Po305 Misfire Cylinder 5

[Dantheman-2003]

UPADTE 2: Yes this is weird. So I put that stupid thing back on, CEL turns off with no codes. Drive it for a minutes and rough rough idle and throttle. CEL back on. I’m leaning towards vacuum leak or MAF sensor bad. My question is, that little air module in there pretty good. How did it just pop out?

Thoughts?

 

[OR VietVet]

UPADTE 2: Yes this is weird. So I put that stupid thing back on, CEL turns off with no codes. Drive it for a minutes and rough rough idle and throttle. CEL back on. I’m leaning towards vacuum leak or MAF sensor bad. My question is, that little air module in there pretty good. How did it just pop out?

Thoughts?

I have leaned in to look at things and hit that and pushed it out. That should have not caused a misfire. That is why I said what I said.

Maf effects all cylinders. You have a one cylinder misfire. At least that is what you have said. Vacuum leak or plug, IMO. The plug is easy to check, switch like I said.

 

[Dantheman-2003]

I have leaned in to look at things and hit that and pushed it out. That should have not caused a misfire. That is why I said what I said.

Maf effects all cylinders. You have a one cylinder misfire. At least that is what you have said. Vacuum leak or plug, IMO. The plug is easy to check, switch like I said.

@OR VietVet - good points and good call on the MAF. I’m back to the drawing board on this sob. But it’s odd that CEL went off and code disappeared when I put it back in. Nonetheless, tomorrow is another day.

 

[OR VietVet]

The CEL can pick whenever it wants to go out. A thorough test drive is always needed, if the light goes out by itself or is turned out, then reattach a scanner and check/double check for codes.

 

[j91z28d1]

I think it's interesting that it ran smooth for a bit when cold, warmed up and started to miss again.

have we seen the fuel trims and stuff in this one. maybe that alcohol % and running rich enough to miss?

 

[Dantheman-2003]

At this point I’m thinking maybe fuel or air issue. I’d be surprised if it was something internal in the cylinder. But we will find out. Gonna enjoy my weekend for now. On Monday I’ll take it into the steelership and have them diagnose it. $$$

Go from there. Will report back.

 

[OR VietVet]

Did you at least swap the spark plug yet? Check for vacuum leak? If is running rich or lean, that would effect more than one cylinder, IMO. But a vacuum leak or spark plug can narrow down to one cylinder.

If you take it to another shop, make sure they explain why whatever they find, is bad and documented. Good shops will even document their diagnostic steps and results of tests.

 

[mikez71]

maybe inspect coil wiring harness/connector?

 

[mikez71]

Did you at least swap the spark plug yet? Check for vacuum leak? If is running rich or lean, that would effect more than one cylinder, IMO. But a vacuum leak or spark plug can narrow down to one cylinder.

Vacuum leak, hmm.
I wonder if it's leaking at the intake manifold gasket.

 

[Fless]

We have no idea what the fuel trims are doing, if it's going into closed loop, what the MAF is reporting, etc. Without some live data and knowledgeable eyes on that, all we have is conjecture.

Once the dealer diags it, please let us know what they find.