LS376/495 High Idle

[WRC7732]

Hi All,

New here, as I'm sure you can tell from the post count.

I've been looking around (and searching) but haven't had any luck finding a definitive answer.

I put an LS376/496 GMPP crate engine with the matching E67 PCM in my 96 Corvette with a ZF 6-Speed that was in the car.

I've had the car tuned by a shop about and hour or so away from me.

The car runs great except for some light stumbling here and there, and the occasional spit (3 times in 4,000 miles).

I'm running a speed density tune because I was having really bad stumbling determined to be MAF turbulence (stock LS7 filter housing with 8" long 4" tube to the TB, so not sure why).

The reason for my post is that I recently purchased a HP Tuner MPVI Pro to learn how to tweak things to get it as good as I can, and so I can do it myself on the next one.

- Job one is that I want to drop the idle speed. It currently sits around 900, and is quite smooth. But I'd really like to have in down in the 700's or so, and hopefully pick up a little lope from the cam while I'm at it. Problem is that adjusting the Target Idle Speed doesn't do it. It was already set at 800, and lowering more didn't make any difference. Also, while in the Scanner program, I was not able to 'Command Idle' below 900 either. The number I could change, and it would rise and fall with the command, but would not go below 900 on the way down no matter what I set the number to.

Any guidance on next steps would be greatly appreciated. I'm sure you all would like to see what I'm running so I'll attempt to post my tune here for your perusal.

Thanks in advance for any help provided.

Will

[5FDP]

What's timing like at idle? Maybe lowing timing some could bring the idle down if it's too high.

Do you have a log?

MAF issue could have been maybe not having a MAF screen if it was a card style MAF, just a guess there.

[WRC7732]

I think I attached the tune config as it sits currently to the original post. I want to say that base idle timing is around 14. But I'm not at my computer and my phone won't pull up the file. I haven't figured out how to data log yet. Tips welcome.

Thanks.

What's timing like at idle? Maybe lowing timing some could bring the idle down if it's too high.

Do you have a log?

MAF issue could have been maybe not having a MAF screen if it was a card style MAF, just a guess there.

[WRC7732]

What's timing like at idle? Maybe lowing timing some could bring the idle down if it's too high.

Do you have a log?

MAF issue could have been maybe not having a MAF screen if it was a card style MAF, just a guess there.

I think I've managed to save a log, and hopefully attach it.

Thanks,
Will

[WRC7732]

No one have any ideas?

[SSUte01]

I caveat this with I've never used a GMPP OS, however I seem to recall reading a fair while ago now on here that their OS had some sort of issue with target idle not matching actual idle. I cannot recall the resolution, or even if there was one, but I do believe you're not the first to have actual idle above targeted idle with GMPP OS.