98 Secondary VE MAF Help

[ralmo94]

I have a 1998 K2500 7.4 454 4l80e, with the black box vortec PCM ECU ECM Computer or what ever your supposed to call it.

I Use HP Tuners for it, recently got the Wide Band Hooked up, and reporting with the EGR position pin.

I have found very little in the way of tutorials or write ups on tuning these.

What I have found, states that when you fail the MAF and place it into speed density, it only uses the lower resolution secondary VE table.

I did that and got the secondary VE close enough for me.

SO what I have read is the accepted method, is to copy secondary VE to main VE, and interpolate between.

When I did this, It seemed still way off.

I had taken the aproach that the MAF should be correct as there was no intake modifications, it's stock with stock filter, and clean.
So I have been adjusting the main VE table with the MAF on. Seems to be beter, but i still am having dificulty getting it close in few spots. Light load cruise seems to be leaner than commanded, and decel seems to be extremely rich. Decel was showing around 10:1 I've got it a little better, but still pretty rich around 12:1. At one point I looked at logs to see where the maf was on decel, and leaned it about how much I was off.

I have been doing all this open loop. Closed loop seems to target a little rich around 14.1 - 13.9 on the wide band standard gas scale.
Narrow Bands probably need replaced, but I would rather get it dialed in and just keep it open loop, as that is the only way to use lean cruise with one of these, at least as far as I know.

I have been able to edit the Dynamic Airflow settings and create a MAF only tune, verified by zeroing out both VE tables. If I could somehow use those settings to use Main VE only, I think I wouldn't have any problems. Every attempt has produced no running.

So I am wondering If any one has messed with these much, If so, what was your method?

I am also wondering if I should load a Maf only tune in, and Make sure the Maf is correct, but I am afraid of loosing progress, and I don't want it to get to lean bearn limit and die on the road, I guess I could start by adding 10% to the Whole Maf table to keep from that.

Or just Fail the Maf and run the low res secondary VE?

Am I over thinking all of this?

What what would you do to dial this thing in?

[Fast355]

I have a 1998 K2500 7.4 454 4l80e, with the black box vortec PCM ECU ECM Computer or what ever your supposed to call it.

I Use HP Tuners for it, recently got the Wide Band Hooked up, and reporting with the EGR position pin.

I have found very little in the way of tutorials or write ups on tuning these.

What I have found, states that when you fail the MAF and place it into speed density, it only uses the lower resolution secondary VE table.

I did that and got the secondary VE close enough for me.

SO what I have read is the accepted method, is to copy secondary VE to main VE, and interpolate between.

When I did this, It seemed still way off.

I had taken the aproach that the MAF should be correct as there was no intake modifications, it's stock with stock filter, and clean.
So I have been adjusting the main VE table with the MAF on. Seems to be beter, but i still am having dificulty getting it close in few spots. Light load cruise seems to be leaner than commanded, and decel seems to be extremely rich. Decel was showing around 10:1 I've got it a little better, but still pretty rich around 12:1. At one point I looked at logs to see where the maf was on decel, and leaned it about how much I was off.

I have been doing all this open loop. Closed loop seems to target a little rich around 14.1 - 13.9 on the wide band standard gas scale.
Narrow Bands probably need replaced, but I would rather get it dialed in and just keep it open loop, as that is the only way to use lean cruise with one of these, at least as far as I know.

I have been able to edit the Dynamic Airflow settings and create a MAF only tune, verified by zeroing out both VE tables. If I could somehow use those settings to use Main VE only, I think I wouldn't have any problems. Every attempt has produced no running.

So I am wondering If any one has messed with these much, If so, what was your method?

I am also wondering if I should load a Maf only tune in, and Make sure the Maf is correct, but I am afraid of loosing progress, and I don't want it to get to lean bearn limit and die on the road, I guess I could start by adding 10% to the Whole Maf table to keep from that.

Or just Fail the Maf and run the low res secondary VE?

Am I over thinking all of this?

What what would you do to dial this thing in?

Fail the MAF, tune secondary VE, interpolate and get the VE tables smoothed out.

Your thinking is wrong on the MAF atleast every vehicle I have ever tuned I have had to tune the MAF tables as well.

Once you get it running well on speed density with the MAP and have the MAF tuned, turn the blend back on. I generally log both for errors and make equal adjustments to both from there. Generally it is pretty close at that point. I shoot for long term fuel trims slightly in the negative. 0 to -5% is generally a good target. If the fuel trims are a positive value when you enter PE the PCM will add that percentage of fuel across the whole RPM range.

Too rich decel can be injector values that are not right for the injector if you have swapped injectors.

14.1 is stoich on 10% Ethanol. If you have 10% ethanol in your fuel set your stoich value to 14.1.

[ralmo94]

Fail the MAF, tune secondary VE, interpolate and get the VE tables smoothed out.

Your thinking is wrong on the MAF atleast every vehicle I have ever tuned I have had to tune the MAF tables as well.

Once you get it running well on speed density with the MAP and have the MAF tuned, turn the blend back on. I generally log both for errors and make equal adjustments to both from there. Generally it is pretty close at that point. I shoot for long term fuel trims slightly in the negative. 0 to -5% is generally a good target. If the fuel trims are a positive value when you enter PE the PCM will add that percentage of fuel across the whole RPM range.

Too rich decel can be injector values that are not right for the injector if you have swapped injectors.

14.1 is stoich on 10% Ethanol. If you have 10% ethanol in your fuel set your stoich value to 14.1.

Thank you so much for the reply.

I still have the secondary VE that seemed to be close. I can go ahead and interpolate it into the main VE. When I did that last time it seemed way off, I am guessing that was more likely the MAF being off then? It sounds like I need to run a MAF only tune and dial that in.

The injector settings could very well be off. When I bought the truck, it had the mild hot start issue, and got a lot worse real quick. I used a set of "balanced" injectors from Ebay, that were supposed to be the Bosch equivalent of stock. The injectors I took out were 6 hole injectors, and the new ones were 4 hole. The plenum had leaked, a couple bolts were loose, and not even touching. At least 3 injectors had torn orings. I'm pretty sure someone else had been in there before me for the same reason. The Fuel Pressure Regulator was shot. Drove it about a year, ended up changing the lower manifold gasket, distributor, and rod bearings.

I asked the seller of the injectors if they had any specs for them, they didn't know, except they are supposed to be stock replacements. I have no idea what to mess with in the injector settings. The only one that makes a lot of sense to me is lb per hr. Its at stock 22lb. I wouldn't know where to start adjusting them.

As far as the E10, I know what you are saying, it takes 14.1 parts air to one part fuel to get lambda 1. The wide band guage displays the 100% gas scale of 14.7 = lambda. All the gauge knows is a scale of lambda, but the computer needs the correct math to get lambda. So when displaying 14.1 on the wideband, that is lambda of about .95 with an actual AFR of 13.3. Or as I understand, lambda of .95 is 5% rich.

I did have the stoich set at 14.13, and it didn't seem right. I put it back to stock 14.7 and it seemed a lot better. Plus with it at 14.7, it is easier to log AFR error. I can set it up for 14.1, but its harder to get the laptop to display the correct scale

I am willing to change injector settings, but have no idea what to start with. I believe that means I pretty much need to start over with VE also?

Thank You,
Ryan

[ralmo94]

https://www.ebay.com/itm/Reman-Genui....m46890.l49292

This is a link to the injectors I bought. Same set still available. Price went up, I only paid $94

I don't know if any of the part numbers mean anything to anyone

Thanks

[Fast355]

https://www.ebay.com/itm/Reman-Genui....m46890.l49292

This is a link to the injectors I bought. Same set still available. Price went up, I only paid $94

I don't know if any of the part numbers mean anything to anyone

Thanks

Those are injectors for a 3.8 Buick non supercharged. L36 engine code. Should be able to find a stock GM calibration and transfer over the injector data.

Had a similar issue years ago with my 97 350 Express van after installing the later model MFI spider in place of the poppets. Got the correct injector values out of an 03+ Astro van 4.3 that came from the factory with the upgraded style of injectors.

[ralmo94]

Those are injectors for a 3.8 Buick non supercharged. L36 engine code. Should be able to find a stock GM calibration and transfer over the injector data.

Had a similar issue years ago with my 97 350 Express van after installing the later model MFI spider in place of the poppets. Got the correct injector values out of an 03+ Astro van 4.3 that came from the factory with the upgraded style of injectors.

Thanks I appreciate it!

I was able to find a stock tune on HPT site for a 97 Buick LeSabre. I would imagine a LeSabre would not be SC, but every 3800 file I found for Camaros, Or Pontiac, Holden, all had VE tables that go up to 140 kpa?

They also have a flow rate table based off of MAP. What home work I did says that I don't need that because I have vacuum referenced pressure regulator, and a N/A 3800 would have also, and a flat table, all the same values. So the 3800 buick was 23.3 lb hr in every cell of the table.
My vortec has a voltage flow rate multiplier and a single value for flowrate.
Stock setting is 22.2 lb hr with 11.5 vlts - 13.5 vlts multiplier of 1 and 14.5 vlts of 1.006.

Truck usually runs about 14.5 volts or so
22.2 * 1.006 = 22.3332 Seems about right to me?

a differnce I seen was the offset settings.

3800v6 has a refrence to kpa and pulse width, and another table to volts.
Vortec only has volts. and a offset setting

Vortec has short pulse limit, and a table of short pulse adder.
I remember reading that someone zeroed out thier adder table and changed the pulse limit to 1. But I don't know what injectors they were using\

3800 doesn't have a short pulse limit or adder.

Vortec has min PW set at 0.788 ms. 3800 does not have any kind of value for that

Seems like when I was on decel and it was rich, the PW never dropped below 2.4 ms, wich happens to be what the short pulse limit is set at.

So I scaled the voltage offset to match the 3800. was a little different as the 3800 has whole numbers for voltage and vortec has halfs 12 13 14 vs 11.5 12.5 13.5

So I interpolated values between 12 and 13 to get 12.5. Did that for the whole table.

I am thinking other than that, should I zero out the short pulse stuff? I don't see much else to change.

Thanks for all the help

[ralmo94]

I just realized I don't think I did the offset correct

3800 has it all in ms , while vortec has a ms value, and a multiplier.

That is going to take me a few minutes to get squared away.

[ralmo94]

I just changed the ms value to 1. Then all the multiplier values will be * 1 ms, so they should equal the same as if it was ms instead of a multiplier.
I hope.
Seems like that was too easy to fix.
Feel free to let me know anything I did wrong, other than grammer, I know I'm bad at spelling and grammer. lol

[ralmo94]

Doing more homework, I found something from what appears to be a honda site.

Shows how to set up new injectors, and that it might be different than advertised specs.

RELYS on having a good time in stock injectors first thou.
IF ITS OK,. I'll post a link to it.

I'm pretty sure it's ok to paste the info though, so here it is.


How to Set Injector Flow-Rates and Set Injector Dead Times
Anyone who as installed aftermarket injectors before probably ran across the issue of not having accurate injector dead time values to enter into their tuning software or having an engine run too rich or too lean using the fuel injectors advertised flow-rates. Having accurate injector dead time settings (also known as injector lag time or latency) is critical for a quality idle as well as maintaining air/fuel ratios when there are lots of accessory loads on the engine (ie: headlights, heater, etc.). Here is our recommended method for setting flow-rates and getting the dead times dead right:

1. Do a full tune using stock/OEM injectors with OEM injector dead times. If you are tuning a boosted car, etc. that the stock/OEM injectors cannot provide enough fuel for, just tune the idle and part throttle areas of the fuel and ignition maps fully.

2. Turn off all accessories (headlights, heater, stereo, etc.)

3. Hold the throttle steady at 3,000 rpm after tune is complete and take note of your air/fuel ratio. WRITE IT DOWN.

4. Allow the engine to idle and take note of your air/fuel ratio. WRITE IT DOWN.

5. Install your aftermarket fuel injectors.

6. Set your injector size setting in your tuning software to the new injectors' published flow rate/size.

7. Hold the throttle steady at 3,000 rpm and adjust the "injector size" setting higher or lower until you reach the same air/fuel ratio that you wrote down in step 3 above. Adjust the injector size lower to richen/increase fuel. Adjust the injector size higher to lean/decrease fuel. Upload or program the changes to your ECU and repeat this step until you reach the same air fuel ratio as in step 3. You will most likely end up with a value that is different than the published injector size, this is correct and not an issue.

8. Allow the engine to idle. Now go to your injector dead time/latency tables and take note of the injector dead time value for the voltage that you are currently seeing in your tuning software. For example, if you are currently seeing 14.0 volts, only adjust the box for 14.0 volts. Adjust the value in the box for the voltage you are currently seeing in your tuning software higher or lower as needed until you reach the same air/fuel ratio that you wrote down for step 4. If the engine is running richer than the value from step 4, decrease the dead time value. If the engine is running leaner than the value from step 4, increase the dead time value. Upload or program the changes to your ECU and repeat this step until you reach the same air fuel ratio as in step 4.

9. Turn on your headlights, heater, etc. to produce an electric load on the engine until you see your voltage go lower (ie: down to 12 volts). Now go to your injector dead time/latency tables and take note of the injector dead time value for the voltage that you are currently seeing in your tuning software. For example, if you are currently seeing 12.0 volts, only adjust the box for 12.0 volts. Adjust the value in the box for the voltage you are currently seeing in your tuning software higher or lower as needed until you reach the same air/fuel ratio that you wrote down for step 4. If the engine is running richer than the value from step 4, decrease the dead time value. If the engine is running leaner than the value from step 4, increase the dead time value. Upload or program the changes to your ECU and repeat this step until you reach the same air fuel ratio as in step 4.

10. You can now either calculate or interpolate values to the rest of the boxes, or you can work on other boxes by producing even further load (ie: disconnect the battery and allow the engine to run on the alternator only, etc.

You are all done. You can now enjoy your dead-on injector dead times and accurate air/fuel ratios. Happy tuning.


I'm thinking about going back to stock VE and MAF and attempting this method, but that would assume stock being right on.

I think first I'm going to try the settings from the 3800 tune first, turn closed loop back on and see how far off it is. Any thoughts for consideration, let me know

[ralmo94]

Just in case anyone might be thinking they will learn from experience I thought I would update everyone here. And maybe someone can tell me if I did something wrong.

I zeroed out the short pulse adder. I don't think that was right, but seemed like it at the time. I drove about 100 miles pulling a trailer. It didn't seem like much had changed.

So I began studying over both tunes, the Vortec and the 3800 buick.
What I realized is while the 3800 doesn't have a table titled short pulse adder, it has a table that pretty much does the same thing. OFFSET vs PW vs MAP.
My short pulse limit pretty much setts when to use the sp adder table, range 0 - 4 ms. table defined to 3ms.

The Buick has an axis of PW ranging from 0-4 ms. Another thing I realized, it has the same values set for different Map. Seems to me more evidence that it was a N/A tune.

So I began inporting the values in my vortec. Was different, but didn't make sense as adding more injectoro time would result in a richer AFR and more fuel. I was already rich on Decel, But as I was finishing up, I realized most of the values in the 3800 seemed to NEGATIVE numbers. So now it makes sense though , the short pulse adder, needs negative numbers for these injectors, so in effect I guess they are more efficient injectors than 7.4 Multecs, in stead of adding open time at short pw values, it needs less open time.

I also ralialized something else I did wronge while reading what I had posted.

I didn't look close enough I guess. Was thinking 23.3 was the same as 22.3. oops.

I guess when I get the flow rate correct, I should be able to start over tuning my VE tables and Maf. .

Fired it up last night, turned closed loop back on, seemed to jack the fuel all over the place, I'm thinking I might stick with open loop for now.

Maybe that was because of my mistake with flow rate, but was surging all over like a bad vacuum leak or something. kinda bad.

Let me know if all this makes sense or not, and please let me know if anyone thinks I did something wrong.

Thanks

[ralmo94]

here's an update,
Put another couple hundred miles on the truck yesterday.

Open loop.
Turned stock MAF and VE blending on with stock tables.

Tune was pretty far off, I reflashed 3 times before leaving town.

Another reflash after about 30-50 miles, and another at about 100.
Reflashed and filled up. Truck seemed alot better and was running a lot closer to correct.

MPG on that tank was 12.9.
Not bad for a 454 out of tune, considering when I bought it the best it could do was 12, with easy pedal hiway gas station to gas station driving. You know optimal. This route was through a mountain pass changing elevation of about 2500 ft.
Plus I put the pedal down a few times for the data log.
Went another 100 miles back home without another reflash. Same route.
My wide band started acting up about halfway, so open loop logging might be over until resolved.

Filled up when I got back and that tank produced an MPG of 14.5.

I think I am close enough now to finish it up with closed loop.

This time I did not fail the MAF and tune secondary VE. Just started out with main and MAF. Applied changes to both at the same time. Had thought a while back that might work good, but never got enough of a chance to check with mechanical issues. That method seemed to work very well.

I think I am going to use my last open loop log,then turn cl back on and see how it does.

All in all I think the injectors are set up correctly, or at least goodish enough.

[Fast355]

here's an update,
Put another couple hundred miles on the truck yesterday.

Open loop.
Turned stock MAF and VE blending on with stock tables.

Tune was pretty far off, I reflashed 3 times before leaving town.

Another reflash after about 30-50 miles, and another at about 100.
Reflashed and filled up. Truck seemed alot better and was running a lot closer to correct.

MPG on that tank was 12.9.
Not bad for a 454 out of tune, considering when I bought it the best it could do was 12, with easy pedal hiway gas station to gas station driving. You know optimal. This route was through a mountain pass changing elevation of about 2500 ft.
Plus I put the pedal down a few times for the data log.
Went another 100 miles back home without another reflash. Same route.
My wide band started acting up about halfway, so open loop logging might be over until resolved.

Filled up when I got back and that tank produced an MPG of 14.5.

I think I am close enough now to finish it up with closed loop.

This time I did not fail the MAF and tune secondary VE. Just started out with main and MAF. Applied changes to both at the same time. Had thought a while back that might work good, but never got enough of a chance to check with mechanical issues. That method seemed to work very well.

I think I am going to use my last open loop log,then turn cl back on and see how it does.

All in all I think the injectors are set up correctly, or at least goodish enough.

Always good when their is positive change and a light at the end of the tunnel.

On my buddies dually we advanced the factory camshaft 4° and added long tubes built for a TBI 454 with dual 3" pipes off the collector, into new 3" high flow cats and then ran a 3" to 4" merge Y and a 4" diesel exhaust. Disabled the EGR and plugged the EGR pipe off at the intake manifold but left the valve for visual inspection reasons. His K3500 crew cab dually picked up alot of performance and was able to tow his car hauler with his ECSB 97 C1500 on it much more easily. I think he averages 16 mpg unloaded on the highway with a 4.10 gear and 37s. He has LS1 injectors in his.

[ralmo94]

Always good when their is positive change and a light at the end of the tunnel.

On my buddies dually we advanced the factory camshaft 4° and added long tubes built for a TBI 454 with dual 3" pipes off the collector, into new 3" high flow cats and then ran a 3" to 4" merge Y and a 4" diesel exhaust. Disabled the EGR and plugged the EGR pipe off at the intake manifold but left the valve for visual inspection reasons. His K3500 crew cab dually picked up alot of performance and was able to tow his car hauler with his ECSB 97 C1500 on it much more easily. I think he averages 16 mpg unloaded on the highway with a 4.10 gear and 37s. He has LS1 injectors in his.

16 in a dually. Wow.
Once I get a chance I plan on doing an inframe rering and cam swap with 0411 swap.
If I remember correctly, mine is a lot little tired with compression test of around 140.

Any idea what he gets towing? I have gotten the best of 9. Worst of 6.5, usually 8. Last tank with trailer on was about 8.5.

I have 3.73 and 265's. And she loves overdrive.

[Fast355]

16 in a dually. Wow.
Once I get a chance I plan on doing an inframe rering and cam swap with 0411 swap.
If I remember correctly, mine is a lot little tired with compression test of around 140.

Any idea what he gets towing? I have gotten the best of 9. Worst of 6.5, usually 8. Last tank with trailer on was about 8.5.

I have 3.73 and 265's. And she loves overdrive.

I think it gets 8-10 towing. He told me he towed a travel trailer at 90 not too long ago. So he tends to have a pretty heavy foot.

[ralmo94]

I think it gets 8-10 towing. He told me he towed a travel trailer at 90 not too long ago. So he tends to have a pretty heavy foot.

hope he has a away control hitch.

I was hoping to throw a set of headers on mine when I overhaul. Most of the ones I see say they fit pre 91 trucks. Any idea what actually fits the chasis?
I know, kinda off topic.

Anyways with closed loop active, I seem to be running a lot better, trims are real close. A few wash rinse repeat cycles and I should be moving on to timing. Only thing I seem to have as I turn cl on, is a slight hesitation from off idle. Seems to all but went away now though.

Does he run any lean cruise, or all closed loop? If you know.

Thanks ��