IamSam

iTrader: (2)

Hey guys. My idle shows about 1400RPM on the tach, but my scan tool shows it as about 1200RPM. I hooked a vacuum guage up to the manifold and got 18 inches of vacuum. Is this a normal reading for a stock (i think) lt1?

I took the IAC out and checked the amount of ohms between terminals A and B, then C and D. Im getting around 50 ohms for the first terminals, but Im getting OL for the second.. So I need a new IAC?

I was searching for a new IAC on the common parts places, but they are all quoting me around 130-140 bucks! I looked at the IAC from my mom's car (2005 Imapala w/ 3.8L) and they look identical. I looked up her cars IAC on the same site and the pics are the same. But the they only want $30 for the one for her car and they actually have it in stock.. they wanted to order mine. Is there really a difference, or are they charging more for the same part? Heres an example:

http://shop.advanceautoparts.com/web..._536973024___#

http://shop.advanceautoparts.com/web..._536978813___#

the_merv

iTrader: (88)

Check for Vac leaks.

Gojira94

iTrader: (4)

Here you go:




So you might indeed... I used a BWD from Advance, about $30.00 IIRC, no problems with it.

old93camaro

iTrader: (8)

Have you done anything different before the high idle like change TB, adjust screw in TB or TPS senser if so that can throw off IAC counts...

Gojira94

iTrader: (4)

Sorry, what car & year is this?

IamSam

iTrader: (2)

sorry guys i sold the car, but for future people who are searching who may have this problem:

It was the IAC valve. The IAC for the impala worked perfectly, the connecter just sat upside down but caused no issues.

klass1c

having that same issue now w/ my iac, so the 05 impala's iac really fit and worked?

IamSam

iTrader: (2)

Yes it did! And its only a fraction of the cost for one for an LT1. The connector just sits upside down, but dosent cause any issues at all.

itSSlowZ28

iTrader: (5)

awesome that the IAC works. i think i need a new one, so i'll go pick one up tomorrow

itSSlowZ28

iTrader: (5)

update: just put on the exact IAC in the link provided. my idle got even higher. its been idling at about 1500-1700 rpm's. with the new impala IAC it jumped to 2k. a quick rev and it stuck at 2300. i disconnected the battery to hopefully reset the computer and let it relearn the new IAC, but i'm doubtful that will work

LT1FirebirdSLP

iTrader: (2)

Your issue screams vacuum leak. Start off with checking hoses such as brake booster and PCV's. Once you go through all that stuff, check to see if the issue has resolved itself. If it has not, then consider intake gaskets. A blown intake gasket will cause a significant rise in idle speed but also causes the characteristic "getting stuck at high RPM" after applying throttle. The idle speed will eventually settle down after 10-20 seconds but definitely takes longer than when operating correctly. If you have replaced the IAC already I would probably just jump to checking your intake gaskets. Unfortunately, the only way I know how to check an intake gasket is to replace it, LOL!