A couple of weeks ago my 2004 GMC 2500hd started misfireing while driving. I took it to a GMC service center & they don't know whats going on with it. They have never seen this type of issue. It produces no service engine light nor codes. They reset the computer & after about 30 seconds it starts all over again, misfireing in order. they checked all of the sensors, fuel pump etc. no problems noted. Any ideas??
Misfireing on all 8 cylinders with no codes, or service engine light?? on 2004 GMC Sierra 2500 HD
by Visitor in Phoenix, AZ on May 10, 2010
ANSWER by Visitor on January 11, 2011
I don't have a answer I have the same problem. My fuel pressure is about 45 to 48 psi. A mechanic said it should be around 60 psi. all the time. I don't know anything else. I hope I/we can fiqure this out.
ANSWER by Patriot123 on June 13, 2013
I have a 2006 2500HD and it is doing the same thing, did you ever find out what causes this? Had it to two different shops, no codes, replaced everything but still have this sporadic issue.
The truck has 88kmi.At 60-70 mph I get a p0300 code.The misfires are listed as cyl 1 and cyl 6.Here is a list of things I have tried with little or no change:new plugs/new wires/8 new injectors/new...