low, rough, surging rpm at idle after hot start

**wcidioti** · 05-10-2009, 06:20 AM

hello,
having a caprice/statesman 2004 ls1. problem is when starting car while it is still hot from the previous start, the rpm reading goes as follows. starts at 1000, then a few seconds decreases beyond the normal 700-800 to nearly 500, at that point the engine shivers, and if you press on the gas while in drive it will not produce power to move the car.. i would wait for a minute and the rpm would suddenly jump up from 500 up and down quickly a few times, stabilising at the normal 700-800.. then i can drive normally. other than that it is very good in all aspects..

**Frost** · 05-10-2009, 06:25 AM

The IAT sensor is in a bad spot and is getting heat soaked when the car sits for a short period and is restarted (like stopping at a gas station). With it reading falsely hot, your mixture is lean, that's why the engine is weak.

What platform are you using to tune with?

**wcidioti** · 05-10-2009, 12:10 PM

aha, makes much sense..
anyway, i forgot to mention that while this happens the engine check sign would come on.. but that is just a consequence.. where is the iat sensor located ?
the ls platform

**Frost** · 05-10-2009, 10:32 PM

I mean what tuning platform as in which tuning suite.... this is the TUNING section

The SES should not be coming on though. Without the scanner in a tuning package, our ability to trouble shoot is greatly hampered.

**wcidioti** · 05-11-2009, 11:01 PM

i dont know info about the platform or tuning.. as i havent come accross that..
anyway, while this low rpm shivering happened earlier i poured water over the stem of the intake (maf, iat) after which the engine self corrected (rpm). i will probably add insulation instead of relocating.
thank you,