Newbie tuning saga of my LS Jeep TJ

[jeeper]

I hope I'm in the correct place for this thread. If not moderators please inform/correct me.

I am working on a 2000 Jeep TJ that has had a 2000 Silverado 5.3 transplanted. I did everything myself so far but am not doing so well getting it to run properly.

It actually runs fine but seems to be getting more and more lean the more I drive it. It's to the point now where I'm getting nervous about driving it for fear I'll be burning a piston or something.

This thread is kind of a continuation of my introduction post here:

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?8976-Obligatory-first-post-introduction-from-a-newbie-to-EFI&p=83085#post83085

Thanks to user steveo I have been able to start focusing on fuel delivery before I try to do any tuning on this setup.

In my intro threadf (in case anyone hasn't bothered to check it out) I have determined I wasn't getting proper fuel pressure when I started revving the engine. Today I decided to disconnect the vacuum line on the rail mounted regulator and test again before I start replacing parts. I linked a video in that introduction thread.

Since then I have taken the Jeep for a test drive and recorded the wideband gauge to watch the AFR. It definitely runs rich at idle now but still goes lean on acceleration.

Here is a shaky video of that test.

https://www.youtube.com/watch?v=osLMYH3iFbM

At this point I think I need to determine if it is a vacuum leak or a faulty fuel pump causing my lean condition. Or possibly the regulator restricting fuel flow? I was suspecting a vacuum leak early on in this swap but thought I had that ruled out. Now I'm not so sure.

I'm a complete newbie to EFI but I have rebuilt a few engines in my day including a 6.2 diesel a first generation 5.7 Chevy small block and a Jeep 4.0. I'm not a complete stranger to turning wrenches but I consider myself a shade tree mechanic at best and am ready to learn EFI.

If anyone has any suggestions I'm open to any and all.

[dave w]

Can we figure the wring and flash are 100% correct?

Figuring the wiring and flash are 100% correct, are there any error codes?

Often the oxygen sensors are the cause for running rich. A flat line voltage from an oxygen sensor indicates a faulty oxygen sensor.

Have you read the exhaust manifold temperatures on each cylinder with an infra-red thermometer? A healthy engine will typically have every cylinder with about the same temperature. If the exhaust manifolds are not equal, the injector or the coil for that cylinder could be faulty.

If the fuel and spark are good, then look at the MAF frequencies. Higher RPM's = higher MAF frequencies.

EFI --- Fuel (injector) / Air (MAF) / Spark (Coil)

dave w

[jeeper]

Thanks dave w.

I believe the wiring and flash are indeed 100% correct. I do have an engine code for evap related problems. I don't have any evap parts installed on this vehicle. I haven't turned those codes off yet in my "tune". I am using EFILive to tune this because I had already purchased it to tune my Duramax truck. (I will be learning to tune that someday as well.) The EFILive package came with two vehicle licenses so I used one for this swap vehicle. This swap is using a drive by cable setup with a 512kb red blue PCM that I believe to be referred to as a P01.

I did create a custom OS I guess. I merged the manual transmission segment from one OS into another of the same. The operating systems were both 12212156. Unfortunately I don't remember what was what but I think the manual transmission originally had a 5.7 engine and the auto was a 5.3. Either way the PCM seems to like it just fine.

I have set up the EFI software to log my from the PCM and do have a wideband (an AEM 30-0334) setup to log using analog into my V2 programmer. In this case the analog input from the AEM is actually faster than serial and was recommended by the guy that wrote some custom firmware for the gauge. I'm not sure if he works for AEM but he seems to know a lot about them anyway. I will also be using that wideband on my next project that is already underway. The wideband I have will communicate directly on the OBD port of my Gen iv (E38) computer used in that project and has a pretty good resolution as I understand it.

Anyway I do see both narrow band sensors functioning properly now. I did have them wired wrong when I first started it. I had originally wired bank one on the right side and bank two on the left. With true dual exhaust there was no way the narrow bands could properly control the fuel...I have that corrected now.

When I first started driving the Jeep I was running a bit on the rich side. If I disabled closed loop it would continue running a bit on the rich side. It never runs below 14 now when I'm driving except at idle.

All the O2 sensors are new but almost everything else is used in this swap. It is a new flywheel and clutch though. My intention for this swap was to learn to tune and have some fun. When I get my next project done I will be selling this Jeep. I expect to have all the bugs worked out by then... I was trying to keep this a relatively low buck swap. So far I've succeeded.

Here is this Jeep project documented on another forum:

https://www.wranglerforum.com/threads/tihidi-yet-onother-gm-engine-swap.2385859/page-2#post-34830471

Here is a link to the Jeep I plan to keep for a long time. It is still on hold but I plan to finish it some day:

https://www.wranglerforum.com/threads/1998-tj-resto-mod-to-cj.2234433/

[dave w]

I worked on a similar tune several years ago, 5.3 / manual trans. The 5.3 was not offered with a manual. I opted to use a factory 12212156 4.8 / Manual flash VIN 1GCEK14V32Z186112, then update the 5.3 parameter "without" segment swap. I was not satisfied with the outcome of the 5.3 / Auto to Manual segment swap I initially tried. The biggest issue I experienced with the manual segment swap was drive-ability, deceleration fuel cutoff (DFCO) was horrible, even with a VSS!

The basic difference between the 4.8 and 5.3 are fuel tables, injector parameters, and spark tables.

I use TunerCats .cal files, which won't work with EFI Live.


dave w

[jeeper]

I remember reading somewhere that I should start with a manual transmission OS so I'm fairly sure that's what I did. What I don't remember is how I segment swapped it. I do have a .bin of my current tune. I'm not necessarily stuck on EFI Live as my tuning option of choice. It seems like the obvious choice right now though.

My end goal is really to have a fairly good understanding of how the modern PCM/ECUs function. I think I have a 30,000 ft view understanding, now I'm trying to zoom in and see how everything fits together. It seems so far that the volumetric efficiency table is the main table that gets used to determine how much fuel to add and other factors like intake air temperature, throttle position and manifold pressure are used to alter that amount? Then the spark advance table plays into that somewhere...

I don't have a vss installed on my vehicle yet. Everyone says it's essential but I'm not really sure I understand why. My Jeep seems pretty acceptable to me compared to my old sbc gen 1 swapped CJ7. This jeep has more power and gets around the same fuel economy as I was getting in my old CJ7. Once I get the lean condition figured out I hope to get a tune on it and expect to get a bit better economy too. I suspect I may be able to achieve 16 mpg all around.

I have double checked my engine for a vacuum leak. I did find a minor leak that I fixed yesterday but there was no noticeable change if AFR. I'm resigned to drop the tank and replace my fuel pump at this point.

For a last ditch effort I plan to try resetting my LTFT and disabling closed loop to see if I can get this engine to run rich again on this pump/line setup.

[steveo]

For a last ditch effort I plan to try resetting my LTFT and disabling closed loop to see if I can get this engine to run rich again on this pump/line setup.

oh god no

when your AFR is way out to lunch on a stock engine you don't just tune it to add more fuel. that's NOT what tuning is for. fix the problem

a stock calibration on a stock engine should not run lean under heavy throttle in fact it should run quite rich

if its truly getting leaner as you drive it that's a sign there's a fuel delivery component that's on the way out


I don't have a vss installed on my vehicle yet. Everyone says it's essential but I'm not really sure I understand why.

your ecm will behave differently whether the vehicle is moving or not moving. there may be minimum enable speeds for certain things. totally depends on your calibration/os but a VSS is good to have for sure.


It seems so far that the volumetric efficiency table is the main table that gets used to determine how much fuel to add and other factors like intake air temperature, throttle position and manifold pressure are used to alter that amount?

yep, if you're running a speed density setup (no MAF), that's pretty much how it works. a VE table is a map of how much air your engine can move at any particular point of rpm and vacuum. on a stock engine the adjustments to the VE table should be pretty minimal.


Then the spark advance table plays into that somewhere...

only in terms of more/less efficient combustion requiring slightly different amounts of fuel.

[jeeper]

Thanks again steveo.

Lol, I sure don't plan to tune around a mechanical problem. I just wanted to be sure there wasn't some parameter in the computer that was causing the lean condition.

Is it possible the GM fuel pressure regulator could be restricting fuel flow even when it has no vacuum line attached? I called my local NAPA and was quoted around $150 for an original OEM replacement so I don't want to start swapping new parts in on a whim. Edit: I just looked on Amazon and see it closer to $50 which I'm willing to spend...

I'm not opposed to replacing my stock fuel pump. It seems likely that would be the problem since it has moving parts and is probably 20 years old. What I don't really understand though is with the vacuum line disconnected the gauge clearly shows 58 pounds pressure at the rail and it doesn't seem to be dropping while I rev the engine up. This leads me to believe the pump is keeping up with the engine demand and somehow the engine isn't demanding enough fuel or the regulator isn't allowing it in to the engine? Or I guess one other possibility would be all my injectors are plugged up not allowing enough fuel in? That just seems so unlikely to me though.

[jeeper]

So last night I dropped the tank and started replacing the fuel pump. I used a new Bosch pump. It was the replacement pump for the TJ I had previously and never installed. The only specs I could find for the pump weren't actually from Bosch but this pump is supposed to be capable of over 100 psi. I haven't tested pressure yet but I'm sure it's fine.

Changing the pump wasn't without incident but I have the new pump in and the tank not leaking fuel now. It didn't help. I'm still running very lean.

So I just got back from NAPA with a new fuel regulator. I hope to get that installed this evening and see if that helps. It occurred to me this morning (after I already had everything buttoned up for a test) that possibly my fuel line from the tank to the rail has an obstruction in it? It could possibly be that the line isn't allowing enough volume of fuel through but because it isn't a complete blockage I have good pressure?

[jeeper]

I'm just about at my wits end. I just replaced the fuel pressure regulator. Still no change. Once I go off idle I see the AFR jump to 15-16 and climb to over 18 when I really rev it.

I'm not really sure what I'll do next...anyone have any suggestions?

[In-Tech]

Post your efilive and/or .bin file

[steveo]

are you sure your wideband is okay? when it goes into close loop what are your trims, and what does your wideband say?

are you sure your bin is correct for the engine?

[jeeper]

This is what is in the PCM right now.

I've checked a couple times for vacuum leak but am contemplating building a smoke machine and doing a smoke test at this point. That's all that makes sense as to why it's so lean in my brain.

I can read this tune out as a .bin if needed. The .bin I have isn't current but isn't too much different.

[jeeper]

Hey steveo I didn't see your post until I responded to the other.

At this point I'm not really sure about anything. I really don't think it's a fuel pump or line issue though. My memory isn't really helping but I am fairly sure I used a 5.3 OS for the fuel/timing segments.

I'll have to go take another log to test things I guess. When you say trims you mean PE? I haven't touched that (yet).

I'm fairly sure the wideband is correct because I'm starting to get watery eyes when I drive it now. (I don't have the exhaust dumping out proper yet.) Although this isn't usually a problem because I don't have a top or doors on it usually although I do at the moment.

Everything read normal when I was trying to do the CALC.VET tuning according to the howto at EFILive.

I'm pretty convinced now though that it was already starting to read too lean at that point and that's why I wasn't able to tune it properly then.

[steveo]

I've checked a couple times for vacuum leak but am contemplating building a smoke machine and doing a smoke test at this point. That's all that makes sense as to why it's so lean in my brain.

that makes the total opposite of sense.

as you rev the engine your manifold vacuum decreases substantially, and the airflow through a large opening (your throttle plates) increases substantially. this means that the percentage of airflow of a small to medium sized secondary opening (your vacuum leak) can contribute goes down big time. you are experiencing the opposite, going lean at higher RPM but normal at low RPM. if you had a vacuum leak big enough to affect anything off-idle it would also be idling like crap and you haven't mentioned that.


I'm pretty convinced now though that it was already starting to read too lean at that point and that's why I wasn't able to tune it properly then.

again, unless you're running a non-factory calibration on a non-factory engine, this is a diagnostic project, not a tuning one. i'm starting to think one of those conditions isn't true, or something else basic like the injectors are not correct or have failed.

the other oddball thing is you say it has tons of power. there is no way an engine burning such lean AFRs is going to have good power.. i don't know much about the 5.3 but that generation of ECM doesn't use active fuel management, does it?

[jeeper]

Thanks again steveo.

Just to be clear I'm not trying to tune around any problems. I'm just trying to correlate symptoms. I'm just a shade tree mechanic. I'm trying to say I think I discovered I had underlying issues while I was trying to tune the PCM initially. That's when I decided I needed to step out of EFILives forum and look elsewhere for help. I have not (and will not) try tuning the PCM until I have the underlying issue corrected.

I obviously wasn't thinking clearly about the vacuum leak. I was just grasping at straws on my keyboard...

The engine does seem to idle quite well and is always rich on the wideband. It also has a lot of power even when it is posting 17-18 AFR on the wideband. I'm thinking I will try to log some more to verify what other conditions are showing in the PCM while the wideband is reading so lean.

[B52Bombardier1]

What does a spark plug look like on the internal white porcelain at the tip? It should be bone white if it is as lean as you think it is?

Fuel trim? Long Term Fuel Trim (LTFT) and Short Term Fuel Trim (STFT) - these are indications from your PCM that tell you how much your fuel injectors are struggling to keep the mixture close to a stoichimetric 14.7 to 1 ratio. Any of the good Android or IOS OBD 2 code readers can tell you these values. My favorites here using Bluetooth on Android are OBDLink, MotorData OBD, and OBD Fusion. All are very inexpensive or free though to gain access to the extended parameter ID's might cost you 5-10 bucks.

Rick

[In-Tech]

The engine is completely stock. I did mount the MAF directly to the intake and it has a high flow air cleaner in a cold air intake setup.
I am assuming you have a 5 wire Delphi MAF? Please tell me it is NOT mounted directly to the throttle body? If the ducting and pcv system is hooked up correctly, a stock 5.3L engine will move about 225 grams per sec through the MAF at ~5000 WOT. If it is substantially lower than this, the MAF is bad, quite common. The gm/sec at warm idle neutral/park with a stock 5.3L should be ~6 and at 2500rpm in neutral/park it should be ~23-25.

If you need one, do NOT buy a rebuilt/reman MAF, they can be worse right out of the box, even AcDelco reman.
DELPHI AF10043 is usually reasonable priced.

[jeeper]

What does a spark plug look like on the internal white porcelain at the tip? It should be bone white if it is as lean as you think it is?
Rick

I will pull a couple plugs today. At least one from each side.

I do have a bluetooth OBD scanner. I will try it today to see what it will show for free. Otherwise I was thinking about buying Torque. Would that work? I can also hook up my V2 and see in real time what is happening on my computer I think.




I am assuming you have a 5 wire Delphi MAF? Please tell me it is NOT mounted directly to the throttle body? If the ducting and pcv system is hooked up correctly, a stock 5.3L engine will move about 225 grams per sec through the MAF at ~5000 WOT. If it is substantially lower than this, the MAF is bad, quite common. The gm/sec at warm idle neutral/park with a stock 5.3L should be ~6 and at 2500rpm in neutral/park it should be ~23-25.

If you need one, do NOT buy a rebuilt/reman MAF, they can be worse right out of the box, even AcDelco reman.
DELPHI AF10043 is usually reasonable priced.

It is a stock GM MAF. On the grounds that I might incriminate myself I probably shouldn't tell you I did mount the MAF directly to the throttle body. I'm assuming now that it's a bad idea? Is it a bad idea because of reaction time? Or maybe the air temperature is off because of it? I will relocate it if needed. I will also try testing it today when I'm looking at fuel trims.

[dave w]

The information below if from the EFI Live Tutorial section. It's a good plan to copy / paste the High Octane tables into the Low Octane tables when going MAFLess without "Boost".

dave w

Custom OS and 2/3 Bar Tutorial EFILive V7 Tuning
Tool




Going MAFless
When fitting a 2 or 3-bar MAP sensor you must disable the MAF sensor. It is possible to leave the
MAF sensor in place. This will need to be done on the 85mm MAF as the Intake Temp Sensor is located
in the MAF housing. Alternatively, you could relocate the IAT using on older style IAT sensor.
Even with the MAF still in place, the PCM must be forced to ignore the MAF signal.
To disable the MAF sensor:
Set the Engine Diagnostics->Engine Diagnostics->MAF->Parameters:
• {C2901} MAF High Frequency Fail 1: 1Hz
• {C2902} MAF High Frequency Fail 2: 1Hz
If calibration {C2902} is not available in the operating system that you are using, then ignore
this step.
• {C2903} MAF High Frequency Fail Limit: 1
• {C2907} MAF Test Min Engine Speed: 300 RPM
• {C2908} MAF Test Min Run Time: 0.1 seconds

Set the Engine Diagnostics->Engine DTC processing Enablers:
• P0101 ‘C’ Non Emissions
• P0102 ‘C’ Non Emissions
• P0103 ‘C’ Non Emissions

Set the Engine Diagnostics->Engine DTC MIL Enablers:
• P0101 ‘No MIL’
• P0102 ‘No MIL’
• P0103 ‘No MIL’


When going MAFless and/or boosted on vehicles with Electronic Throttle Control, you will most
likely need to increase {C6101} ETC Predicted Airflow, by significant amounts to stop the PCM going
into reduced power mode.

Set the
Transmission Diagnostics->Transmission DTC Fault Max Pressure Enablers
• P0101 ‘No’
• P0102 ‘No’
• P0103 ‘No’

Set the Transmission Diagnostics->Transmission Failsafe Enablers:
• Set all airflow related enablers to ‘No’ to prevent the transmission from going into failsafe
mode due to the MAF being disabled.


































































support@efilive.com - 15 -
www.efilive.com

[jeeper]

I spent a few minutes and removed a couple spark plugs. The tips were light tan but the plugs were not new when I started this swap. The engine had these plugs in it when I swapped it in so I don't know if it really matters much what they look like now.

I took another short video today.

https://www.youtube.com/watch?v=Hm9BDZc3pjk

Some of the gauges I selected don't appear to be working but it does show short term fuel trims.

[B52Bombardier1]

Hello,

I have Torque but I'm not much of a fan because it is incomplete on parameter IDs for me. Yet it did show that your O2 sensors are working and your fuel trim is not maxed out. I've seen my LTFT maxed out at +25 due to chaotic air at the MAF screen until I changed out the tubing headed into the throttle body. Now my fuel trim values look much like yours. You definitely are not outpacing what your fuel injectors can handle.

So I'm still puzzled here but think the advice given for a bad MAF might still be correct. If you don't want to pay full price for a new MAF, go to the junk yard and buy another one or two for cheap. They make great diagnostic tools in situations like this and if they work well, now you have spares.

Edit: It is odd that your Bank 1 and Bank 2 fuel trims mimic each other so closely - almost exact copies of each other. Mine vary a good amount between the two sides of the engine but are generally under +8 for LTFT and less than +5 for STFT.

Rick

[jeeper]

That wasn't actually Torque. It didn't seem to have a lot of PIDs. I ended up using OBDLink.

I'm going through the tune now and failing out the MAF to test. I'll report after I have tested it.

[jeeper]

Thanks dave w. I didn't really understand your post until B52Bombardier1 mentioned what it meant...

I set the MAF to 1Hz and tried it. It seems the MAF is causing my problem.
So is it common for the MAF to fail gradually?

Short video confirming it is not great but better with the MAF disabled. It doesn't idle as good but it is way less lean.

https://www.youtube.com/watch?v=NdR9_PBbMns

[dave w]

On most operating systems, when the MAF is set to 1Hz the low octane table is default. Try copy / paste high octane tables into low octane tables.

dave w

[jeeper]

So I did a couple things this evening.

I started off by taking it for a test drive to watch the AFR under a real load. At WOT it still goes about 15 AFR which is a bit lean. I decided I'd adjust the octane tables next.

I copied (with labels) and pasted (with labels) the high octane table into the low octane table and did a cal-flash. I tested it in the driveway but didn't road test it yet. It doesn't help the idle at all but I haven't tested it for power on the road.

I then decided I'd relocate the MAF from the throttle body to just after the air filter. I also borrowed the MAF from my sons TJ that I installed a 5.3 into (his Jeep isn't done yet). I reloaded my original tune and tried that revving it in the driveway. It still runs lean that way but not as bad as my MAF was causing. It would sometimes make it to 16 AFR but wouldn't stay there for long.

At this point I'm wondering if I'm actually ready to try tuning it?

[steveo]

no

15:1 at wot is really really lean

a stock gm calibration would be 13:1 or richer

thats a pretty massive fueling error

dont tune it

one more time

a stock engine with a stock tune will maintain a good AFR under all conditions unless something is broken

in fact except for a very small performance edge and tuning out the emissions stuff of accessories you aren’t using, you shouldn’t have to tune it at all

[B52Bombardier1]

Hello,

I agree with Steveo. Unless you have swapped in a radical cam, changed the intake manifold to something that flows a lot better or put in a different type of fuel injector, you should not have to make tuning types of changes to your operating system. The 5.3 in my El Camino got a set of headers and that change did not require anything to be changed in the OS. The PCM is quite adaptive, within reason.

From what you have described about your Jeep so far, it should not need anything changed from a performance standpoint. Maybe a slight change to Power Enrichment but I would not worry about that now for the little benefit that it brings to performance. Most of your efforts will consist of killing off MIL / CEL things like EVAP, EGR, catalyst overheat, rear O2 sensors, etc. I also have a long list of DTC's that get turned off.

Rick

[dave w]

I'm wondering if the injector programming is correct?

dave w

15770

15771

[jeeper]

I appreciate you guys trying to help me sort this out. I also appreciate you being patient with me. I know what it's like trying to help someone who you're sure is dense... And I am sometimes dense.. thick skull.

I really don't think it's a hardware problem right now. Especially after seeing such a marked improvement simply by failing out the MAF.

I think maybe I should "start over" with a stock OS.

I will look for my "original" OS that came on the computer I got with the engine. If I saved it, I can compare it to what I loaded into the pcm to convert it to a manual transmission OS. My problem is the original laptop I used to program it died and I don't know if I got everything off it. I can probably find a stock 2000 Silverado OS online somewhere if I don't have my original.

Does that sound like a reasonable next move?

[dave w]

The 12212156 OS is a good foundation to build on.

There are two types of injectors used on the 5.3 Liter, with very different injector parameters programmed into the flash, see pictures in the above post. Injector parameters are very important. Using the wrong injector parameters will cause ENORMOUS HEADACHES and possibly create dozens of posts about "what is wrong." A classic example of using the wrong injector parameters occurs when a LS1 5.7 intake has been installed on a 5.3, but the 5.3 flash was not updated with LS1 5.7 injector parameters.:mad1:

There are a couple different strategies for building a custom flash. Start with a 5.3 flash and segment swap in the manual trans section or start with manual 4.8 / 6.0 and segment swap in the 5.3 section. I've tried both strategies, with varying success. Ultimately, the most successful flash "for me" started with a 4.8 manual flash, and updated with "hand picked" not segment swapped 5.3 parameters.

dave w

[jeeper]

I believe I found the original tune that was on the computer that I believe to be the stock 2000 Silverado computer. It was OS 09381344. In table B4001 it shows the injector flow rate at 3.1250.

In the current OS on that same computer it shows the same flow rate table as 3.1797.

So should I change the flow rate in my 12212156 OS to match 3.1250 instead of 3.1797?

[B52Bombardier1]

That would be a good start to see if anything changes. I have a good working original copy of 12212156 here and an already edited copy with VATS removed, etc if you need it.

Rick

[dave w]

according to the injector calculator I'm using:
3.125 g/sec = 24.8 lb/hr
3.1797 g/sec = 25.2 lb/hr

Injector base pulse width (BPW) is calculated using injector flow. Increasing the injector flow will cause the computer to lower BPW = Less Fuel. Decreasing the injector flow will cause the computer to increase BPW = more fuel.

If you want more fuel change the injector flow to 3.125.

Maybe we shouldn't be so quick to say the flash is 100% correct?:innocent2: Let's see what happens when the injector flow is set to 3.125:thumbsup:

dave w

[steveo]

a difference in injector flow of less than 2% wouldn't be causing fueling errors in the range of 20%

[jeeper]

I just verified changing the flow rate did not correct my lean condition. I then did a MAF fail to see it maybe the second used MAF is contributing to the lean condition. It is not. I am still running lean as soon as I go above idle for a second or two.

[dave w]

a difference in injector flow of less than 2% wouldn't be causing fueling errors in the range of 20%

I agree 100% with you steveo, 2% wouldn't be causing 20% errors.

Now, I have to wonder what fuel pressure regulator is being used, return-less or vacuum referenced? The injector flow rate for a return-less fuel pressure regulator is linear with different flow rates in each cell. If a Corvette fuel filter / pressure regulator is being used, then having all fuel injector cells the same flow rate 3.125 would be incorrect.

dave w

[jeeper]

It is a new return style vacuum referenced regulator.

Would the MAP sensor play into this at all? How would I test it? What is a "normal"reading for a stock engine at idle and say 2000 rpm?

[steveo]

the map sensor is not a likely failure point. i’ve seen a dead one once in my life. the correct way to test the sensor would be to apply vacuum to it and datalog with engine not running, or use a mechanical gauge while observing the data. also when off it should be whatever your atmosphere pressure is, about 100 kpa near sea level.

[dave w]

I suppose there is the option to set the injector flow rate to 3.00 or lower to see what happens. The odd thing is, setting the injector flow rate lower than the factory specification on the factory stock injectors would mean .... the engine likes a rich mixture. Why would a stock engine need a rich mixture?

I wonder what cylinder balance test might indicate?

dave w

[dave w]

It is a new return style vacuum referenced regulator.

I wonder what would happen if the vacuum line was disconnected from the fuel pressure regulator? Would anything change with the ARF's at different RPM's?

dave w

[jeeper]

I've been playing with this for a few hours today. I actually set the flow rate lower by 20% thinking that may help. It didn't. I tried all sorts of things. I tried modifying the VE by 20% by both adding and subtracting 20% from the stock table. Nothing seems to be allowing it to run rich.

At this point I am disabling vats and reloading the original OS back on the computer and testing it (if it will run at all due to the manual trans swap). My thinking is if it will start and run on the original OS I can see what the AFR is then. I'm guessing it will start because I am not using the GM computer to start it I am using the Jeep computer to crank it over.

Before I do anything though I will unplug the vacuum line from the new regulator to see what happens.

[jeeper]

edit: I did unplug the vacuum line but that didn't change anything. I tried it before and after OS change.


At this point I am disabling vats and reloading the original OS back on the computer and testing it (if it will run at all due to the manual trans swap).

This didn't help either. It runs fine with the "stock tune" but is even more lean now including at idle... edit: when I say runs fine I mean idles smooth as glass and sounds really good.

I'm 100% confident I'm getting good fuel pressure and I'm 95% sure I'm getting enough volume to the rail because the pressure doesn't drop when I rev the engine with the gauge connected.

That seems to leave only the injectors left? Or maybe I have a faulty wideband?

This isn't really "fun" anymore it's frustrating...

[jeeper]

This didn't help either.

Wait a minute. Time for a dumb luck update.

I was ready to step away from this for a couple days. I decided I'd take my dog to the park for a swim in the river. My dog loves to swim and it is hot here for the last few days. I took the Jeep. It still has the stock original Silverado 9381344 OS on it with VATS removed and some automatic transmission parameters changed. I watched the wideband hover around 14.7 to 15 all the way there.

Since I was low on fuel I decided I'd better fill up before I went home so I drove from the park to the gas station. Again it was running between 14-15. I wasn't really watching it that close. On the way home from the gas station is when I noticed (and was probably the first time I tried) at WOT I was running 12 AFR. I was a little stunned so I tried it several more times. Sure enough on this OS when I go WOT it goes rich.

Now I have a starting point? I can now be sure I am getting enough pressure and fuel flow to the engine at least...

[jeeper]

So at this point I don't really understand why I would be running lean at every RPM/throttle position except WOT. What could be broken? If it goes rich at WOT doesn't that prove I'm getting enough fuel and enough pressure? I suppose I can hook the gauge back up and record it again but I'm pretty sure it isn't a "fuel delivery" problem.

Anyone have any suggestion on what I should be looking for? I'm probably going to step away from this for the weekend but that doesn't mean I won't be thinking about it...

[dave w]

Most members would agree, when cruising, AFR's ranging between 14.2 to 15.2 are good. AFR's going above 15.5 are lean. Warning: Prolonged AFR's above 16.2 will eventually damage the engine.

dave w

[jeeper]

Thanks dave w. I was just looking at B3601 and seeing it is telling the computer to run at 14.68. Hitting 15 didn't seem horrible to me.

I was curious if I tried setting that a little on the rich side what would happen? I was thinking telling it to try for 14 instead?

If I watch the AFR closely on the stock OS I see the AFR dip to 13ish and rise slightly above 15 or sometimes 16 briefly while accelerating. Once I'm at cruise speed it settles in pretty close to 14.7 on average.

I think I'm going to run this for a while and keep watching it. It doesn't feel as powerful as the other OS tune but it idles really good and seems smooth all around.

I also hope to discover what else I must have missed when I changed the OS to 12212156.

[jeeper]

I ended up driving the Jeep quite a few times this weekend. It seems to be running great and doesn't go lean with the current OS. I'm not sure if I'm going to change the OS back on this computer. I don't really have any need to tune this beyond where it is as far as I'm concerned. It seems to stay very close to stoich under all throttle conditions. And there is almost no exhaust smell. It idles very smooth as well.

At this point though I am wondering why I need a vss because I can't tell how I would benefit from the GM computer knowing the vehicle speed.
I am also not understanding why I need a manual transmission OS. This jeep seems to be fine with the original automatic OS with the torque management disabled.

I will probably update this thread once I have figured out why it was running so lean with the other OS. Or maybe to ask questions about what I find. I am planning to follow through with it mainly as a learning exercise.

Thank you all for the help with this.

[steveo]

there may be certain conditions where it will think you're standing still and not enter a certain mode. for example, it shouldn't be stoich under heavy throttle, it should be quite a bit richer as it enters power enrichment. is it going into power enrichment? is there a minimum vehicle speed to enter power enrichment in your application?

[jeeper]

It does enter PE. If I stab the throttle it drops to ~12 and never gets above 13 at WOT. If I accelerate slowly it stays close to 14. I should probably make a video to show what it is doing.

I have PE delay {B3608} at zero and PE Modifier by RPM {B3618} is at default values. I haven't found any vehicle speed reference for PE anywhere under Fuel>Mixture. It is entirely possible I missed it or it is elsewhere though. I do see speed reference under DFCO.

[dave w]

At this point though I am wondering why I need a vss because I can't tell how I would benefit from the GM computer knowing the vehicle speed.
I am also not understanding why I need a manual transmission OS. This jeep seems to be fine with the original automatic OS with the torque management disabled.


It might not be necessary to use a VSS. When the tuning has challenges, adding a VSS is a good plan. There are several parameters that use VSS information, like DFCO.

dave w