Multiple cylinder misfire. Any help appreciated!

[boxerboost]

Hey all,

So the other day, I was just leaving my driveway... car "chugged" a bit, and then CEL. CobbAP read that I had misfire codes on 1, 3 & 4. Reset the codes and it ran great for a while.... then while driving chugged a bit but no codes, this morning, backing into my spot at work, CEL turned back on, again, misfire on all cylinders.

I briefly described this situation to Mikey through txt and he suggested that it may be my crank sensor. I was just curious if anyone else had any suggestions/opinions? I'm not a genius w/ troubleshooting this type of issue, but could a bad coilpack or MAF sensor might cause the same symptoms? Any other ideas?

Thanks for the help!

~Brian

 

[drvsdwz]

Is it smoking out of your tailpipe at all? When its running, open your oil filler cap. Can you smell fuel and do you see smoke? If that is the case, it will most likely be bad piston ringlands. I had a run in with this a year ago.

 

[boxerboost]

No smoke or smells, just poor idle and it's "chugging."

 

[Meyagi]

it only does it once in a while, its not pistons. its prob a bad cam sensor or failing crank sensor. ive got a 06 sti here that's doing the same thing but it gave me a cam sensor code so ill replace that first. If you can get it to do it while im in the car I can prob give you a better idea whats wrong.

 

[drvsdwz]

as you know mike, it's been said before, hard to do a diagnosis over the internet lol

 

[Meyagi]

yes it is lol

 

[boxerboost]

Sorry I'm not much help with diagnosing!

I thought of a good explanation of what it feels like when I'm driving, though if it helps, Mikey.

When driving at any given rpm range/speed (seemingly more so when lower rpm, 2,000rpm or less)

It feels like the car is hitting fuel cut.. that's the type of "jerk" the car is giving, it's a little softer than what a fuel cut jerk would be, but that's the same feeling of it. Also idles real lumpy... enough so that it stalled on me once in traffic.

 

[boxerboost]

So the car is currently with Mikey... We've (and by we, I mean he

)

¤ Replaced the plugs

¤ Done a leak down test (Came out great, so that would imply it's not ringland, gasket, valve tension issues, engine)

¤ Checked the gas for water

¤ Checked the crank sensor

¤ Confirmed that it's not the altenator

¤ Confirmed that it's not the battery (though I need a new one)

¤ Reflashed ECU with Cobb AP2.0

Next up Mike's gonna check the cam sensors...

Running out of ideas as to what could be causing this misfire on all 4 cylinders, there's no other CEL codes being tossed that would imply anything else!?

Thanks for any input, as there's always more ideas from the collective!

 

[boxerboost]

Absurd, Mikey finally pinpointed the horribly obscure issue. Of all things, the K&N Filter (cone type) I have was resting on a bracket that somehow over time managed to lean over, the vibration of the engine and the "chicken wire" mesh of the cone filter managed to chaff it's way across a harness wire, that was exposed, and thus shorting. Bracket fixed and everything's running proper now! So silly that it ended up being something dumb like that, but at least I've got new plugs, and Aced a leak down test etc in throughout the process!

Thanks again for the help, Mikey!