Misfire Again

[tirwin88]

Back in mid July of this year I was having major issues with my truck including a misfire in Cylinder 1. Well just yesterday she started running badly again suddenly and within 5 minutes of hesitating when driving the check engine light finally came on. It is a misfire in Cylinder 1 again. We changed the coil pack and spark plugs. Any ideas why this is happening again so soon and which should I replace?

[maxwedge]

You need a proper diagnosis what does the plug look like, is the coil ok, spark to the plug, good compression, these are the basic initial diagnostics.

[tirwin88]

My daughters BF is supposed to come over and look at it today. Hopefully he can diagnose all of these. He did mention a possible injector but is only guessing really. After reading some posts here we never changed out the wires so maybe that is it as well.

[maxwedge]

There are no wires these are coil on plug ignitions, there is a short connector from the coil to the plug though.

[tirwin88]

Thanks Max...I knew that! haha. My daughters BF actually corrected me on that earlier. We are now getting a P300 code for multiple misfires and an odor is now detected. My daughters BF said it could be a fuel pressure regulator or bad gas. Gonna try an additive first to see if that corrects the issue. Your thoughts?

[maxwedge]

Low fuel pressure or a clogged filter can cause misfires usually not one cyl. though, but 0300 is random not one cyl., so you guys have your work cut out for you.

[tirwin88]

Not what I wanted to hear. The original code was a P301 and after clearning it is now a P300. The odor is a strong sulfur smell. Does that break it down to what it could be?

As much as I hate to do it..I am going to put it in a shop to be looked at. Just checked the ODB again and now the only code I am getting is a P301 (misfire cylinder 1) and not a P300. Knowing NOTHING about cars I am not up to throwing different parts in again hoping it will fix it.

[maxwedge]

Good thinking, a fulll scan can look at misfire counts, the exhaust smell is un burned fuel in the cat.