Low Idle Possible Causes

Subject: Low Idle Possible Causes Fri Sep 25, 2015 2:53 pm

What are the possible causes of a low idle? In park it idles at about 650 and in drive it idles at about 550, sometimes lower. The idle is a little rough in park and not as rough in drive. This has started over the last week or so that I've owned it. I've been driving it quite a bit. Other than that, it drives great and feels really smooth.

It could be plugs and wires (needs that done) or maybe something is up with the IAC valve. Do you guys have any other suggestions?

Subject: Re: Low Idle Possible Causes Fri Sep 25, 2015 7:20 pm

It could be your PCV valve.

Subject: Re: Low Idle Possible Causes Fri Sep 25, 2015 7:23 pm

I changed that already.

Subject: Re: Low Idle Possible Causes Fri Sep 25, 2015 7:37 pm

You did not tell us that.

Subject: Re: Low Idle Possible Causes Fri Sep 25, 2015 7:43 pm

It started about 4 days ago. So far I've cleaned the throttle body (without removing), changed the Pcv, and replaced the MAF. Also I keep getting a P1040 code about the air pump. Somebody half disabled it. They only pulled the relay. I put it back, plugged the hose to the air box and disconnected the power to the pump in an attempt to trick the computer.

Subject: Re: Low Idle Possible Causes Fri Sep 25, 2015 7:53 pm

I remember reading about this on ISSF.

Subject: Re: Low Idle Possible Causes Sun Sep 27, 2015 11:28 pm

LT1 car I'm assuming....

-Vacuum leak?
-Cattywhompas EGR?

Posts : 5848 Join date : 2008-12-28 Age : 114

Mattb wrote:: What are the possible causes of a low idle? In park it idles at about 650 and in drive it idles at about 550, sometimes lower. The idle is a little rough in park and not as rough in drive. This has started over the last week or so that I've owned it. I've been driving it quite a bit. Other than that, it drives great and feels really smooth.

It could be plugs and wires (needs that done) or maybe something is up with the IAC valve. Do you guys have any other suggestions?

I,ve noticed with your threads asking for idea's,..

you usually know all the answers,. because as the possibilities get discussed., you have either "done" that,. or you offer some other information,..

Most people quickly become google educated on their particular problem,..

Subject: Re: Low Idle Possible Causes Mon Sep 28, 2015 7:26 pm

Yeah you're right. I searched on the impala forum and found the information I was looking for.

Subject: Re: Low Idle Possible Causes Wed Sep 30, 2015 3:34 pm

I haven't totally solved it yet. I just changed the fuel filter, which was really filthy inside, and that improved the idle a little.

I think it's just a combo of a bunch of little things. So far I've addressed most of the typical "tune up" stuff with the exception of plugs and wires.