87GMC

Well recently starting getting misfire but not all the time. When the truck is cold it never gets misfire the only time is when lets say I was driving the truck, turned off the ignition for about 10 minutes then start it again. It idles good for about two minutes then it starts missing bad and i can hear pinging but if i go to 100% it stops and then the truck runs fine. Also if i let it idle for bit while misfiring it will clear out and idle just fine.

One of the times it did throw a p0306 code but not anymore only the p0300 code. Is it possible coiling going bad? or something with injector.

I did a full flash upgrade from a 99 to 01 O.S.

Chris81

iTrader: (1)

Chris, check your O2's.. i've had similar problems before and it was an O2 seeing normal to zero voltage randomly showing misfires.. i'm tuning a guy's car right now that has the same problem.. he replaced the 02's yesterday and all is good as far as I know..

If one goes dead or cuts in and out your trims will go waaay lean on that bank causing the car to dump fuel on that side and it will buck and jerk and idle crazy.

or, I could be completely wrong.. lol

87GMC

Hey chris I think your right because it does start till computer goes into close loop. I was watching the o2 on that side and when in open loop it showing 1.107 and not moving, it doesnt start climbing down till it goes into close loop and fuel trims go way negative. I'm thinking something is wrong with that o2 or its dying. They only have a 100,000 miles on them I'm going to go ahead and buy two new ones today.

So hows the tuning going chris? Check your pm's

Chris81

iTrader: (1)

Everything is going great so far, EFIlive is the ****..

87GMC