Idle hanging up/ tuning problems.

**Red Z28** · 10-19-2011, 08:11 AM

Got my car tuned runs good but when i push in the clutch or put it into neutral the car jumps up in rpm and slowly comes down. When I'm not moving i don't have this problem it's only when I'm moving. He opened the throttle blade and i think that could be messing with the IAC valve. Any ideas?

***SMWS6TA*** · 10-19-2011, 11:34 AM

when you say jumps up how much? a couple hundred in rpm? - no issue that's normal. Now if it jumps up 500rpm or more then that is an issue.

You can take the IAC out and clean up the carbon/oil build up. It may help.

If he had open the blade to much you would have a constant high idle.

**PFM** · 10-19-2011, 11:51 AM

Stock TB?

**My00Z28** · 10-19-2011, 01:03 PM

this reminds me of my problem i was getting to much air past the throttle blade in my ported throttle body when i would stop the idle would drop to normal but when moving it would idle at 1500rpm you may need to adjust your throttle blade closed more if that is the problem!

**Cutlass** · 10-19-2011, 06:10 PM

op, list all your mods, too

**Red Z28** · 10-20-2011, 08:55 AM

I have a 80mm BBK throttle body, gm hot cam, ls6 springs, hardened rods, 1.7 to 1 roller rockers, slp airbox lid, k&n air filter, mass air screen removed, bbk intake manifold, cat delete, egr & air delete. Idle jumps up to around 2000rpm when moving, they cleaned the IAC not it idles rough at cold start.

**Cutlass** · 10-20-2011, 05:52 PM

I've heard that BBK tb can be problematic. Same goes for there Intake manifold. People have had issues getting then to seal up nicely. Double check the intake for a vacuum leak.

The TB should be set up so that at idle the throttle position sensor voltage is around .4 to .6 volts. Hopefully when its adjusted to that voltage, the blade is closed enough to allow the IAC to control the idle speed and idle airflow. the IAC counts should be at least 40 at idle. A little more is ok but 40 gives the IAC a good cushion up and down to control the idle speed.
If you can't get the car to idle at TPS voltage .4 to .6 and IAC counts way high, then you can open up(or drill) the hole in the throttle blade to allow more airflow to bypass the blade. That should help bring the IAC counts down.

**0rion** · 10-20-2011, 07:02 PM

with a hotcam and those mods there's no reason you shouldn't be able to get that to idle without drilling the blade. Who did the tuning and how experienced were they? I run a 228R and didn't have to drill my blade. It sounds to me like your idle airflow tables need worked over but first you should rule out anything mechanical like cutlass said.

**RedHot99T/A** · 10-28-2011, 01:30 PM

Im haveing the same problem too,diff mods but same problem...hmm and mine started after being tuned also...dont mean to hijack your thread...but im gunna go back and hes gunna check it out ill let you know how it turns out man.

**DaddySS** · 10-28-2011, 07:04 PM

Originally Posted by 0rion

with a hotcam and those mods there's no reason you shouldn't be able to get that to idle without drilling the blade. Who did the tuning and how experienced were they? I run a 228R and didn't have to drill my blade. It sounds to me like your idle airflow tables need worked over but first you should rule out anything mechanical like cutlass said.

Agree, sounds like a tuner problem. Take it to a different tuner.