Please help! Been trying to diagnose misfire for 3 months n

[Zac]

Been trying to diagnose a misfire on my car for almost 3 months now. I just put it back together yesterday after I cleaned out my whole fuel system but it still misfires :(

It ran well for 5 minutes but it went back to crazy misfires on all cylinders right after. Again no codes :(

I have changed the MAF, both O2 sensors, cam sensor, crank sensor, plugs and wires numerous times, coil back, fuel filter. compression test is good, leakdown test is good. Vacuum readings are spot on, fuel pressure is great.

I cannot find whats wrong, someone please help :(

[green97gt]

sounds like it may be about time to sell it.


It ran well for 5 minutes but it went back to crazy misfires on all cylinders right after. Again no codes

"crazy misfires on ALL cylinders"?

no codes? so how do you know its misfiring? and on what cylinder?

lack of power? doesnt run right? what? your not giving alot of info here to work with.

some of the tests you did are redundant, like if you have good compression, there is no need for a leak down test, etc.

post a vid maybe? i think iv said that before.

"ran fine for 5 minutes" like it got to operating temp? or?

do you have any friends with cars like yours you can test yours/your parts against?

have you looked into grounding issues?

or voltage issues?

or are you just throwing parts at it?

[Zac]

sounds like it may be about time to sell it.


It ran well for 5 minutes but it went back to crazy misfires on all cylinders right after. Again no codes

"crazy misfires on ALL cylinders"?

no codes? so how do you know its misfiring? and on what cylinder?

lack of power? doesnt run right? what? your not giving alot of info here to work with.

some of the tests you did are redundant, like if you have good compression, there is no need for a leak down test, etc.

post a vid maybe? i think iv said that before.

"ran fine for 5 minutes" like it got to operating temp? or?

do you have any friends with cars like yours you can test yours/your parts against?

have you looked into grounding issues?

or voltage issues?

or are you just throwing parts at it?

Checked all my grounds, voltage and charging systems are fine.

never got up to operating temp really.

no friends with cars like mine.

I've posted a video a long time ago.

its not driveable at all.

http://s635.photobucket.com/albums/uu80 ... V00045.flv (http://s635.photobucket.com/albums/uu80/Zac86/?action=view&current=MOV00045.flv)

[green97gt]

i just dont see how the car can be "misfiring" that bad, like in your vid and the CEL not come on cause the speed of the crankshaft has changed.

that vid almost seemed like the car has an idle control issue.

if you give it gas, anything change?

OR the ECU is toasted to the point where it cant recognize a misfire.

[Zac]

uploading a video as we speak. Also added some seafoam into the tank to clear out any moisture if there was any.

[Zac]

http://s635.photobucket.com/albums/uu80 ... 0104-1.flv (http://s635.photobucket.com/albums/uu80/Zac86/?action=view&current=MOV00104-1.flv)

Ok after the video I put in my new MAF and made sure the coupling was sealed and just put in a full tank of premium gas.

Drove about 30km on the highway and the misfires are back :(

[Zac]

GOT A CODE!!!

PO325 Knock sensor bank 1 sensor 1

Could this fix all my problems?

[ouch1011]

No, knock sensor will cause a lack of power but not stalling or anything like that. That is most likely a false code because Subarus try to function test the knock sensor by forcing detonation. It probably is not getting the engine to ping like it wants in its current running condition so it set a code.

When this problem first started, what was the car doing? Were you driving and it just started misfiring, or did this start after the car sat? What was the fuel pressure? Did you check it while revving the engine and having it misfire?

You might also check and see if the engine runs better or worse when injecting a supplementary fuel source. Also, has the engine ever backfired? If so, out the intake or the exhaust? If it is running lean, it will pop out the intake, if it is losing spark, it will backfire out the exhaust. Also, if it backfires for a while, does it get a strong fuel or sulfur smell, or no real strong smells? There are tools that can be used to determine if you are losing spark or fuel injector pulse, but I'm guessing you don't have them.

[Zac]

was driving when it first started.

Checked fuel pressure while it was misfiring and it was still good.

[green97gt]

so what happens when you start it anf give it some gas?

[ouch1011]

Most of the suggestions I have for diagnostics require tools you probably don't have access to (scope to check signal output from crank/cam sensors and ignition secondary pattern, inline spark tester to see if you have weak/loss of spark, noid light to check injector pulse).

Where is the tach tapped into for its signal?

[Zac]

tach is connected to blue wire on the coil pack.