I have an 06 3.7L v6 with 99000 miles and this code keeps appearing for a random misfire. iv taken it in and its an 06 so I don't believe its a vacuum leak. theres been seafoam cleaner put into the cylinders to remove excess carbon which has helped a bit but not fully. fuel injector cleaned and that didn't help either. the mechanic says now its a valve compression problem saying valve 4 has about 80% compression. I don't know if that's fully whats going on because this Is the 3rd different prognosis they've given me. plus it does still run fairly well just the cel wont go off. any ideas?

 

I have the same exact thing going on in my 06 quad cab 4.7l 4x4. I'm gonna check the coils tomorrow and see if it's that. Then check vacuum leaks. Does yours stutter a little on slow acceleration but fine when you floor it?

 

I would take the truck to another shop for a second opinion, but before you do that, ask that mechanic what the compression readings were that he got and whether he did a leak-down test at the same time. In my opinion, 80% (where ever he got that value from) should still be within allowable specs & that alone shouldn't give you a misfire code. Often, the issue is a lot simpler, like plugs or coils. Plugs are often overlooked because people see no distributor, no wires and have a misconception that the plugs can last forever. With the high energy ignition design on modern engines and the quality of the plugs, they will last for a long time, but they will burn a gap so wide that the spark will occasionally not happen. I changed a set that had no outward appearance problems but the gap was .020 larger than spec.

The computer has no way of knowing what the spark looks like, so it won't give you a CEL, all it knows is that it's occasionally stumbling.

 

yes that's exactly what happens actually!

 

Take it to a shop and ask if they do free scopes, they have a scanner that'll not just tell you what's wrong but why it's happening. I'm gonna check my coils tomorrow

 

I had one once, never popped back up. THis code can also happen from a dirty or malfunctioning MAF sensor. I had this happen on my Crown victoria, and it was the same day that I got really cheap gas. I ran the tank empty, put techron fuel system cleaner in the tank, and I filled it up. I think I had bad gas since it hasn't happened since. USually if a coil is bad, it will pop up a code for an exact cylinder that is misfiring. Hell, this code can also happen from dirty injectors.

 

If you think its a coil. Move the coil to another cylinder. If the code changes then its the coil

Say u move the coil to cylinder number 1 and now the code is on cylinder 1.

Boom Problem Solved.

If the code stays the same, then it could be an issue with The Valves but thats unlikely.

 

^but the code is not a specific cylinder.