C6 Random misfire at idle without Ck Engine Light

Reply Subscribe

Thread Tools

Search this Thread

Nov 6, 2013 | 05:36 PM

lucky17

Thread Starter

4th Gear

Joined: Nov 2013

Posts: 4

Likes: 0

C6 Random misfire at idle without Ck Engine Light

Car runs rough at idle, dealer indicates random misfires (different cylinders each time they start the car). Check engine light has not come on. Dealer has performed series of diagnostics -- nothing. Cleaned injectors. Cannot find any vacumn leaks. They say fuel presure seems okay. It does not misfire with load only idle. Any ideas?

Last edited by lucky17; Nov 6, 2013 at 05:38 PM. Reason: spelling

Nov 6, 2013 | 07:00 PM

truckplay

Melting Slicks

Joined: Oct 2010

Posts: 2,220

Likes: 16

From: Sugarhill Ga

what engine ? has the car had any work ? did you check fuel pressure ? compression ? check the harness to the injectors and coils make sure they are all snapped in. check all wires to see if they are on all the way.
you may want to slide the cam sensor out, check the connectors, and check for oily residue or damage. if you see damage you may have a timing gear getting loose.

Nov 6, 2013 | 07:33 PM

lucky17

Thread Starter

4th Gear

Joined: Nov 2013

Posts: 4

Likes: 0

thanks - engine; LS3 6.2 liter. Car has 17k miles, no accidents no mods. Just purchased it and believe it is all stock. just put plug and wires on in an attempt to see if thiat was an issue (actually put 2 sets just to make sure that was eliminated as the source of the problem). Dealer said they checked fuel pressure and compression. They also cleaned injectors just to see if that helped ... to no avail. The part the has the dealer puzzeled is there are no codes being generated to help identify the source.

Nov 6, 2013 | 07:38 PM

lucky17

Thread Starter

4th Gear

Joined: Nov 2013

Posts: 4

Likes: 0

even the check engine light has not come on ... not even a flicker

Nov 7, 2013 | 04:52 PM

Chevy Cust Svc

Race Director

Joined: Mar 2010

Posts: 16,014

Likes: 829

Hey Lucky,

Have you spoken to Customer Care? I would like to get this all documented for you in our system. This way if something does come up we have a frame of reference when it all started.

Please PM me with your VIN, mileage, address, phone number, name and the name of your dealer.

Thanks,

Kelly J.
Chevrolet Customer Care

Nov 7, 2013 | 08:12 PM

billet racing

Instructor

Joined: Aug 2011

Posts: 133

Likes: 2

mis fire

Are you sure it's a misfire, or just the rumble of the engine. My wife seems to think it skips a beat at idle, but to me its just the rumble of an engine and a low idle, Gets down to 500+/- rpm's. I'm used to the muscle cars with a big cam, so it seems natural to me. Actually enjoy it.

Jerry

Nov 7, 2013 | 09:08 PM

lucky17

Thread Starter

4th Gear

Joined: Nov 2013

Posts: 4

Likes: 0

thanks for the feedback -- it is certainly a misfire. I've had two separate shops perform diagnostics and both have identified misfiring at idle. Neither knew what the other had performed and I didn't suggest anything to influence their review, actions or conclusions. Both shops concluded the same thing and both shops are perplexed on why (source of the problem).

Nov 7, 2013 | 10:17 PM

exracer28

Drifting

Joined: Jan 2002

Posts: 1,576

Likes: 85

From: Sumter SC

I had this problem with a new ls3 and got nothing but run around from local dealer. I ended up fixing a brand new car on my own nickel but it was that or sell it. Dealer said unless the check engine light came on there was nothing wrong and this was after I showed him the tech2 misfire data. Sad that dealers are so poor. I sent injectors out and I had two replaced and now car runs as it should. The experts here said that it is a performance car and should have a rough idle. If you can remove the injectors and have them flow checked it will show up any issues. I spent a few extra dollars to get a balanced set.

Good luck.