random misfire

[mason313]

I have an 04 yukon denali with gutted cats, cat back exhaust and an cold air intake. I replaced my plugs and wires maybe 1k mikes ago but still have a random misfire only other code I have is for an 02 sensor. the truck mainly misfire on the freeway over like 70 mph but it is getting worse. any idea what it could be guys thanks

 

[Tonyrodz]

I also have this issue in my 03. Only have the misfire code tho. Mine doesn't run any different as the check engine light flashes. In town I don't have this problem , only on the highway .Subscribed. I was told it could be a coil pack.

 

[mason313]

yeah there really isn't any noticeable difference when the light is flashing. I've hooked it up to a snap on scanner and all of the cylinders miss fire randomly even at idle but the light doesn't flash.

 

[Tonyrodz]

How many miles do you have? I'm around 274,000 but I've had this problem for awhile .If you're having random misfire on random cylinders, think it could be fixed just by swapping all the coil packs?

 

[mason313]

I'm at 185k I've had this problem for awhile too. there not very cheap to just try it and hope it fixes it tho lol

 

[Tonyrodz]

A few times I got the dreaded reduced power too .Fixed itself, so far .Ever get that one?

 

[mason313]

I have but that was from a broken wire on my tps

 

[Kingx1]

Anyone else with this random misfire code? Has anyone resolved theirs yet? I had my cam and crank sensor synchronized at a shop the other day. Still has a misfire though. Shop told me it was fixed and it obviously isn't. I think it runs a slight bit better since, but the rough idle is still there. Its annoying cause I know I should have more power. I'm thinking about taking it to get an injector cleaning done.

 

[jarydM]

Anyone else with this random misfire code? Has anyone resolved theirs yet? I had my cam and crank sensor synchronized at a shop the other day. Still has a misfire though. Shop told me it was fixed and it obviously isn't. I think it runs a slight bit better since, but the rough idle is still there. Its annoying cause I know I should have more power. I'm thinking about taking it to get an injector cleaning done.

i got this one and the O2 sensor code. Replaced the O2 sensor and everything went back to normal.

See if you random misfires are all on one side, if they correspond with the O2 sensor, thats most likely your culprit.

There is a process to check the coilpacks thats fairly easy, but i have it wrote down at home, and I'm not at home

 

[Kingx1]

i got this one and the O2 sensor code. Replaced the O2 sensor and everything went back to normal.

See if you random misfires are all on one side, if they correspond with the O2 sensor, thats most likely your culprit.

There is a process to check the coilpacks thats fairly easy, but i have it wrote down at home, and I'm not at home

Really? Mine also has a loss of power on acceleration that feels like its being held back. Did you have this too? I think I'll try to find this coil pack check procedure online if you don't have it.