Adaptive idle doesn't take over
 

I've got a 2002 Corvette with a new 454ci LS, a P59, and a Katech 102mm throttle body.After startup, I can hold it at 1500 or 2000 RPM and it runs smoothly. But as I ease off the gas pedal, the logger shows the throttle continuing to close, even as the engine speed drops below the desired RPM, and the MAF drops below the desired g/s. And then the engine just dies when the throttle closes too far and the MAF drops too far. It seems like the idle control feature just refuses to take control of the throttle.

Any idea what I should look at to try to fix that?

Relevant changes so far:
Cylinder size is updated to match the engine.
Injector scaling is from Injector Dynamics.
MAF scaling is the same as my previous setup since it's the same sensor and intake pipe.
Throttle body scaler is 0.012238
Desired airflow for idle is 22 g/s at operating temp, ramping up to mid-40s at ambient temp
^ The airflow is kinda high but I also raised my target idle speed, and will lower both as soon as I can start tuning the usual idle tables.
Sparking timing is 22 degrees,in the idle range, with correction tables that go to +7 and -3.
I tried setting the max-RPM for speed-density to 400 RPM to ensure that the car runs on the MAF sensor alone, and that didn't make any difference.
AFR is not perfect but is close enough for now - it enters closed loop and works fine when I hold the RPM from 1000-2000 with my foot. I'll get that dialed in properly that after I get it idling properly.

Thanks in advance for any suggestions!

Post your tune.

if you have an aftermarket throttle body you may need to adjust the idle screw. I like to get it up to temp then use the throttle blade adjustment to get iac counts to 2-20ish. You usually need a few warm up cycle to get the physical adjustment to properly align with desired airflow so you have the best cold and warm starting/idling
the last car i tuned had a super loud iac which was really annoying so I favored minimizing the iac opening everywhere I could.

when changing tb the iac area table may need to be adjusted.

log your iac counts to help you get those tables dialed in.

a C5 is drive by wire

2002 also use p01 stock not p59. But if it’s indeed dbw then none of what I said applies.

Yes, it's DBW, and yes, I swapped in a P59. Sorry for the confusion.

The tune is attached, and the corresponding xdf, since I'm using TunerPro.
I had to append ".xml" to the xdf file, since ls1tech doesn't allow uploads of .xdf files.

Thanks again for any help!

What are your idle airflow trims showing right before this happens? Log those in addition to the cracker airflow, etc to troubleshoot further...
Too bad the file is not in HP Tuners format, makes it hard to compare against all of the stock files I have here for reference. Only thing I use tunerpro for is creating XDFs.

i happened to have a p59 on the bench so i flashed it and read it back out with hpt.

OK that helps, but NSFW what is the original model/year vehicle OS that you used? The VIN is showing an 03 hummer, is that the real donor OS? If it is I would switch it out to a 2004 C5 for starters...

Also why the switch to the P59? For a naturally aspirated deal I wouldn't even bother as you will have little quirks here and there, the big benefit of the P59 is the ability to use flex fuel with a 3 bar OS.

Some context:

I switched to a P59 because I hope to modify the software to add some new features. I don't want to derail this thread with the details, but I'll start a new one if I make some progress. There is no room for new code in the P01 but the P59 has twice as much memory and most of it is unused. I also have some extra info that gave me a head start in reverse engineering the 7603 OS that was used with the P59 in the 04 Corvette.

The car will be getting dyno tuned when the tuner gets back in town in about a week, and I'm hoping to get the start/idle/drive stuff sorted out before then. I did a fair amount of start/idle/drive tuning on my previous engine so I figured I could save us both some time and trouble this way.

I sent him an 04 Corvette bin file with a few changes, he made some more changes, and I flashed the file that I got back. Or that's what I thought... The Hummer VIN might indicate that he sent back was (based on) one that he used with a previous customer. I'll ask.

And now I gotta double check the other changes that I made to my own base tune to make sure they're still in there.

If the 03 Hummer is DBC then that could explain the whole problem.

Thanks for pointing out the VIN, that's a game changer.

Have you messed with boostos? I’ve been beta testing v5.
what features are you wanting to add?
pcm hammer has been a game changer for me

I'm staying NA, so no boost for me. I kinda want paddle shifters though, and the first step in that direction will be rev-matched down shifts.

Is it supposed to be an auto or manual tune?

It's a manual car, should have a manual tune. I'm at work right now so I can't check the tune but if I remember right it only has valid MAF values in the drive column, and zero in the PN column (or vice versa). If it's configured to be an auto tune and there's no switch in the transmission then that's probably it. Or even if it's an M6 tune and the neutral switch works differently on the 04 year vs 02 year.

Those columns full of zero were right there in front of me the whole time and I never thought to copy the 'real' values into them. Facepalm.

Also, while I didn't check the VIN in the bin file character-by-character last night, it looks about right for a Corvette.

hpt listed it as a 2003 hummer h2.

im pretty sure pcmhammer wrote the vin from your bin to the pcm. i selected "write os calibration and boot" when i wrote it.

looks like the vin thing was my mistake. i rewrote it as full clone and read it back out again

Cool, that explains the VIN thing. :)

The tune is set to manual. I copied the desired-airflow values from the in-gear column to the park-neutral column (which was previously all zero) and I'll test this tonight.

I'm guessing the neutral switch either works differently for 04, or got damaged sometime between now and the last time I drove it. Fingers crossed...

What's the IAC passage like on this TB? I'm guessing there is no hole in the TB?

d b w

try this