Skip at idle

**Matt Smith** · 03-08-2014, 09:16 AM

My LQ4 silverado is skipping at idle. I just changed the head gaskets and everything seems to be in order as far as installation, compression, and sealing. It only does it at idle; once the throttle is pressed it ceases. MAF sensor maybe?

**jb3golf** · 03-08-2014, 10:31 AM

Originally Posted by Matt Smith

My LQ4 silverado is skipping at idle. I just changed the head gaskets and everything seems to be in order as far as installation, compression, and sealing. It only does it at idle; once the throttle is pressed it ceases. MAF sensor maybe?

I would re-check all your lines, and make sure everything is tight. ..If you weren't having issues with the idle before your install..then go over the small details...good luck..

**Matt Smith** · 03-08-2014, 11:18 AM

Thanks for the guidance. I also meant to bring up that it's burning very rich at idle. I also unplugged the MAF sensor at idle at it began to idle fine.

**cammed goat** · 03-09-2014, 07:24 AM

Clean the MAF with C&C MAF cleaner and see if it works. If not, your MAF is probably on its way out. Has the MAF ever been cleaned? How many miles on your rig?

**Matt Smith** · 03-09-2014, 08:00 AM

156,000. It finally threw an active fault and CEL after I cleaned the MAF. it doesn't skip anymore but it idles high and it stumbles when the throttle is pressed.

**cammed goat** · 03-09-2014, 08:44 AM

Might have to clean your IAC valve next to get that idle issue sorted.

**Matt Smith** · 03-09-2014, 11:59 AM

I cleaned the MAF sensor. Didn't work so I got a new one. And it still idles weird. I'm looking at it being the IAC. I'm gonna clean that then see. When I go to work tomorrow I'll be able to test it. I don't have a VOM in my toolbox here.

**35th-ANV-SS** · 03-09-2014, 01:15 PM

Yea, replacing parts on a hunch is a bad idea.

Have you checked for vacuum leaks? Running rich and poor idle both can be contributed to a vacuum leak.

**cammed goat** · 03-09-2014, 02:29 PM

I agree with Jon. With these vehicles, clean MAF, throttle body and IAC as well as check for vacuum leaks. From what I have seen in person as well as on the forums, changing the MAF is a 50/50 chance fix. Sometimes the replacement works, sometimes it doesn't.

**pajeff02** · 03-09-2014, 05:52 PM

Can you be more specific -- "idles weird" means what?

**Matt Smith** · 03-10-2014, 12:26 PM

I was able to find the cause. After I tested the IAC I decided to try some ether just to check if the intake wasn't sealed. And the EGR was the cause. It had a slight vacuum leak. So I fabed a cover for it and the headers. Fixed the idle issue.