Hello folks, I have a 2006 5.3l Yukon CL 1500 with a 4th cylinder misfire. Changed the plugs, the coil to check if the misfire would follow (it didn’t), cleaned the MAF sensor, cleaned the throttle body, ran some seafoam through the gas tank, and am just about out of ideas. Any suggestions?
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MassHoe04
Full Access Member
Not always, but sometimes... A camshaft position sensor can cause a misfire that stays with the same cylinder.
S33k3r
Full Access Member
You might also do a leak check around that cylinder.
rockola1971
Full Access Member
How old are the spark plug wires?
50,000 miles. This is the second engine on the vehicle. First engine failed at 110,000, with a 4th cylinder misfire. Engine was replaced. Still had the misfire, replaced the MAF sensor and the misfire went away. I replaced the MAF sensor on this vehicle when the code first threw, thinking it was the same thing.
I had a compression test and it came back as the same as the other cylinders, maybe like a 5psi difference.
I can take a look into this, I haven’t checked on a camshaft position sensor before so that’s something I’ll have to look up and see if I can find a YouTube video or something. Thanks
Like @S33k3r said, check for vacuum leak and maybe does have a failing injector. What does that plug look like, pics please.
By the way, welcome to the forum.
By the way, welcome to the forum.
S33k3r
Full Access Member
Do you know the specific code or codes it is throwing? I was thinking it could also be water or oil intrusion, but I think you would have noticed oil intrusion.
Yeah its throwing a P0304 code.
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