Chevy Silverado and GMC Sierra Forum banner

6 liter misfire!

46K views 5 replies 4 participants last post by  Greaser007 
#1 ·
my 2004 Chevy 2500hd 6.0l vortec recently put out a random misfire code.... so i was told by a buddy of mine to try plugs and wires first, so i did replacing them with brand new Bosch plugs and a Bosch wires, that worked for all of a day then a very slight misfire came back, along with the blinking engine light, the code again was the Po300 random misfire code, i was told i can try new coil packs next or new injectors both i guess are famous for causing misfire problems with these motors.....? just wanna get some other input on this problem maybe someone else had this issue?

Thanks
 
#3 ·
you need to get a crank relearn done with someone who has either a gm tech2 scanner or something similar, my truck also 04 2500hd(gmc) was having this problem i tried plugs wires and a few other things and nothing worked, after the re learn i havent had a problem or engine light yet, the guy i had do it was alomst trying to talk me out of it saying it wont work but it really does
 
#5 ·
I had the exact same issue... had the crank relearn done ($25 and 5 minutes of time :) ), and she's running smooth now!
 
#6 ·
I just spoke with my local mechanic about a re-learn for my '07 6.0L engine because I have been encountering a intermittent misfire when pulling a hill under load.

Just this morning, I watched a couple of YouTube videos that showed how to clean suspicious injectors.

I think I will have my local mech do a 'diagnostic' and see what he suggests, since the problem could be as simple as low-voltage in the injector circuit.

i'll report-back in a couple of weeks to let everyone know what we find out.

If I may, I would like to share the back-fire / miss-fire Issue I encountered this spring while working on my '77 Ferd 300-inline-six with such a bad miss-fire it would backfire Both out the intake and the exhaust !
First-off - the pickup had been sitting for 3-years. I rebuilt the Holley universal 600 and disassembled and reassembled several times and purchased a new carb to single out the old carb. (no-change)
At that point I took the pickup to a local auto-electric shop, and the problem was the remote Voltage Regulator, not supplying a full 12-volts to the coil.
Duh ........... over the years I had forgotten that the remote Voltage Regulators had "points", and my pickup spent 6-years on the Pacific Coast prior to moving back to an arid climate.
The problem was Corrosion in the points contacts from the salt air.
Bingo !

So, for any of you old-farts like me, still running old-iron, check those points on occasion.

Leonard ( Greaser007 )
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top