tracking down a crazy cylinder misfire ***Fixed

[idosubaru]

*please don't post obvious solutions or not read what I've already done, because i've covered all the obvious things for misfires.

 

I got a complete motor (blown block) to finally fix this drivers side both cylinders misfiring issue. both 2 and 4 misfire codes and it's driving poorly, though drivable.

 

New spark plugs, wires, coil pack, igniter have done nothing.

Happens immediately at start up so it can't be the O2 sensor.

 

Has perfect compression and timing.

 

I smell fuel and it changes to worse when an injector is unplugged so it's getting *some* fuel.

 

My plan is to:

 

1 swap the entire manifold

2 check valve clearance

3 swap heads

 

Missing any thing else?

Edited April 30, 2011 by grossgary

[idosubaru]

Swapping the intake manifold fixed it. I assume the fuel injectors or supply was bad?

 

Anything else on the intake manifold that could be bad - fuel pressure regulator, could that affect only one side (down stream side?)?

 

Honestly I had zero confidence this was going to fix it. I was so confident it wouldn't that i reused the intake manifold gaskets.

GAH!

Edited April 30, 2011 by grossgary

[Fairtax4me]

I'd guess injectors, or the old manifold was cracked or improperly sealed and getting too much air. OR maybe it had a mouse nest in it and wasn't getting enough air?

Either way, Glad to hear you got it fixed!

[idosubaru]

I'd guess injectors, or the old manifold was cracked or improperly sealed and getting too much air. OR maybe it had a mouse nest in it and wasn't getting enough air?

Either way, Glad to hear you got it fixed!

looking for leaks, i sprayed all around the manifold, so shouldn't be seal/leak/air/crack.

 

now - the mouse nest....it did sit for awhile, i should check the intake runners, that would be funny.

 

otherwise i guess it was the injectors, want to find out as i could use this manifold later for a spare set of heads i have.