Ok, here is the problem, I have a C5 and last wednesday, i changed my IAC (bought brand new from Honda) because i was having some crazy idle problem. When i first try to start my car first thing in the morning, i would start it, and if i dun rev my car up, my car will just stall...then i would drive it, for the first bit, everytime i come to a stop, it just sound like my car isn't even started.(idle around like 500??..then after a while, my idle will go up to like 2g........so my mechanics say it was the IAC, so we put a new one in...at first it work fine....until friday i drove it up the the highway......now the exact same prob came back up.....wat da FXXX....i just spend 3 bills on the new IAC....and it didn' last 3 days? anyone know wat my prob is?????? i don't want to spend another 3 bills.....or should honda have some sort of frigging warrnty on it? thx!!!

 

could be a vacuum leak

 

how can i check it?

 

it's most likely a vacuum leak. I had the similar prob w/ my old motor.

It ended up being a leak thru the IM gasket. Replaced it and idle stabilized.

 

hey. are you the one with civic with the R motor? at cayuga yesterday?

i had almost the same problem.. and. i just cleaned my IAC and got the car tuned . and it's little better now. . my car still surges a little but

 

yea that was me, u r?

 

i had the white itr..at cayaga..

hey man.. i was just thinking about it again..
make sure the connector to IAC and KNOCK sensor is not switched around.
mine had exact same symtom as yours and.. it ended up being those two connectors switched around

 

ya, sounds like vacuum leak. just start the car and spray all your intake side with brake cleaner, when the engine stumbles, thats your area of leak. This may be irrelevent to the c5 motors but I know my b16 has a thermol valve on the bottom of the throttle body. thermol valve causes a lot of idle problems when warm, I'm not sure if c5's have them though.

 

I have the same idle problem. If I do not turn on the air conditioning it idles fine but when engine is cold and turn on the air conditioning it would die on me.

Mechanic says it's the Idle Control Valve. Do keep us posted if you fixed your problem.

 

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