AFR in PE going rich, not sure why?

[KDS]

1999 camaro z28, 6.0 lq4, 243 heads, LS1 intake, TB, MAF, 40 lb bosch injectors, 255 lph pump, medium cam 224, 232 @ .50, headers, good exhaust. The car runs great on the street, great driveabilty and makes great torque and power to 5000 rpm. At the track, 1/4 mile is good (12.6 112mph) but it doesn't seem to pull hard to 6000 rpm like it should with this setup. Logs show that AFR goes richer than commanded after 5000 rpm and I can't seem to resolve it. I've attached a log and tune, the log has a full throttle run through to fourth closer to the end. The likeliest suspect for me is the injector data but this seems to only be a WOT high rpm problem, the rest of the time everything is great. MAF and Dynamic air flow are very close so i'm confident in the MAF and VE values. Any thoughts and suggestions would be a great help.

aug 6 2020 a.hplCamaro Aug 2 2020 6.0.hpt

[aaronc7]

LTFT are pretty high/jumping around. Looks like you just need to continue to dial in fueling. For the WOT stuff, do a single gear pull starting at a low rpm like 2000 rpm until redline. 3rd or 4th. 4th would be better but 3rd is fine if you can't take it up to that high of a speed. That will give good data to correct the high load areas of the MAF curve. Going thru the gears like that has too many transitions and such going on.

I just looked at the IFR table and it doesn't seem quite right either. The slope isn't correct for 0 vac to 80 kpa vac. Having good injector data is kinda a prerequisite before you really start tuning fuel. Do you have proper data for it was just guessing? At the end of the day you can "tune around" this sort of thing, but I would try to get correct injector data first, then go into the fueling correction stuff.

[KDS]

LTFT are pretty high/jumping around. Looks like you just need to continue to dial in fueling. For the WOT stuff, do a single gear pull starting at a low rpm like 2000 rpm until redline. 3rd or 4th. 4th would be better but 3rd is fine if you can't take it up to that high of a speed. That will give good data to correct the high load areas of the MAF curve. Going thru the gears like that has too many transitions and such going on.

I just looked at the IFR table and it doesn't seem quite right either. The slope isn't correct for 0 vac to 80 kpa vac. Having good injector data is kinda a prerequisite before you really start tuning fuel. Do you have proper data for it was just guessing? At the end of the day you can "tune around" this sort of thing, but I would try to get correct injector data first, then go into the fueling correction stuff.

Ok, I guess the gear shifting transitions are throwing me off a bit, the fueling seems to change as I go through each gear, with AFR getting richer as it runs up in third and fourth, but I assume that with the longer duration at the higher rpm's the high end MAF errors are more pronounced. The MAF flow values compared to the dynamic flow values are quit close in most cases, is this something I should continue to use for tuning accuracy?

I couldn't find any data for the injectors except for flow rating at 2 bar. Converted it to 58 psi and used that value for the 80 kPa cell, is that a correct assumption? I know the 0 - 80 kPa slope is less than with the stock injectors, I was tweaking the injector flows earlier on as part of the tune. The injectors are 0280155830 (Volvo) ,the stock ones 0280155931. Since these are the same family of injectors I was assuming same electrical characteristics, just more flow. If that is the case I can redo the injector flow rate table to mimic the stock injector 0 - 80 kPa slope.

[aaronc7]

Yeah, when you shift and get in and out of the throttle there's various fueling modifiers that kick in. By going WOT 2000-6500rpm or whatever, no modifiers are in play (only the MAF table, since MAP will be steady too). So now that the MAF table is basically the only variable in fueling, it's easy to correct the MAF table to get desired outcome.

Comparing MAF vs dynamic (VE) if they are in the same ballpark that's a great sign. Still would be a good idea to tune VE and MAF separately. But honestly if it feels good to you just normal driving, the VE table may already be good enough, and just focus on getting the MAF table spot on.

The injector flow table uses a weird axis, "manifold vacuum".

So 0 would be: [rail pressure] - [manifold relative pressure] or 58 + 0 = flow at 58psi
Cell 80 would be 58 + 11.6 (converted 80kpa to psi) = 69.6 psi

Ultimately the 80kpa cell should be the larger flow value.

So I guess your 39.5 value should be cell 0. This will in itself lean it out a little bit as the pcm will now command a smaller pulsewidth for a given airflow.

I would make that slight IFR change (only about 4 percent change), get a good WOT pull and go from there!

[KDS]

Ok that's good information, helps a lot. I'll recalculate the injector flow values through the manifold vacuum range and see what affect that has, then review the MAF.

[KDS]

Ok that's good information, helps a lot. I'll recalculate the injector flow values through the manifold vacuum range and see what affect that has, then review the MAF.

Recalculated the fuel curve using your suggestions and that made a big improvement. Top end AFR's are better and overall performance is better as well. The injector flow values changed from about +4% at 0 kpa to almost +8% at 80 kpa. Some fine tuning of the MAF and VE will get the tune in good shape. Thanks.

[aaronc7]

Glad to hear it! Yeah agree... you're probably as close as you're going to get for injector data, just proceed forward with VE/MAF tuning and go from there. You'll probably get to a point where you'll just want to call it "close enough" or you'll end up chasing your tail. Been there done that!