Engine bored to 8.1 L 9.5/1 compression, 36lb/hr injectors
1999_Suburban_K2500_7.4_3GNGK26J4XG260080_Injector_Displacement_IncreasedInjectorFlow_RealFlow_V.hptLog-0010-60080260080260080.hpl
Sorry, BBC, not CBB.
Hesitation about 3/4 way through log, can see LTFT flatline at -18, about 1500-2000 RPM sets rich codes for both banks and CEL.
Last edited by oldpartsnrust; 06-19-2023 at 02:39 PM.
Tell you what. I'll work on it get it going perfect. I'll let you decide if you feel like it's worth it.
Last edited by SiriusC1024; 06-20-2023 at 12:12 AM.
Works for me, I just hadn't gotten any reply. Thanks!
Open VCM Scanner then connect it. Vehicle Controls and Special Functions>Fuel> clear fuel trims and LTFT's
Cycle ignition.
Open VCM Editor. Write this tune.
Get a log. Add the Injector Duty Cycle channel. Try to do deliberate slow rate pedal movements. Populate as many STFT cells as possible.
I don't see that channel. I looked under 'engine' , 'fuel'. The only thing I see that may equate is the pulsewidth?Originally Posted by SiriusC1024
I loaded that tune and it started, but seemed to run really rich and the idle was surging quite a bit. Is this expected? Almost stalling out.
Last edited by oldpartsnrust; 06-20-2023 at 07:47 PM.
Yes it's expected. Do you have a log?
ok, no. I didn't drive it yet because of the surging and rich smell. I wanted to make sure it was expected.. I will try to grab a log tomorrow morning/afternoon. Thank you.
Well try it parked first. It'll be worth something to give a good baseline. Try to cover all the STFT cells you can thoroughly.
ok, should I warm it up with a cleaner tune, then clear Fuel Trims and upload this tune then go through throttle transitions? Should I do some in gear?
Yeah do it warmed up, cleared fuel trims, smooth throttle movements. If you can get into gears then do so. What do you mean cleaner tune? Use the one I posted. Don't worry it'll get there.
Ok, warmed it up, cleared LTFTs (I think, the button didn't seem to do much...) then loaded your tune and ran to collect log. I chickened out about 4,000RPMs, but got a couple to 4,800RPM once or twice. Did with even slow throttle, then tried to populate more of the grid by making quicker throttle, etc. Here's the log.
Alright run this one. Interesting to note you said it smelled rich. Log shows lean. Try to go for a drive. The longer the drive the more accurate the data. Same deal clear fuel trims.
Add Injector Pulsewidth and Cylinder Air Mass to the log. You have to be connected to add those channels. Maybe that's why you didn't see it before.
I will be out of town till Tuesday, so may not get the log till then, but I'll try to at least get it set up properly before I leave. When it smelled rich, it was right when I started it cold, and I only ran it for like 10 seconds... Probably just startup and surge that made it like that.... I had shut it off almost right away till I could verify that it was supposed to do that. Thanks.
Last edited by oldpartsnrust; 06-22-2023 at 08:28 PM.
Alright really nice job on the log! That kind of thorough data that makes this a lot easier.
Do another with this tune applied. Grab even more cells. Drive it longer duration and run it up a little more in the RPMs.
See if you can get cylinder air mass and knock into there, too.
Remove mass airflow.
Just a reminder, clear LTFT's and fuel trims with Vehicle Controls & Special Functions before logging.
Last edited by SiriusC1024; 06-23-2023 at 08:25 AM.
This time it'll have to wait till I get back on Tuesday. I'll post it here when I can collect it. Thanks!
That's ok no rush.
Ok, so what was done in the first tune that caused fhe surging fill the feedback from closed loop started? Was that disabling a ecm datapoint or something to get a clean deading on something else?
Running SD mode and disabling the MAF. SD fueling tables were off. That's what we're adjusting. Idle should clear up as they accurize.
Ah, ok. Without the MAF it does the surging.
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