GMPP LS376-525 crate package high idle

I have searched and found quite a few threads asking for help with the same problem, but nobody posts about what fixed it...

A friend of a friend asked me to look at this tune file. He has put two of these GMPP crate packages into older hotrods. They both do the exact same thing. They idle at 950-975, and they both run and drive just fine. But he wants the idle to be closer to 750 or 800.

In the tune file, the commanded idle is 850, minimum idle is 825. I lowered the RAF tables by 20%, no change in idle. I lowered the RAF tables by 50%, no change in idle. Then I zero'd out the RAF tables, and the thing still started up and idled at 950. I smoke tested for vacuum leaks, none found. PCV system is correct. I don't get it.

Are these things hard-coded from GM? I'm using version 2.23, here's the file.

Did you let the cars run for a few minutes? There is a startup idle table and your commanded idle rpm is going to be 1000 rpm to 950 for a good minute or longer based on your table. The table needs a little work, the hot cells should all be the same as your desired idle rpm.

Log desired idle rpm and make sure it says what you want it to say.

Zeroing out the tables won't take effect right away either because there will be a learned value from the integral airflow correction. Try disabling all the adaptives and seeing if changing the base airflow has any effect.

See my guide here on how to do that.

http://www.hptuners.com/forum/showth...e-tuning-guide