P0300?

[ThunderBolt]

I've been getting a P0300 random cylinder misfire since my truck has had the 6.0 put in. It was running fine but just spuddering a little on the upper rpms. I had the plugs regapped to 45 thousands from 35 thousands and it stoped; my truck ran fine except for the check engine light that would come on and off periodically and flash every now and again. It would stay on for a day or two, then stay off for a day or two. It ran for about three weeks like this and well all of a sudden, my truck is misfiring really back and just about every time i get into the gas the check engine light flashes at me. It probably has about 1/3 the normal power and you can definitely feel the misfire. Allen said this is due to the larger cam and I'm waiting on a pcm with the P0300 code disabled. Will this fix it? And why did it run fine for so long and just now its doing this??

[GasGuzzler]

Disabling the DTC will not make it run right, just keep the light off for misfires. You need help, most likely mechanical. Get a real diagnosis....a scan can tell you which cylinder has a lot of misfires. This can narrow the diagnostic approach. This can lead towards a compression test, running compression test, leak down test, etc.

[ThunderBolt]

I had a real diagnosis done and the shop put new spark plugs in and regapped them to 45 thousands. The light stayed off for a day then it started coming on and off about every other day. I want to take it back up there but i know they're just going to try to charge me more money cause it's been awhile.. even though that didn't fix the problem!


Edit: Turns out to be a burnt plug wire! ha

[GasGuzzler]

Glad you found it.