Hey,

I have a slight problem and was wondering if anyone has had the same problem or knows what it is.

When I turn the air conditioning on in my car the idle is smooth as normal, but when sitting at a light about every 5-10 seconds the idle drops by about 100-200 rpm from normal and it slightly jars the car. It is only noticible when the car is idleling and it has never happened when the air conditioning was not on.

Thanks for the help.

 

When the compressor kicks in, it puts a load on the engine, hence the idle drop. The ECU then compensates and bumps it back up. When the compressor kicks off, the opposite happens. This is normal.

 

Try cleaning your throttle body, it won't hurt to give it a shot.

 

I actually just cleaned my throtle body about 3 months ago.

Up until about a month ago I never notice the roughness of the idle with the air conditioning on which so it seems like something might be different now.

 

I have the same problem as you. I tried some fuel injection cleaner and high ocatane gas, but it still comes and goes. It's getting annoying.

iwannabmw,

He's not talking about the compressor turning on. He said that while he's idling with the A/C on, he feels irratic jarrs every 5-10 seconds.

I still haven't figured out the problem. We might actually need to clean our IACV (Idle Air Control Valve).

 

ive had the same problem....but little different....few months back, i would get a little rough idle like once a month....now its become a little more common....if i have my a/c on itll be fine, then when i turn it off itll drop to around 500, and a little lower if i drop it into reverse.....i think the IAC valve is definately in need of some cleaning

 

Ooops, I guess I misunderstood the post.

 

Where is the IACV and how do I clean it?

 

it might have something to do with your compressor clutch pulley. It could be going bad. Do you have problems when the ac is off? If things get real bad, you could take your ac belt off and leave the ac off to see if that helps. That could help you troubleshoot your problem.

 

There is no problem when the air conditioning is off.

 

When AC on, the engine felt hard to accelerate (even for light accelerate to make it move from stop light)..have to press pedal deeper compared with AC off. Is there any vacuum leak in my system or what? thanks

 

you probably have a misfire which means one cylinder is not working, turning on the A/C and it's associated load makes it feel even worse

 

sorry out of the topic, but i think you`re right because i smell gas rich exhaust and my engine is vibrate quite excessive (by observation and the i can fell it in the steering wheel). Have change the coilpack but the problem not solved yet...will check the fuel injectors later

 

THere isnt only jus the IACV...there is another valve for the idle with the A/C on. Its located where the IACV is. Its one of the other electrical connectors there. There are 3 or 4 connectors there depending on the year.