Number 8 cylinder oil on the spark plug
05-07-2009, 08:48 PM
#1
Number 8 cylinder oil on the spark plug Slowly over time the number 8 plug gets enough oil burnt on it to cause idle problems. I didn't have it checked but i'm sure its a valve seal or guide problem. Its been doing this for a very long time. Using the gm iridium plugs really helped to stop it from fouling completely.
Is there a little hotter plug i could put in number 8 cylinder or better plug to use in oil. It doesn't foul the tip but slowly over time it crusts up the threaded area and starts to build up until it partially fouls the plug. PCM doesn't see it as a missfire but it hurts the drivability.
I know gm went to these irduim plugs to try and solve the poor idle because of the oil getting on the plugs.
Is there a little hotter plug i could put in number 8 cylinder or better plug to use in oil. It doesn't foul the tip but slowly over time it crusts up the threaded area and starts to build up until it partially fouls the plug. PCM doesn't see it as a missfire but it hurts the drivability.
I know gm went to these irduim plugs to try and solve the poor idle because of the oil getting on the plugs.
05-07-2009, 08:53 PM
#2
Ive had this exact problem for a while too, #7 and #8 both do it. But its worse on 8. Every once in a while Ill pull both and either replace them or clean them with brake cleaner. I figured it was because of the oil that tends to accumulate in the intake. And it gets sucked towards the back of the intake. I installed a catch can recently and that seemed to slow the buildup some. Also I park in a steep driveway, so maybe thats contributing as well. I use NGK TR55s, but I never noticed anything weird when it had the stock plugs in it.
05-07-2009, 09:46 PM
#3
Number 7 is clean and i have very little blowby but i do have a slight tick. I'm guessing the valve guide possibly. I may try a NGK TR5IX in the number 8 cylinder. I also thought about running the plug at .038 instead of .040. Thanks for the input,good to see what others have experienced.
05-09-2009, 09:15 PM
#4
Well, I replaced plug on #8 and cleaned the plug on #7 a few days ago.
It ran fine since then but just a while I ago, I was sitting at a light and it started misfiring and hesitating on acceleration. It did it for a few minutes then went away while I was driving home. I am suspecting the ignition coils may be going bad. Maybe with them being tucked way back there, the heat gets to them.
The whole time it misfires it never sets of the SES light, which is odd.
It ran fine since then but just a while I ago, I was sitting at a light and it started misfiring and hesitating on acceleration. It did it for a few minutes then went away while I was driving home. I am suspecting the ignition coils may be going bad. Maybe with them being tucked way back there, the heat gets to them.
The whole time it misfires it never sets of the SES light, which is odd.
05-10-2009, 06:06 AM
#5
Mine does the same thing, Sit at a light and it will start to miss a little. I seriously doubt your coils are weak etc, try less gap on those two spark plugs.
I'm battling a new problem now, If i sit at a light for 30 seconds then pull away the car runs great for about 1/4 mile then starts to loose power. Fuel pump is ok and checked a bunch of other things and i can't figure it out. I guess i need to get a good scanner and see if its pulling timing. I wonder if when you idle at a light the PCM goes back to open loop then as you pull away it goes back into closed loop?
I'm battling a new problem now, If i sit at a light for 30 seconds then pull away the car runs great for about 1/4 mile then starts to loose power. Fuel pump is ok and checked a bunch of other things and i can't figure it out. I guess i need to get a good scanner and see if its pulling timing. I wonder if when you idle at a light the PCM goes back to open loop then as you pull away it goes back into closed loop?
05-10-2009, 10:38 AM
#6
I pulled the passenger side coil packs and checked all the connections and swapped the 8 and 4 coils. Then made sure all the plug wires were good and connected properly. Took it for a 30 min ride around town and ran great. Well see how it goes though as the problem is intermitent. I have a laptop based scanner, but it never does it when its hooked up. Even when its not, the SES light never comes on when it misfires.
Once your car goes into closed loop, it shouldnt go back into open loop untill it cools back down, or when you go WOT and it goes into power enrichment mode. So under normal driving conditions it should stay in closed loop.
The best thing to do is to hook it up to a scanner and see what is going on when it does it.
Once your car goes into closed loop, it shouldnt go back into open loop untill it cools back down, or when you go WOT and it goes into power enrichment mode. So under normal driving conditions it should stay in closed loop.
The best thing to do is to hook it up to a scanner and see what is going on when it does it.
