Greg Pippin

iTrader: (3)

I've searched everywhere and haven't found anyone decribing the same exact idling problem i have. So the car starts and idles around 1000 or whatever rpm that it is set to and over the next minute or two the idle slowly increases till she ends up around 1500 rpm or more. I can put the car in drive and the rpms drop to 950 or so. Hooked scantool up and in park it shows 400 to 500 rpms more then desired idle but when u put it in drive the rpms match the desired idle. This happened before the head and cam swap and after and before the computer was tuned and now still happening after the pcm tune. I have replace new iac, new coolent temp sensor, new 58mm throttle body, new 160 stat, a couple new pcv's and rubble gromits, resealed all the holes in the intake, new optispark, new intake and intake gasket, set the tps at .67 volt ,have opened up the blades on the throttle body and reset the tps again, have reset the tps numerous times and still no luck. I can't find a vacuum leak no where. Its done this for over a year and now its an kinda a problem now with the cam.

cardo0

My TPIS TB has a high idle too. Kinda acts like a carb where is starts low and creeps up to 1000rpm. Had a good LT1 mech look at it and he said it maybe the throttle plate shaft is too tight. May loosen with wear.

Did your high idle start before or after the TB swap?

Formula313

Think maybe the cruise control cable maybe too tight..?

Greg Pippin

iTrader: (3)

Its not the cruse cable. I'm still at a loss with this

BALLSS

what are your IAC counts when the idle is high?

or jump to the end and put the stock TB on to see if it resolves the idle issue....if idle is good then address what you need to do to "mod" the 58....or sell it.

Greg Pippin

iTrader: (3)

It was a issue before the mods. Its just more of a issue now. It was doing it with the stock everything

FbodyNation

Engine light on? Any codes stored?

BALLSS

Have you scanned to see what the IAC counts are?

redhot lt-1

iTrader: (2)

check your codes you may have a bad mass air flow sensor or TPS.

hrcslam

This. What are the IAC counts? Also, compare MAP kPa between High idle in neutral and low idle in gear. Also note IAC counts in each position.

What are the IAC counts at normal idle vs high idle in neutral?

If they are the same, or lower at high idle, it's most likely a vacuum leak.

If the IAC counts don't change at all between neutral and gear then it's either a bad IAC valve or something related to it's control (tune).

If the IAC counts go up with idle speed then it's causing the idle problem. If that's the case, whats the TPS%?