Ej25 swap into 99 Impreza - P0304 Cylinder 4 misfire

[AdventureSubaru]

As the title states. Put an EJ25 from a 2000 Outback into a 99 Impreza OBS replacing the Ej22 in there that had a rod knock.

 

Both Phase 2 motors. The only differences being dual port for the EJ25 which I swapped the y-pipe and the Ej25 has a plug where the vac hose for the cruise control runs so for now I just plugged the cruise vac hose as well.

 

Started up after a little cranking and starts every time afterwards. After running for about 60 seconds I get the flashing check engine light which is P0304 Cylinder 4 misfire on the scanner. Luckily the old EJ22 was running fine so I can swap parts to check.

 

swapped #4 plug wire and reset the code. No change.

 

Swapped #4 spark plug and reset the code. No change.

 

Swapped the coil and reset the code. No change.

 

Next step I guess is to check timing to see if it maybe jumped? Other thoughts of what to try? Spark plug looked well used but not overly dirty. No oil in the plug tube. No external leakage of the head gaskets.

[lstevens76]

Did that EJ25 get a compression and leak down test before you started swapping?

 

Also, did you swap the appropriate sensors and/or cam/crank gears?  

Edited June 15, 2015 by lstevens76

[idosubaru]

there are two different timing triggers on the back of the drivers side cam sprocket and crank sprocket.  did you verify both are the same or swap them? 

you want to retain the sprockets/triggers to the vehicle/ECU.

 

did you hear the "new" engine run before the install?

 

1. verify those or swap them

2. check timing marks

3. check valve clearance - exhaust valves being the most likely culprits.

Edited June 15, 2015 by grossgary

[desertsubaru]

Try what istevens said first and if that does not help read this thread. http://www.ultimatesubaru.org/forum/topic/96703-p0304-issue-solved/page-2

 Also even if the plugs look good put new ones in to eliminate that part of the problem.

[AdventureSubaru]

I try to take people at their word, so I was assured by the seller that the motor ran fine - no issues. He had bought the car as a donor for the transmission after it had been in a light side collision and sold it to me. My own fault if he pulled a fast one. Would be the second time i've been taken on a Subaru motor, but I'd like to think that most folks aren't such trying to make a buck off of me by selling bad motors as good ones. Subaru crowd in particular. I don't have a leak down kit, but if the other options turn no results, I'll find one.

 

I did not swap crank and cam pulleys. I thought it was 2003 that they changed and that 99 and 2000 should be the same. Did a different swap on a friends car a couple weeks ago putting a 99 Impreza 2.5 into a 2002 outback and it has been fine without swapped pulleys. Maybe different between the Ej22 and EJ25?

 

Good lead in that thread. I had just thought of the injector. I just swapped that out with one from the EJ22. Again no change. Figured it was worth eliminating since it was an easy option.

 

Going to check timing next. Shouldn't I be getting cam or crank sensor codes if timing or pulleys were the issue? Or would the car need to run longer before codes would be thrown?