I need some ideas here, I've got a rough running Evo8. It idles with a miss, and sounds like a Suby around 2000 to 2500 rpm , The code is P0301, cylinder 1 misfire. Here's the details:

The #1 plug is getting black on the porcelin, not oil but seems to be alot of fuel. It is still firing however.

The other 3 look too light on the electrodes, like it's pulling fuel and burning those hot to compensate on the front O2 (I have stock ECU)

I am making 17-20 vacuum (comp cams) and will still hit full boost.

I have reset the ECU, no change

I have swapped the coils around, no change

I have swapped plugs, no change

I have swapped the injectors, no change

Compression test is 170 accross

Cam angle sensor has not been damaged

Cam timing is still in line

I have measured voltage on the fuel injector harnesses, seems to be the same but I do not know the actual proceedure for testing this

Strong spark from the #1 plug wire, arcs far

I reflashed to stock today, no change, flashed back, no change

UPDATE: Swapped out plug wire to #1, no change! I'm starting to get worried there is something not right with the ECU.

Any ideas?

 

BURN YOUR CAR it's been infected with the soul of a DEMON....SCOOBY DEMON!

 

This is the only way.

 

Seriously though, have you replaced your spark plug wires and coil boots? If not, do it.

 

Not the wires, They ohm out ok... they're probably next on my list however, I noticed when I was doing the compression test that the plug in #1 was getting doused with fuel, quite a bit more than the other 3, that obervation kinda pointed me back towards the fuel

I think I can borrow a coil wire from one of my friends to test, I'll see.

 

 

Check the wire for crack or little holes. it maybe grounding out to the head before getting to the plug.

 

Yup, had that happen to me on another car... this "looks" good, and if I have the throttle set to where I can hear the miss quite clearly, I can move and bend that wire all over the place but it never clear up the problem.

From what I can tell from that test as well as the ohm meter, it seems ok, but I'll be trying to get my hands on one to test anyways.

Just in case that does not remedy the problem...Anyone ever heard of any ECU related problems causing bad signal to be sent to just one injector?

 

bobrick beat me to my idea. i know exactly what your car sounds like too. i had a spark plug blow out a few weeks ago, even shattered the plug cover. took out the wire out with it. crazy loud subbie sound. driving through downtown philly like that was a pain. good luck diagnosing.

 

cant be a subaru since it is obvious you can easily get to your spark plugs.

 

lol true

 

Check the plug boot if its arcing to the head. Had it happen to me and was a pin hole in the boot.

 

Just because the coil wires ohm out okay doesnt mean that theyre ok. There could still be a short (easier path to ground).
Unless a transistor went faulty in your ecu I would think that its okay. You could swap with a friend.

Take a clean spray bottle with water and spray some mist over the plug wires at night and look for a spark, or tune a radio to an AM station, point the antenna on the plug and listen for the least "popping" noises.

 

if that was the case the misfire would have changed cause he swaped the coil packs i would swap the injector to cylinder #2 if the misfire moves you know its a bad injector

 

Its got to be the coil wire