Intermitten misfire #5 cylinder

Reply Subscribe

Thread Tools

Search this Thread

Oct 25, 2017 | 12:49 PM

br549unknown

Thread Starter

Junior Member

Joined: Oct 2017

Posts: 2

Likes: 0

Intermitten misfire #5 cylinder

I have a 2011 GMC Sierra 2500HD SLE with a 6.0 gas engine that has a part time misfire on cyl 5.( I forget what the code it gives is...maybe p0305.)
I have changed plugs, plug wires, coil, injector and still has this problem. Any thoughts on what to do next??

Oct 25, 2017 | 01:40 PM

Mike

Retired

Certified Car Nut

Joined: Jul 2003

Posts: 17,960

Likes: 1,839

From: Dark Side, AZ

Do a compression check on all cylinders.

How is your coolant?

Oct 25, 2017 | 03:29 PM

br549unknown

Thread Starter

Junior Member

Joined: Oct 2017

Posts: 2

Likes: 0

Coolant was recently drained flushed and replaced with no problems detected. System is still full.
Haven't done compression check yet. No oil loss between oil changes has been seen.

Oct 25, 2017 | 09:58 PM

Tech II

Senior Member

True Car Nut

Joined: Feb 2014

Posts: 2,878

Likes: 1,097

From: Worcester, Ma.

Agree with Mike on checking compression......if spark output was checked, and a new injector was used, a possibility is a leak at the intake gasket....

Oct 28, 2017 | 11:51 AM

CathedralCub

Senior Member

True Car Nut

Joined: Feb 2015

Posts: 6,826

Likes: 1,008

From: Earth

CathedralCub is a splendid one to behold

Agree with Tech II on possibility of intake leak and Mike on checking compression. Does it misfire at idle or while driving or both? If it misfires only at idle does the misfire go away if it idles for ten minutes? If yes to this last one then higher likelihood of intake leak.