- Joined
- Mar 5, 2014
- Posts
- 639
- Reaction score
- 202
- Location
- Kansas City, Missouri
- First Name
- ryan
- Truck Year
- 1987
- Truck Model
- r10
- Engine Size
- 350
My buddy has a 2008 Silverado with the LY5 LS motor with a slight hesitation in the engine. Start up is fine but after that he said he noticed it. Well it threw a code P0307. He looked it up and found it was for mis-fire in cylinder #7. He asked me about it and I told him I am not much help with computerized engines. I only knew of GM having a common problem with the LS motors mis-firing.
The CEL went off a day or so later but the hesitation is still there. He pulled the spark plug on #7 and noticed the threads had oil on them, the porcelain was cracked and white powdery stuff on the tip of the plug. He replaced the plug just to help the hesitation, which it did, but he asked me what would cause that.
I have no clue. All I could think is maybe the rings are going bad but if he were to do a compression test he'd know for sure if they were or not. He read maybe there's a gasket bad but I wouldn't think a head gasket would cause all that.
Cracked porcelain could be pre-ignition so maybe there's something wrong with the ignition system, bad coil??
Anyone out there with an LS motor experience the mis-fire or other issues like the oil on the threads or cracked plug??
The CEL went off a day or so later but the hesitation is still there. He pulled the spark plug on #7 and noticed the threads had oil on them, the porcelain was cracked and white powdery stuff on the tip of the plug. He replaced the plug just to help the hesitation, which it did, but he asked me what would cause that.
I have no clue. All I could think is maybe the rings are going bad but if he were to do a compression test he'd know for sure if they were or not. He read maybe there's a gasket bad but I wouldn't think a head gasket would cause all that.
Cracked porcelain could be pre-ignition so maybe there's something wrong with the ignition system, bad coil??
Anyone out there with an LS motor experience the mis-fire or other issues like the oil on the threads or cracked plug??
