Where is the IAC? My car RPM's drop when coming to a stop and almost seem to die. I had Bryan raise the RPM to almost 1000 RPM to keep it from dying but it still drops to almost 400 RPM's before picking back up. When it is not fixing to die, the high idle RPM are causing the car to surge forward as soon as I release any break pressure. I am pushing the break pedal almost as hard as I can to keep it from moving forward. Any help would be appreciated. Thanks,

Kyle

 

It is on the bottom RH side of the throttle body. There is little room to remove it without taking the throttle body off.

 

Should be on the throttle body, you have two sensors, one being the TPS the other the IAC.

http://csce.uark.edu/~jgbertr/rb/iac2.jpg

 

What should I look for to see if it is bad? How much would a new one cost? Thanks,

Kyle

 

It can get gunked up to where the pintle does not move in/out like it should and also the passages can get clogged. Clean it out and see if it helps.
A new GM one is ~$56 wholesale. Probably cheaper at Autozone, etc. You might need a new gasket for the bottom (GM p/n 17113074). Oh, you might need a throttle body mounting gasket, too.

 

Hmm...I have the hotcam and tunning from Bryan as well and my car does the same thing. If I come up to a stop sign and let off the gas and stop real quick, sometimes the idle will dip real low, and then come shooting back up. Only difference is I have a 6spd.

Aaron

 

That's exactly what mine does. the faster/harder I top the more it will drop. If I come to a gradual stop, it doesn't really do it. Is this a sign of the IAC?

Kyle

 

Could be. The IAC may be "lazy" or trying to overcome gunk in the passage. Take it apart, clean it out, put it back together and see if it fixes it.
You should also make sure you have no tears in your intake elbow. Also no vacuum leaks that could upset IAC control at idle.

 

Thanks. I have learned more of the specifics about the LT1 in the past 2 weeks reading your posts and seeing the pictures you always post. Thanks,

Kyle

 

I tell you, my car did this EXACT same thing!!

I found that the bottom of my intake elbow had slipped quite a bit. So, there's no telling how long or how much unmetered air the throttle body had been pulling in.

I got it back on nice and tight...and as simple as that, the problem was fixed for the most part. NOW, my car idles higher than normal 1500RPMs. So, while my immediate problem was fixed, I still think there's an IAC problem that I need to address.

Sadly, my boot is in such poor shape that I can't remove it again until I can buy a new one...soon, hopefully.

DJ

 

I have a functional ram air hood (similar to the WS6 style) and no longer use the intake elbow. I have 2 short pieces of rubber connectors that would not be able to be installed if it weren't on correctly. I probably wouldn't even need clamps to tighten it, it is so tight. I am going to try and clean the IAC first and go from there.

Kyle

 

Good luck man. IACs are about $50 from Advance and more from dealers; if it comes to that. Hopefully a good cleaning will open 'er up for you.

DJ

 

Hey Guys,

My car does this also when braking or if I give it some gas and then have to let off real quick it surges back up.. I would describe it as if it feels like a weighted circle that as it makes a revolution it continues on for a moment if that makes since.

Shawn