03 denali 6.0 need help!!

[deucebig86]

i have an 03 denali with the vortec 6000 i have not owned it very long. it has alot of miles (190k) but every now and then usually when it is cool out or the sun is not up yet when i start it, it will spit and sputter and lope horrible. engine light will come on and flash if you drive it like this but if you warm the motor up and stop and restart it it runs fine and engine light goesoff. the computer says engine misfire on cyl 1 and 3. i had to replace a fuel injector on number 1 due to a constant miss but that didn't cure this. the thing i dont understand is why it just does it every now and then. a mechanic SAID it has low compression on the number 1 and 3 cyl (80lbs) but it runs fine and has plenty of oil psi and power? any ideas please? i really like this vehicle but mechanic says get rid of it?

 

[Donut Slayer]

get a new mechanic. If it only has the problem in the morning, its not mechanical its electrical. You will need to leave the vehicle overnight with a good mechanic so the problem shows up when they look at it.

 

[JennaBear]

Clean your MAF and TB, unplug battery for 15mins to reset PCM.

 

[deucebig86]

it has a new MAF and a different very good mechanic has it now but the 3 days hes had it go figure it wont screw up! he thinks its most likely a wire loose or shorting out. it says engine misfire cyl 1 and 3. hopefully we shall find out soon cause im ready to drive it and not worry about reliability!!

 

[deucebig86]

well nearly a month later we find the problem! broken valve spring on the no 1 cylinder. easy fix was just tricky to figure out. GM junk! lol