, I am looking at one right now and you will have to remove injector pod to get it down in hole. Now if one is a little bigger it looks like it could go on regulator above that. But again injector pod is going to have to come off.

Your up to 11 psi and saw no difference? I thought you were still at 9 psi? Up 2 more PSI to 13 is still a lot of fuel! 11 PSI is getting close to some gauges that are not accurate. What is the scale on your gauge? 0 to 15 is way more accurate then say 0 to 60...

I never though about bending the tab and giving it a couple turns tighter?

Is your O2 sensor clean on outside? Have you pulled it to see if it's sooted up? Did that old motor ever use non O2 sensor safe gasket sealer/silicone? You could read the O2 sensor thread for testing procedure on it.

Pull a couple plugs and see what color they are?

I'm really curious of those 2 tests if you have time before making any more changes?

[EagleMark]

I missed dave w post on O2, but I was thinking same thing...

[Mastiff]

Here's a picture of the kit I got:

http://images.oreillyauto.com/parts/img/medium/bwd/21732_1.jpg

I guess I wasn't clear I always had 11 PSI when I first fired up. After it was hot, it read 9 PSI. I was reading a thread on thridgen that said the underhood liquid filled gauges were notorious for reading way low once hot, so to just pay attention to the cold readings. Both FPRs had this same behavior. I can't remember my full range, but it would be in the neighborhood of 50 PSI.

Yeah, I was looking at the FPR and there has to be some reason for the threaded rod, cup, tab, etc. That's all I could think of. If they didn't intend for it to adjust, why not just have a fixed cup and be done with it...

I haven't pulled the O2 in a long time. I don't think I ever put any silicone on it or anything. I did verify it's getting voltage to the heat wire and that the ground was good.

The thing that confuses me is, if it's not a fuel pressure problem, where is all that fuel going? If the O2 was bad, I;m still dumping 200 BPW with 172 BLM worth of fuel into the thing and it runs decent and doesn't stink like gas. How is that possible? I passed emissions with it like this too. It almost HAS to be a fuel pressure thing, but I don't know how.


I don't know why there are 2 sponges? One goes under center of regulator, I am looking at one right now and you will have to remove injector pod to get it down in hole. Now if one is a little bigger it looks like it could go on regulator above that. But again injector pod is going to have to come off.

Your up to 11 psi and saw no difference? I thought you were still at 9 psi? Up 2 more PSI to 13 is still a lot of fuel! 11 PSI is getting close to some gauges that are not accurate. What is the scale on your gauge? 0 to 15 is way more accurate then say 0 to 60...

I never though about bending the tab and giving it a couple turns tighter?

Is your O2 sensor clean on outside? Have you pulled it to see if it's sooted up? Did that old motor ever use non O2 sensor safe gasket sealer/silicone? You could read the O2 sensor thread for testing procedure on it.

Pull a couple plugs and see what color they are?

I'm really curious of those 2 tests if you have time before making any more changes?

[PJG1173]

read your plugs lately?

[Mastiff]

Changing them is on my list. I can't imagine plugs alone could cause all this, but what do I know...

[EagleMark]

Yeah those 2 sponges are for the regulator cup bottom to seal off air from being drawn into TBI. I don't recall those 2 silver rod things? What were they for?

I've had 2 cheap liguid fuel pressure gauges from Summit and never an issue hot, worked on a few and same thing. But none on a Camaro so maybe it's a Thirdgen thing?

If your gauge is 0 to 50 and reading 11 it could be close enough. You understand why a 0 to 15 pound gauge would/should be more accurate because of the amount of swing...

IIRC you had an inline pump and same pressure or same lean BLM? But we saw bubbles in clear pre-filter pump and beleived it was sucking air. Now you changed out to newer style tank with in tank pump and still have same fuel pressure and lean BLM?

I try to help a lot of people and loose track so forgive me... if all that is correct what part in middle of fuel system is still the same? Could there be a pinched line on feed side? Pump is now in tank so there's no sucking air between tank and pump... I'm assuming there's no issue with intank pump installation... in-tank pump ground is good... tank was clean as you just put it in...

So on to what dave w and I mentioned with O2 sensor. I would pull it and see if it is sooted up black and then test or replace. Here's an article on how to test:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?82-Good-read-on-O2-sensors

and as mentioned pul a couple plugs and see if they are white. If your that lean they will be white. Tan is good. Black is rich.

At this point I'm assuming again you have no cylinders not firing (miss) and no exhaust leaks before O2 sensor. Would have to be a big vacuum leak on intake side messing up O2 reading... with that said I would pull all four plugs on O2 sensor side of engine...

Wish you were closer and I could get my hands on it, I actully enjoy diagnosis...

Any other ideas I'm missing here guys?

[EagleMark]

Changing them is on my list. I can't imagine plugs alone could cause all this, but what do I know...It's not the changing it's looking at them/reading them!

[Mastiff]

You are correct about the things I have done. The only thing that is the same on the fuel feed side is a section of factory steel line on the frame that I've been using. All the rubber line is new and the filter is new. If you recall, it was a cheesy carb filter with air in it and now it's an EFI filter (factory style 1991 K5). I'd be surprised if the plugs were crazy, but I'll look. The computer is trying to pull it in, and it runs okay except for terrible hesitation on acceleration, especially cold. If not for that, a person wouldn't know anything was wrong without reading the numbers. So, on my list so far:

1) Try the unmolested ARJT bin
2) Try just putting the 25 back in 0 RPM
3) Check the plugs
4) Check the O2 sensor
5) See about getting fuel pressure into the cab
6) Buy EBL for better overall instrumentation - ha!

[EagleMark]

Since you've done about everything on fuel side you should inspect that steel fuel line for a pinch. Your getting enough fuel to get close pressure and BLM at idle close but goes downhill when it needs more fuel. If it's got a kink or pinch or damage from off road it will limit supply.

Computer is trying to compensate for something?

I'd never try and talk someone out of EBL but it will not fix a mechaical issue either...

[EagleMark]

Do you have a data log from TunerPro? If so post it up...

[gregs78cam]

This is sounding like a fuel supply issue. Almost like you enough for idle and maybe cruise, but when you ask for more, it's not there. That could be cuased by what you mentioned earlier about air in the fuel line. A couple of things that could cause this....1)If the return into the tank is aerating the fuel right around the pickup, the pump will pick it up and it may make proper pressure but it won't run right, the pump won't sound right either, it will be noisier. 2) I have first hand experience with this, If your EFI filter is not oriented to pass trapped air though it, it will cause big issues. Make sure the inlet is down and outlet is up.

[EagleMark]

He's changed from a inline pump from an old carb tank to a newer EFI in-tank pump now. Still same issue?

The EFI filters I use have an arrow, your saying backwards causes issues?

[RobertISaar]

if you run an EFI filter backwards, the filtering element can actually collapse and cause almost total fuel starvation.

[gregs78cam]

He's changed from a inline pump from an old carb tank to a newer EFI in-tank pump now. Still same issue?

The EFI filters I use have an arrow, your saying backwards causes issues?

The inline pump could have been sucking air from the inlet side somewhere....I've seen water pumps do that, It wouldn't leak out, but would pull air in through the seal, and act like a blown head gasket.....OR could have been picking up aerated fuel also, The intank pump like I said could be aerating the returned fuel. It all depends on the location of return and pickup.

With the filter, if it is oriented so that the inlet is on the top and outlet on the bottom it may never actually purge all the air out of it. Just some things to check.

[Mastiff]

Computer is trying to compensate for something?


I just mean this thing is in closed loop. It will compensate for fuel pressure, air leaks and other stuff within a pretty wide range to satisfy the O2. The plugs will only be rich or lean if the computer has hit the stops in its ability to make things right. At that point I'd expect an error flag.

[Mastiff]

This is sounding like a fuel supply issue. Almost like you enough for idle and maybe cruise, but when you ask for more, it's not there. That could be cuased by what you mentioned earlier about air in the fuel line. A couple of things that could cause this....1)If the return into the tank is aerating the fuel right around the pickup, the pump will pick it up and it may make proper pressure but it won't run right, the pump won't sound right either, it will be noisier. 2) I have first hand experience with this, If your EFI filter is not oriented to pass trapped air though it, it will cause big issues. Make sure the inlet is down and outlet is up.

This is VERY interesting. I was seeing air bubbles in my old setup and I could hear hissing if I put my ear to the lines. I blamed it on the in-line pump sucking air in somewhere, but I never found anything. Two things: the return line has not changed, AND my fuel filter is horizontal. It could be full of air. I take it that the factory arrangement is just the opposite, up and down. I'm going to go after this next. Kind of a bummer because I have the thing mounted so nicely in the exact same mount I had my pump in. Oh well.

[RobertISaar]

on all W-bodies, the filter is horizontal.... we never have those kinds of issues.

[gregs78cam]

Horizontal should be fine, And you do have a stock in-tank pump with the sock on the pickup right? That should stop it from picking up aerated fuel, possibly unless the return is pointed right at the pick up.

[Mastiff]

Horizontal should be fine, And you do have a stock in-tank pump with the sock on the pickup right? That should stop it from picking up aerated fuel, possibly unless the return is pointed right at the pick up.

Hmm, well that dashes my hopes on that one... I have the factory style EFI sender with the sock. It does look like the return line points right at the pickup...

http://info.rockauto.com/getimage/getimage.php?imageurl=http%3A%2F%2Finfo.rockauto.c om%2FRB%2F692-033-007.jpg&imagekey=971967-0&width=450

[EagleMark]

They work fine like that and factory truck filters are also horizontal. Is yours pointing the right way?

[Mastiff]

They work fine like that and factory truck filters are also horizontal. Is yours pointing the right way?

99% sure, but I'll double check.

[PJG1173]

just throwing this out there, but have you logged battery volts? a cold alternator will put out more voltage than a hot one. also as wires get hot they increase in resistance. is your battery, chassis, engine grounds good? I know the injector offset vs battery should compensate for this but if they are off or there is ther things factoring in... It could just be a bad ground between the block and the rest of the vehicle. my buddy had dim headlights for the longest time and coundn't figure out why, when the alt checked good and the volt meter in the dash read 14v while running. come to find out the ground strap between his body and block was bad.

[Mastiff]

Well, I think the plugs look okay, not fried or oily:

https://lh3.googleusercontent.com/-PqJfJNEW-mY/T1GZb2IyrXI/AAAAAAAACgk/gRmoHK7oJNk/s800/2012-03-02_21-08-42_817.jpg

Changing plugs around the headers is a PITA. I also looked over the fuel lines and everything looks good. The fuel filter is oriented correctly. Fuel goes into the TBI on the driver's side, right?How do you get hose for a fuel pressure gauge out from under the hood? I don't have a big enough gap, unless I rig up the little tube like for a mechanical oil pressure gauge?

:mad1:

[EagleMark]

They look preety good! Little old and rusty... thought you lived in Tuscon? Where'd the rust come from? Did you look at O2 sensor? From looks of plugs inside of O2 should look OK. Outside not crusty, dirty, oily, covered in mud?

My Blazer and Suburban I drilled a hole in firewall for fuel line to come up through vents under windshield wipers. Other cars had rubber seal and I laid the hose there and only closed the hood to first latch.

You got a data log?

[dave w]

You got a data log?

I second that request!

dave w

[Mastiff]

I second that request!

dave w

I have to remember how to do it. Just hit record in tunerPro, right? I'll get one for you guys today if I can get free.

I'm in Tucson now, but I was in Iowa for 14 years. I seldom drove the K5 in the winter after I painted it, but just being there at all... And those plugs are ancient.

I'm close to pulling the trigger on an EBL. Not just because of this, but I've been looking at them for a while and I know it's just a matter of time. I don't expect it to fix this, but I think the instrumentation will be better and easier, and Bob would tell me with total certainty what was going on if I had software questions. Plus I could stick the ECM up under the dash someplace instead of sliding around on the floor with the Ostrich hanging off. I think I could use an analog channel on the EBL to get fuel pressure out too.

Have any of you guys ever seen an ECM go bad in a way that it degraded instead of just failing? This is a long shot, but I was thinking that if the clock in the ECM went bad, it would get the injector times all wrong.

[dave w]

I have to remember how to do it. Just hit record in tunerPro, right? I'll get one for you guys today if I can get free.

I'm in Tucson now, but I was in Iowa for 14 years. I seldom drove the K5 in the winter after I painted it, but just being there at all... And those plugs are ancient.

I'm close to pulling the trigger on an EBL. Not just because of this, but I've been looking at them for a while and I know it's just a matter of time. I don't expect it to fix this, but I think the instrumentation will be better and easier, and Bob would tell me with total certainty what was going on if I had software questions. Plus I could stick the ECM up under the dash someplace instead of sliding around on the floor with the Ostrich hanging off. I think I could use an analog channel on the EBL to get fuel pressure out too.

Have any of you guys ever seen an ECM go bad in a way that it degraded instead of just failing? This is a long shot, but I was thinking that if the clock in the ECM went bad, it would get the injector times all wrong.

I've never had an ECM experience a degrading failure like you describe. My experience has been the ECM works fine or has a complete failure (no start).

I'm usually one that favors the newer 16197427 TBI PCM upgrade vs. EBL, mostly because of the lower costs involved in the 16197427 upgrade. I usually install the new 16197427 PCM back into the original ECM location and place the Ostrich 2 in the glove box. Having the Ostrich 2 in the glove box makes for an easy (unplug / plug) vehicle anti-theft system! The Ostrich 2 has a battery, so the computer does not have to re-learn if / when the Ostrich 2 is ever unplugged.

The TunerPro V5 logging options are in the Acquisition tool bar. You need to load a data stream file, .adx similar / almost like loading a .xdf. The actual data log is saved as an .xdl file, which is the file I hope you can post here for us to look at.

dave w

[gregs78cam]

I'm usually one that favors the newer 16197427 TBI PCM upgrade vs. EBL, mostly because of the lower costs involved in the 16197427 upgrade. The TunerPro V5 logging options are in the Acquisition tool bar. You need to load a data stream file, .adx similar / almost like loading a .xdf. The actual data log is saved as an .xdl file, which is the file I hope you can post here for us to look at.

dave w


I second that........look at this upgrade, it costs far less and has lots of benefits.

[RobertISaar]

i've seen partial and intermittent failures with specific ECMs. some of which were temporarily revived by smacking the box when it was driving down the road, and all of a sudden everything works perfect for a while.

and if the clock was bad, you won't get any ALDL data, i would think.

[Mastiff]

Agreed, if the clock was dead the whole thing would go. If the clock was running slow or intermittently things could get interesting though. I think if it was slow it would probably overfuel though, so mine would have to be running fast. Unlikely. I'm grasping because I can't imagine what could be wrong with my fuel system at this point.

The nice thing about EBL is that it plugs into my existing harness and has a great interface, plus actual support. I looked into it a little and logging fuel pressure is a piece of cake (once you spring $100 for the transducer :rolleye:). Plus the benefit of having it all in a single, self contained package.

[EagleMark]

EBL is a fine product but a little overkill for a stock motor, as far as support again excellent but your getting excellent support here too! It can't fix stuff that ain't right mechanically. You already have all equiptment needed to tune so if you repinned to 16197427 your still ready to go.

Once you have TunerPro RT running you'll never look back! Then you have to pay the $30 to support his efforts in giving us software that is incredible compared to anything else! Plus it data logs, tunes your bin and burns from same program! I'll upload the XDF (bin tuner) and ADX (data logger) for you.

Get it and install it then plug your cable and see which COM port it is on. Open TP and go to Tools, Preferences and Data Acqusition and choose plug in, configuration and make sure it see's that Com Port or change it, or move USB cable to another slot. Once that is done it's just a matter of Connect and when you see data Record. When your done click stop and it will prompt you to save with a name.

[Mastiff]

I do have TunerproRT going, I've just only been looking at the tables, not long term logs. I'll try to get a log today. Wife and kid stuff ya know. I'm not real impressed with the dashboard I have for tunerPro right now, maybe I'll give yours a shot to see what's in there.

Yes, you guys are helping!

I'm still liking the EBL though. Displaying and logging the fuel pressure real time would be excellent. And let's be honest, it would just be a fun toy. :cool: That's what this is all about. My K5 is no longer daily transportation.

[gregs78cam]

I think if you repinned to a '7427, and had a well layed out dash, you would be impressed with the amount of data available.

[EagleMark]

He'll be impressed with all the dash boards in this ADX. But if he had a 16197427 there would not be enough dashboard for all the data!

You can make your own dash boards too! Then right click on any and choose what you want there!

[Mastiff]

Very nice XDF. I like how everything is sorted and there are explanations with some of the items. I also see there is injector duty cycle in the dash. Anyone know where that comes from? It just pulled whatever I had in memory and it say 647%. Hmm...

[Mastiff]

Okay, here's a log file. None of this makes any sense to me. This is the stock ARJT except with VSS and EGR disabled and the BPW changed from 135 to 150. No other changes. The BLMs are a little high, but nowhere near as high as when I had the BPW up to 200 before. How can that be? The drive was typical for me recently, it did okay except for terrible hesitation on acceleration and I got a backfire on two different occasions when I tried to accelerate hard (once with normal acceleration pulling uphill and once under hard acceleration on flat ground).

What's the right way to adjust the idle air setup? Right now the throttle blades are nearly closed at idle and I can hear whistling. I thought TPS was showing 11%, but this new ADX doesn't seem to agree with that. My BLMs tend to grow at idle, I wonder if it's because the fuel is landing on the throttle and dripping in instead of atomizing into the air stream. Just a thought, but I would like advice on how best to set up the IAC and TPS. Thanks.

[EagleMark]

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?581-Initial-Setup-of-TBI-TPI-and-MPFI-systems.-Min-Air-Adjust-TPS-set-and-Fuel-Pressure

150 is just a safe range before having to calculate injector bias issues...

[dave w]

I'm still liking the EBL though. Displaying and logging the fuel pressure real time would be excellent. And let's be honest, it would just be a fun toy. :cool: That's what this is all about. My K5 is no longer daily transportation.

Some people like to show what they can build, other people like to show BLING. I'm likely to show what I've built so as to outshine the BLING I bought!:thumbsup:

dave w

[EagleMark]

Very nice XDF. I like how everything is sorted and there are explanations with some of the items. I also see there is injector duty cycle in the dash. Anyone know where that comes from? It just pulled whatever I had in memory and it say 647%. Hmm...Injector duty cycle will not work until you do the BPW **Read Me Hac** in the XDF file!

The TPS calculated from voltage is close. If you do the TPS % **Read Me Hac** it will be exactly what ECM sees.

I have been combining XDF files for years and adding and commenting. Those 2 files also do data tracing so you can see where in bin file your fueling or spark is from data. I have easily over 100 hours in those 2 files!

Your Min Air could be an issue, when TBI units wear out the throttle blades close and all air comes through IAC, blades can actually stick and you need to push hard on accelerater to snap them open when under vacuum. By the looks of your IAC count while warming up I'd say this needs to be done.

Your truck is always in Drive so I'm guessing no Par/Neutral switch? Which is OK but won't help the bump into gear...

Your VSS is not working or you don't have one which do make these run better.

Your O2 sensor seems to be working properly but you are lean everywhere except 128 WOT which is where it should be but without have proper fueling in rest of VE table would still be lean if you checked with a Wide Band O2 sensor.

You have no error codes, but did get an erro of low battry when you shut truck off at end of log, charging system is good but I would load test battery.

Now if you promise to pay for TunerPro within the month of your budget I will tell you what's wrong with your truck? :laugh:

[dave w]

I've briefly looked at the data log attached above. The overall average BLM is 140 which is lean. The overall average INT is 129, which tells me the computer is just barely able to compensate for the lean BLM's. The overall O2 voltage average is 0.315 volts, which seems low. There is an excessive amount of O2 sensor voltages in the data log that are below 0.100 volts!!!!!!!!!!!!!!! I'm guessing the O2 sensor is a single wire in the exhaust manifold? I very seldom tune a stock engine, so I'm more familiar with heated O2 sensor voltages. Typically a correctly tuned VE table will have heated 3 wire O2 sensor average voltages of 0.600 ~ 0.800 volts. Maybe it would be good plan to include an upgrade to a 3 wire heated O2 sensor with the EBL / 16197427? I can't say with 100% certainty (I'm at least 70% certain) that the O2 sensor is bad, but the data log clearly indicates the O2 sensor could be a problem.

dave w

[dave w]

I have attached the Excel spreadsheet for the .xdl file attached above.

dave w

[EagleMark]

That's normal with the cross counts on this 1227747 ECM to go below .100

The overall average is correct though because of it running so lean.

Did you see the issue yet?

[Mastiff]

Thanks for the help. I have no VSS and I have no Park/Neutral. I do have a 3-wire O2 sensor. Can you explain how it could be bad if the system is able to run in closed loop?

Can you explain more specifically what you think needs to be done regarding TPS/IAC? My TPS is exactly at the desired voltage at idle, so that seems okay. I tried tuning the idle according to the procedure, but after I set the idle so low (450-500) with the IAC unplugged, it also ran low and unhappy with it connected. I mentioned in the other thread that when I did the pin A/B trick the IAC motor would not stop making noise. I expected it to park and shut up.

What do you expect to see in IAC? I see it starting around 100 when fast idling during warm up, then going down to about 20 when it went to closed loop. Should it go lower?

[EagleMark]

Now if you promise to pay for TunerPro within the month of your budget I will tell you what's wrong with your truck? :laugh:Promise?

If your down to 20 IAC counts at warmed up idle your fine if TPS voltage is still close.

But your major issue is Knock Counts! they never stop! Even under deceleration they are going nuts. Play your log back and open the history tables and look at Knock Accumulater. You either have a noisy motor or something rattling or a bad knock sensor/ESC... assuming your timing is set correctly. With that many knock counts I'd think you'd be able to hear knock and ping!

Go into your bin and find "KNK - Min CTS to Enable" and max out tempreture and burn a new chip. Then do a data log and see how it runs.

[Mastiff]

Yeah, I have no knock sensor. The line is just hanging. Sorry I forgot to tell you that. I already have the knock disabled. :mad1:

[EagleMark]

Well did you disable it or just turn off the error code? Something is wrong because your showing knock counts like crazy! I'll try and do a data trace and see if it's pulling timing...

[EagleMark]

Looks like it's constanly knocking to me? I just played back a log on a jeep I tuned with no knock sensor and disabled and it had no knock counts?

[Mastiff]

Looks like it's constanly knocking to me? I just played back a log on a jeep I tuned with no knock sensor and disabled and it had no knock counts?

If it means something I'd love to know. I did exactly what you said, set "min cts to enable" to its max value. I also disabled error codes.

For what it's worth, I'm attaching another log from a quick drive. Difference here is BPW up to 160, idle set to 650 and the changes made to get duty cycle and TPS into the data stream. I can't see any duty cyle values over about 25%.

Thanks.

[dave w]

I ground (battery -) the neutral / park wire (usually pin B10?), which always sets the ECM to park / neutral.

dave w

[Mastiff]

I ground (battery -) the neutral / park wire (usually pin B10?), which always sets the ECM to park / neutral.

dave w

Does that change something?

[dave w]

I've briefly looked at the data log attached above. The overall average BLM is 140 which is lean. The overall average INT is 129, which tells me the computer is just barely able to compensate for the lean BLM's. The overall O2 voltage average is 0.315 volts, which seems low.
dave w

The log did not show an improvement in overall BLM average, actually went up from 140 to 144 (weird!). A BPW from 150 to 160 should have lowered the BLM average from 140 to about ~133 or so. Strange as it seems, the INT overall average went from 129 to 128. The INT's seemed to respond as expected with an increase in BPW. The overall O2 voltage increased to 0.402 volts, which responded as expected. The spreadsheet does not show any O2 cross counts. The spreadsheet shows a max Knock Count of 123.


dave w

[dave w]

Does that change something?

Heck yes! It tells the ECM not to look for a VSS, which keeps WEIRD things from happening!

dave w

[EagleMark]

If it means something I'd love to know. I did exactly what you said, set "min cts to enable" to its max value. I also disabled error codes.

For what it's worth, I'm attaching another log from a quick drive. Difference here is BPW up to 160, idle set to 650 and the changes made to get duty cycle and TPS into the data stream. I can't see any duty cyle values over about 25%.

Thanks.I just added the Injector Duty cycle and didn't fully test it so disregard that. But if you did type in the letters correctly something is not right because MPG history table isn't working, which it did for me so you may have typed in the hex letters wrong too?



The log did not show an improvement in overall BLM average, actually went up from 140 to 144 (weird!). A BPW from 150 to 160 should have lowered the BLM average from 140 to about ~133 or so. Strange as it seems, the INT overall average went from 129 to 128. The INT's seemed to respond as expected with an increase in BPW. The overall O2 voltage increased to 0.402 volts, which responded as expected. The spreadsheet does not show any O2 cross counts. The spreadsheet shows a max Knock Count of 123.


dave wI think he applied the AFR **Read Me Hac** which I updated to **Read Me Hac IN PROGRESS** so that is probably why he lost cross counts.

His knock counts went way down? But not off? It makes no sense he raised BPW and BLM got leaner, so it's either the absense of VSS or he's loosing fuel pressure while under load?

Looking at your first spead sheet does show a lot of 0 and 1 and 4 in O2 voltage. I am used to seeing them under 100 but not that low! So your diagnoses of O2 sensor issue could be valid? I just don't see them that low in TunerPro while watching the Data? And on the spread sheet they seem to go to 1, 4, 0 for awhile then back to 3 digit numbers crossing correctly.

[Mastiff]

Without VSS I don't think you could do MPG, right? Without that you can't know how far you went.

I'm skeptical of just looking at the average BLM. The first log I sent started from scratch, so all the BLMs were 128 to begin with. During the first drive they went up to 150 or more in many places. When I changed the BPW and reran, the old BLM values were still in memory, so they would get called up and show up in the stream, even if they were in the process of going down. You would be averaging those in. Maybe I should make a habit of clearing the memory after every bin change for better apples to apples comparisons.


Heck yes! It tells the ECM not to look for a VSS, which keeps WEIRD things from happening!

Interesting. When I researched it people claimed it didn't matter, but maybe they assumed there was a VSS.
I did apply all the hac things in there, so whatever that does is happening.

EDIT: An old thread I found on park/neutral: http://www.thirdgen.org/techboard/diy-prom/316146-park-neutral.html

[EagleMark]

Your right, no VSS = no MPH = no MPG.

The VSS in thread was tuned for drive and he made adjustmants to idle to compensate. I've always grounded the wire becuase in park it would not look for VSS. On the other hand 1227747 has no P/N switch on manual (still has VSS) but there's no need for IAC Idle control like an auto in drive. That said I had a conversion for awhile, like over a year and installed a VSS and it ran much better?

I still think your fuel pressure is to low... dave found some issue with your O2 readings I did not see while watching in TP but they showed in spreadsheet?

[dave w]

Interesting. When I researched it people claimed it didn't matter, but maybe they assumed there was a VSS.
I did apply all the hac things in there, so whatever that does is happening.

EDIT: An old thread I found on park/neutral: http://www.thirdgen.org/techboard/diy-prom/316146-park-neutral.html

I've always grounded the ECM Park / Neutral input when NOT operating with a VSS. The Painless TBI Wiring Manual has the Park / Neutral input grounded:

http://www.painlesswiring.com/Manuals/60101.pdf

VEHICLE SPEED SENSOR AND TRANSMISSION LOCKUP FUNCTION
Before you install the harness, please decide the following things:
a. Are you going to use a 700 R4 Lockup Transmission that you want the computer to control the lockup on?
b. Does the engine have to be emissions legal; i.e. does the EGR valve and /or air solenoid, and diverter valve need to be connected?
If you answered yes to either or both of these questions then you must connect the
wires labeled VSS to a vehicle speed sensor that will provide a two (2) pulse signal to the computer. The Throttle Body the sensor should output a square wave. Painless Wiring offers the correct speed sensor for use with cable drive (mechanical) transmission outputs, p/n 60115
If you answered no to both of these questions then you may choose not to use a vehicle speed sensor, but the vehicle will operate more efficiently with one.

dave w

[Mastiff]

You think the VSS could be causing all my problems? Maybe the acceleration problems?

I don't know what to think about the fuel pressure thing. I have high BLM across the board, including at idle where I'm showing normal fuel pressure. So it doesn't seem like fuel pressure can explain everything. Maybe it's dropping under load and making things worse there. I'll need to get fuel pressure into the cab to see that.

How do O2 sensors go bad? If it was shot, closed loop would not work and it would throw a code. Can it go partially bad? Maybe the heater stopped working. I forgot if they read rich or lean when cold... I'm going to go back and read the test procedure you linked.

[Mastiff]

Can you link the O2 sensor thread you were talking about? I can't find it. Since the vehicle runs without codes and passes emissions, I think the O2 is probably good, but maybe the heater isn't working. How hot should it get if I just power it up on a bench? It's hard to test on the truck because it gets power from the same source as fuel pump, which only runs when the engine is running.

The sensor itself is grounded through the headers? I wonder if this is ever and issue.

[EagleMark]

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?82-Good-read-on-O2-sensors

I had to do some testing on my 1227747 Suburban today mainly to check Injector duty cycle. It is off so disregard the reading. The BPW is correct.

BPW is also correct on yours.

I also tested the knock disable by raising temp and still got some knock counts, you disabled it and got WAY less knock counts...

I took your data and may data and made spreadsheets to compare. Only difference is my truck is stock5.7L Suburban with VSS and P/N switch.

I never raise BPW much because I read long ago if you do there are other changes that have to be made. I think it's injector bias? When ever I need more fuel I raise pressure. Sure enough I raised my BPW to 180 and went PIG rich at idle but the surprise came at higher RPM I went lean to 138 in spots!

Back to 135 BPW and I was 127 to 130 across the board!

I made a exel spreadsheet of my log and your log so I have actual numbers to compare.

I think you have 2 problems.
1. First is fuel pressure. You are close at idle to 128 but as TPS % rises so do your INT and BLM so your short on fuel. This is consistent throughout your log. Mine does not.
2. Your O2 voltage goes to 4 in many places and stays there! Even during BLM learn enabled, then goes back to normal. So I think you have an O2 sensor problem as well. If BLM Learn is enabled and it's taking a reading of 4 for many cells in a row the learn is going to be WAY off! Mine goes under 100 to as low as 80 sometimes during cross counts for one cell but jumps right back up and never goes as low as 4. Mine will only go as low as 38 during PE and HiWay lean cruise which are both open loop, you can also see BLM learn Enabled turns off as well.

HTH! :rockon:

[RobertISaar]

assuming it's like the P4 units, knock counts will still be reported any time the knock sensor detects it, false or not. it's just that under the temp thresholds, it won't apply any KR.

[Mastiff]

I have a spare O2 sensor and I tried testing it. The propane torch test worked prefectly. Got 0.9 volts and it dropped off quickly. Next I tried applying 12V to the heater. The voltage went up to 0.07 volts or so and wouldn't go above that. I wonder if that's normal. Is the heater just sort of a helper, not really able to get it to temp by itself? With headers I wonder if I could still be having trouble with a cold sensor.

[EagleMark]

I've never measured voltage on heater circut so don't know? But if the sensor side tested good give it a shot. It's just to help element warm up inside, outside of my wideband only gets to 120 degrees?

[Mastiff]

The old O2 sensor seemed okay, but a little corroded around the o-ring. I swapped in the new one just for the heck of it, but it didn't make any difference. It seems like it has to be fuel pressure somehow. The test I did was to check the voltage at the pump connector while the truck was running. 13.8 volts. So, I've got about 1 volt drop in the wiring back there. Anyone know how much current the pump wants? I attached a battery charger and it couldn't make pressure in its 2 amp mode (didn't verify the 2 amps). In 10 amp mode it made 10 psi with engine off, 50 amps also made 10, so that's what the regulator wanted.

Maybe I need to rewire the pump circuit with heavier gauge wire.

[EagleMark]

A battery charger is a bad test. But if you have 13.8 volts back there it should be fine...14.8 at battery is a little high, 14.2 is optimal while running. On masks that have battery voltage and fuel pump voltage I have noticed less then 1 volt difference at pump. Now if you had a battrey back there, wired to fuel pump with a charger on the battrey and got 13.8 to 14.2 + volts and fuel pressure went to 13 then I would say yes.

You may need bigger wire? I don't know what's required, I usually go overboard there on conversions because of the long distance.

But 10 PSI is not enough... or 11 or whatever your gauge is reading could be a little off. Logs show more TPS/load and BLM numbers go lean. You tried to compensate for it by adding BPW which didn't work, and my test on perfect BLMs went rich idle and lean higher RPM. So I'm gueeing when you were at 135 BPW you were lean at idle too?

Your gauge is showing to low a pressure. Your logs are showing to low a pressure. You need more pressure! Maybe the regulater was never right and you put a new diaphram and spring in and nothing changed... maybe it is your wiring to pump or just need an adjustable regulater, or both?

I also tried the combining VE1 and VE2 today. I had several bins ready to go for a drive and with the emulater it was easy to log each. When adding VE1 and VE2 there are spots that add up to over 100 and VE table 1 cut them back to 99.61? IIRC... I tried with 25 in 0 RPM colomn and 0 in 0RPM column in VE2 and both logs were same as VE1 and VE2 as is. So GM made a mistake there as it has been mentioned. But with that a 1227747 would need more BPW or more pressure to compensate for a stock tune to get within tuning guidlines of no higher then 95 VE. I also noted that these cells that add up to over 100 can't be reached without going into PE which adds the extra fuel it needs and why it gets away with being wrong!

[Mastiff]

Okay. More weirdness. I pulled the regulator off and adjusted it almost all the way up. Maximum pressure on the spring from the little inverted cup thingy. Fired it up and no difference in fuel pressure at idle! I took it for a drive though and the BLMs are very good. Now I question if my pressure gauge is faulty. Or (long shot) there is back pressure from the return line that kept it to 10 before even though the the regulator wasn't doing anything, now the regulator is only at 10, but keeps it while under load. The regulator looks so simple, how can it be bad with new spring and diaphragm? What else is there?

Anyway, here's the setup. Cop car injectors, stock ARJT except for 175 BPC, and now all BLMs are between 120 and 134. Go figure. :mad1:

If normal BPC is 135 and I'm at 175, and cop car injectors are 65 instead of 55, that's about 35% extra fuel over stock, total. But if I'm at 10 PSI instead of 12, that's 20% less, so maybe I'm in the ballpark accounting for the headers and whatever else.

[dave w]

I'm figuring something had to change to cause the BLM's to improve ... so it seems likely the changes to the pressure regulator is helping the BLM's. Maybe I forgot, or maybe it has not been mentioned, was the pressure regulator spring replaced?

dave w

[Mastiff]

Yes, the spring was replaced, then I cranked it up. One weird thing is that the replacement spring was much shorter than the old one. Anyone know if these regulators changed design over the years? I bought a kit for a 1991 Blazer. I have no idea the source of my TBI.

[EagleMark]

I've never seen or heard of differant regulaters? I did notice once a spring with adjustable regulater was shorter but stiffer? Did you do something to wire at fuel pump when you were testing? Since you had rust on plugs, is there rust on frame where the pump is grounded? You are loosing one volt back there from battery voltage you said?

Remember what happened in my test today with high BPW of 180? BLM were perfect at 135 BPW, went to 180 BPW and idle went 108 Max low but high rpm went leaner 13x?

Still does not seem right you got no pressure increase when adjusting regulater all the way up. Stock spring should go to 15 PSI. You got 15 PSI from gauge when you pinched line for short time earlier. Unless gauge has gone bad? If you have blockage on return line pressure goes up! You could use a pair of needle nose vise grip and adjust so they partially block return line and watch gauge to get up to 14-15 with BPW at 135 and re log.

[PJG1173]

how old is the pump? sounds like its stalling at 10 psi where it should be stalling around 15.

[Mastiff]

Pump is new. I did the pinch test and went to 15+. I can redo to confirm. I'm blaming the FPR right now. Maybe someone butchered the housing in order to use an external regulator at some point. I don't know the history on this thing.

Let me try my theory on you guys again: Previously, the regulator was totally shot and I got 10 PSI at idle because of resistance in the return lines. When the injectors went into use before, less fuel needed to flow to the return, so the pressure dropped and I got all my weird symptoms. Now, the regulator is actually set for 10 PSI, so shows no difference at idle, but maintains 10 under load so stuff makes more sense. This theory does not explain why I'm only getting 10 with the spring maxed out. Maybe I can find another TBI or pod on Ebay for not too much.

FYI, this thread claims you can just force the bottom of the FPR with pliers to make it adjustable: http://www.ihonlynorth.com/forums/fuel-injection/4273-faq-injector-removal-regulator-adjustments.html

[PJG1173]

I ran into something similar with mine. when I first started messing with it I had 9psi stock. I made the regulator adjustable and had to crank it almost all the way up just to get 11.5. I figured the pump was weak so I put a pump out of at 01 vortec truck in it. still had 11.5 psi after I put a pump that could handle 55+ psi. I changed the diaphram and left the adjustment where I had it and broke the needle on the guage and flooded the engine first time I started it. when I took it back appart to adjust the regulator I took the diaphram back out and compared the two. I noticed on the old diaphram there was scoring on the part that blocks off the fuel passage. I would assume if you could get enough scoring on the diaphram to reduce fuel pressure that the same would be applicable to the housing its mounted to.

reading that thread you posted kind of has me wondering. that is the first I have heard of doing it that way. I don't remember mine being loose enough to do that with. I have a spare regulator in the garage I might have to see if that works on. not holding my breath though.

[EagleMark]

FYI, this thread claims you can just force the bottom of the FPR with pliers to make it adjustable: http://www.ihonlynorth.com/forums/fuel-injection/4273-faq-injector-removal-regulator-adjustments.html
But after you force/brake it loose what keeps it from vibrating loose and moving?

It may be that shorter spring you got in the rebuild kit is no good? Was your old spring OK? Put it back now that your regulater is adjustable and working and return line fixed.

[PJG1173]

But after you force/brake it loose what keeps it from vibrating loose and moving?

that's what I was thinking, but i thought that about drilling out the weld holding the adjustment screw on the bell too.

[dave w]

I use an EFI portable fuel cell to verify fuel pump / pressure regulators. Maybe you can do something similar? The EFI fuel cell is handy to have when I run an EFI engine on a stand.

http://i239.photobucket.com/albums/ff290/buildabot2002/454 MPFI/DSCN2192.jpg
(http://<a href="http://s239.photobucket.com/albums/ff290/buildabot2002/454 MPFI/?action=view&amp;current=DSCN2192.jpg" target="_blank"><img src="http://i239.photobucket.com/albums/ff290/buildabot2002/454 MPFI/DSCN2192.jpg" border="0" alt="Photobucket"></a>)

dave w

[Mastiff]

that's what I was thinking, but i thought that about drilling out the weld holding the adjustment screw on the bell too.

I tried my trick with bending the tab, rotating and then bending the tab back. Of course the tab broke off immediately. I ended up putting loctite on the threads and setting it where I wanted. Should hold, but may be a pain if I need to adjust again. With the tab gone, you could use a lockwasher to hold it. I just didn't have one the right size on hand.

[PJG1173]

I think the spring keeps enough tension on it to keep it from moving. some regulators don't have a tab sticking out or a slot for the tab.

[Mastiff]

How can I tell if I have 350 or 454 throttle body and/or pod?

[PJG1173]

the 454 tb has 2" bores vs the 350 with i think 1 11/16 bores. I don't think there is a difference in the pods. I know some of the late 454's ran 30 psi but that was the regulator controlling that.

[Mastiff]

I'll measure when I get home. Here's a pic of my setup:

https://lh4.googleusercontent.com/-haL0HcBHFFo/TjtciSsvJ_I/AAAAAAAAAjA/Sxqr57VIOjY/FigE8A-New_throttle_body1.jpg

[dave w]

The 454 Throttle Body has a flat 4 pin IAC connector. The 350 Throttle Body has a square 4 pin IAC connector. The pictured Throttle Body is NOT a 454 Throttle Body.

dave w

[Mastiff]

Thanks. Must be an illusion. The bores look bigger than this one:

http://www.ebay.com/itm/340hp-46mm-GM-TBI-kit-w-injectors-AFPR-spacer-1986-95-/230439378150?pt=Motors_Car_Truck_Parts_Accessories&hash=item35a741dce6&vxp=mtr#ht_1567wt_1289

I (http://www.ebay.com/itm/340hp-46mm-GM-TBI-kit-w-injectors-AFPR-spacer-1986-95-/230439378150?pt=Motors_Car_Truck_Parts_Accessories&hash=item35a741dce6&vxp=mtr#ht_1567wt_1289)'ll be curious to measure when I get home.

[EagleMark]

Well I see a few potential issues. You should have spark pilu wire seperated as much as possible not tied together. You should also not tie any part of the EFI harness to spark plug wires. You are running a large cap HEI distributor and it has differant latency values then the bin you are using that came with small cal EFI distributor. All these are known causes of issues.

But still not your fuel pressure issue...

The BB and SB tbi pods are all the same except one that had a differant stud for mounting, I think it came on Caprice which uses 2 extended TBI mounting bolts for air cleaner hold down, some other thread Six Shooter had pictures of 2 studs, one is bigger, I looked in my TBI rebuild kit and it does come with 2 injector pod gaskets and differant size holes for stud. The 1994-95 7.4L TBI runs a 4.3L size injector at higher pressure so it must have a differant spring but I've never had one so I don't know what they do on those years.

Does your spray pattern look good? No dribbles?

[EagleMark]

I've mix matched a lot of parts and have a 4.3L 5.7L and 7.4L TBI units here and all injector pods look identical. Only difference is bore size and injector size. Dave is right about the IAC differant on BB TBI but I think some early ones still had regular IAC... the BB also has 2 wires changed in wiring diagram.

Still don't think this is your issue...

[Mastiff]

Somehow my pressure is not coming up as easily as it should. I'm pretty sure when I pinch the return line tonight I'll see the pressure go way up. So why isn't the regulator doing it? That's the big question. I don't know what I could replace or fix to solve this. Maybe I'll pull the FPR again and see if there is any strange scoring where the FPR button mates against the fuel inlet...

[dave w]

The 454 IAC is bolted to the Throttle Body.
http://www.ebay.com/itm/New-GM-TBI-IAC-motor-1987-95-BBC-7-4L-454-/190593448135?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c604138c7&vxp=mtr

dave w

[EagleMark]

Somehow my pressure is not coming up as easily as it should. I'm pretty sure when I pinch the return line tonight I'll see the pressure go way up. So why isn't the regulator doing it? That's the big question. I don't know what I could replace or fix to solve this. Maybe I'll pull the FPR again and see if there is any strange scoring where the FPR button mates against the fuel inlet...Or the short spring you put in?

[Mastiff]

Well, I fired it up just now and pressure read 13-14 PSI. Must be that the gauge is having trouble hot and it didn't read right last night. I went ahead and ordered EBL and a powered fuel pressure transducer, so when I get that hooked in I'll know for sure what's up with the fuel pressure. I'll play with the tuning in the mean time to see what I can do. 175 BLM with cop car injectors seems like a lot of fuel, so that's still a mystery. My throttle body has wide openings at the top, but they neck down where the butterflies are. GM must have had different designs for different applications.

So what do I need to change to account for my distributor style?

[Mastiff]

Got the EBL yesterday. Haven't fired it up yet, but reading through the documents, this thing is really cool. In addition to the main stuff like a great interface, better/faster logging and a bigger VE table, he's got all kinds of little cool features. There are 8 A/D inputs, one of which I'll be using to read fuel pressure, plus fan control, A/C clutch control, and an input for higher idle (like for using a winch or crawling). The auto VE adjust will be awesome instead of cutting and pasting between Excel and TunerPro. Oh, and the fact that every entry in TunerPro is documented is so helpful.

I'll report in again once I've had a chance to run it for a while.

By the way, BobR told me that VSS doesn't really do much. The main thing he thought might be important is getting into highway mode if you do much of that kind of driving. I'm starting to wish I had it though, just for logging purposes and so I can instrument out my MPG. What do you guys think is the easiest way to get VSS onto my 83 K5 with cable speedo?

[EagleMark]

Congratulations on having the coolest aftermarket product made for GM ECMs! :happy:

Here's a thread we recently had with all sorts of VSS options.
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?641-VSS-Speed-Sensors


By the way, BobR told me that VSS doesn't really do much. The main thing he thought might be important is getting into highway mode if you do much of that kind of driving."BobR told me that VSS doesn't really do much" That is a broad statement and there is probably not another person on earth that knows more about these ECM/PCMs. He could probably write a 4 page review of exactly what it did and reference every possibility scenario of RPM/MAP/MPH from memory! But I will say that when I had a 1227747 ECM TBI conversion on my Scout II for over a year and added VSS that there was a noticable difference in driving and overall performance at all speeds and idle. How much? I don't know but I liked it!

[Mastiff]

Yeah, I can't explain it. I basically just asked him flat out if it was worth my trouble to install a VSS for around town driving and he said no. Depending on the pain and expense level I might install one anyway. I'll go check the link you posted.

[EagleMark]

The expense is $75 to put one in your speedometer line, time to run wires from there to ECM.

As far as if it's worth it? Get your truck dialed in and drive for awhile then add one and see if you notice the difference I did...

[Mastiff]

Can you confirm that the VSS signal goes between open and ground? I think to install the JTR VSS I would ground one lead and wire the other one to the ECM. Is that right?

So far the EBL is awesome. Maybe my previous ECM was busted. I loaded up the EBL with a standard bin, set the BPC to 135 with my 65# injectors and all the BLM values are coming out less than 128 (like ~110ish) as would be expected when dumping extra fuel like that. The behavior of the previous ECM is a complete mystery to me.

I'm waiting on a connector to get my fuel pressure wired in to the EBL. That will tell more of the story.

[EagleMark]

Wow that's weird? And great! So you may have been fighting a bad ECM the whole time...

VSS is wired that way with VSSB only one input to ecm, but since you have an EBL and adjustments I would ask Dynamic EFI.

http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=339&d=1320981977

[Mastiff]

Got the fuel pressure wired in to the EBL just now. Showing 13 psi on the display at idle. No noticeable change just from revving. I think it should be fine, but it will be reassuring to log some data and make sure I have no drop under load.

[EagleMark]

That was really a pain! Your fuel pressure gauge was wrong and you had a ECM issue... I hate when that happens! :mad1:

Well your set with a sweet tuning set up now! :rockon:

[EagleMark]

And this is with the BPW already bumped up from 135 to 150. The BIN I'm starting with is ARJT, which I adjusted so that the VE2 table is zeroed out - just to make the tuning easier.

One thing is that the 135 BPW seems to come from a nominal fuel pressure of 12 PSI. My fuel pressure is steady at 9-10 PSI. Just working the math, this would seem to want to push the BPW up to about 180, all else equal. The only major mod to my engine is headers, but that might push the efficiency up a little. I don't mind trying the 180, but it makes me wonder how this ever worked in the factory. This has been bugging me since this started and I knew it was wrong to change BPW just to try and add fuel. I tested it and it failed. So I did a lot of reading and came to same conclusion I did long ago when starting a tuning project on a built engine.

1. First you have to know approx HP engine will acheive.

2. Then need to have injectors and pressure to meet that HP number.

3. BPW or BPC is specific for injector size-CID- Fuel Pressure.

If you have enough fuel to cover WOT high RPM of built engine then the BPW or BPC should stay the way you calculated it. Then work on idle and cruise VE.

Here's a link to calulaters used for BPW on 7747 and an entire thread for calculaters and information.
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?170-Injector-size-vs-HP-pressure-math-needed&p=2589&viewfull=1#post2589

[Mastiff]

If the VE of the bin you start with is already at 100% in some place though, you have no room to tune. As far as I know, the only option is to increase BPC.

[EagleMark]

$42 is the only bin known to have this mistake from factory. The areas that add up to over 100 are all in PE zones as well so extra fuel is added there. Increasing BPW is not the only option and it's wrong option. Raising fuel pressure or installing bigger injectors and calculating BPW is correct way.

EDIT: Robert has corrected me and there is more then $42...

[RobertISaar]

$42 isn't the only one....

in fact, one that comes to mind is $8F, which is the turbo 3.1 code. a LOT of over 100 values when combined.

[Mastiff]

I would think if the VE values are coming over 100 the BPC must have been calculated incorrectly. A factory engine sure shouldn't be able to get there. Maybe I'm misunderstanding though.

[RobertISaar]

for some reason, there are a bunch of factory calibrations that do this. whenever i see it, i jump into the algorithm to see if it gets truncated to $FF(d255), and it does in every one i've looked at.

supposedly, the early Q4 masks allowed an over 100% value but i haven't confirmed this.

[EagleMark]

Factory messed up! To many chief engineers and not enough indians... in the end you can add the 2 up to 150 but only going to get 100 output... and that is beyond the rules of tuning keeping it under 95 VE...

But in the end it passed all tests and EPA requirements. I wonder when they noticed and who got fired?

[srobertsfsj]

Now that I am back on the road and driving the Jeep again I wanted to look at addressing my hesitation issue and I ran across this thread. I have quite a bit of hesitation off the line and noticeable lag at speed and I give it gas but once it catches up it seems to have good power and I have a good tune with my BLM numbers looking good thanks to the helpful folks here. Reading through the thread I gathered some of the major things to look for are the pressure regulator, fuel pump, O2 sensor and voltage. O2 sensor is new, voltage is good and I am ruling out the fuel pump since I switched from a frame mounted pump to an in tank pump (both new) with no change. I don't have a pressure tester and money is tight so I can't buy both a tester and a rebuild kit just yet. Anything else that I should look for while I am saving up?

[FSJ Guy]

I would continue playing with fuel tuning and timing.

IMHO, tuning areas where the MAP and TPS are changing is the hardest. If you have good WOT power, chances are that it's not a fuel pressure issue.