Hey ya'll

 

I did a fair deal of searching on the forum for misfire issues....there are many....and I'm running out of ideas of what to do and where to go.

 

So:

99 legacy w/ ~186k just got:

Heads machined, total reseal, timing / water pump / t-stat / pulleys, new clutch / throwout bearing, 5MT w/ ~80k, new knock sensor, plugs & wires (oem), and a coil. She also had both cat's removed.

 

And the evil thing is misfiring. It is subtle at first, like a slight hesitation with a small amount of power loss, but it gets bad when the car is under load...like pulling up a hill and then misfires badly and has massive power loss. I've noticed that this is mostly when the car is running between 2.5k and 3k rpm. Usually if i'm above 3k rpm it won't mis.

 

I've had a p0420 code forever. Both o2 sensors have ~25k on them (oem).

 

Please help.

what kind of spark plugs are in it? bosch platinums? if so, put NGK's in it. just a thought

Could be a lot things , since work was just done and it didn't do it before, I would check easy stuff first. Vacuum leaks( loose/ off/ cracked hoses) did you replace your injector o-rings? ,valve clearances, compression. Move injectors around. What cylinders are misfiring( codes)?

I've had a p0420 code forever. Both o2 sensors have ~25k on them (oem).

 

just out of curiousity - when is the last time codes were checked and/or reset? it is possible there are other codes stored, but you wouldnt know if the CEL is on all the time.

 

When my O2 went south it caused some major driveability issues, no power, misfires, car was pretty much undriveable for more than a few minutes - warmed up = closed loop = major problems.

 

and - just because a sensor has ~25K on it, doesnt mean it isnt bad...

Your front 02 sensor only has 25k on it, and that in itself sounds too young to fail, but since you had so many other things done to the car, perhaps the other issues led to early failure in your front 02 sensor. Bcuz, if this misfire under load problem is only happening when the car is warm..........your symptoms are classic front 02 sensor signs. My front 02 sensor needs replacing every 40k miles like clockwork. 2001 Forester with 112k on her.

 

I say replace it, and report back here.

What about cam timing? One tooth off will cause very similar misfiring issue.

Plugs and wires, how old are they, what brand are they?

Is it a missfire or power loss... like a overly active knock sensor?

What about cam timing? One tooth off will cause very similar misfiring issue.

Plugs and wires, how old are they, what brand are they?

 

Ca-ching!!!!! We have a winner. Cam timing off ONE TOOTH!

 

 

Now I can sleep at night!

 

Thanks ya'll!!!!!