Trying to resolve misfire codes p0302 p0304 p0301

[yosty]

Working my way through Donkey's misfire problem list...
IF YOU HAVE A MISFIRE CODE ,PLEASE READ THIS!!!

Events:
-flashing CEL with p0304 and p0302 in VT on Jan 1, cold morning, uphill, loaded car. Panic!
-drove around a little staying out of boost
-reset ECU (CEL returned)
-Changed fuel filter (no change)
-dry gas and full tank of 93
-drove to PA staying out of boost (CEL still flashing intermittently)
-upon arrival had p0304, p0302, p0301
-replaced timing belt and pulleys/tensioner, new thermostat, new plugs NGKIridium BKR6EIX gapped to .029.
-Leakdown test showed all cylinders under 5%
-no change
-unplugged MAF, no change.
-drove 5 miles, no change.

Next steps:
-clean MAF
-check FPR hose
-try alternate, stock ECU
-run can of BG44k
-clean grounds
-remove SPT intake and try stock airbox
-I have fuel line leak warranty repair scheduled for next week. Could it be related?

Anyone have any insight?

[Ruh Roh]

do you have a tune on the car or still stock map?

[yosty]

do you have a tune on the car or still stock map?

PO told me it's Cobb AP stage 2, but said he had lost the AP...

When I first got it it would boost to 15 psi and hold it but it had a bad up-pipe leak. Since I replaced the up-pipe with a Perrin one it would boost to 15 then oscillate down to 10 and settle at 13. Also, never threw an EGT code when I swapped the up-pipe. So leads me to believe it's not stock.

Will try a stock ECU tonight and also Meeting up with someone with a Tactrix cable so hopefully I can find out what's on my ECU.

Engine Mods (that I know about):
TBE, Perrin Up-pipe, SPT intake.

[yosty]

Update:
-MAF cleaned, no change
-stock ECU swapped in, no change except car is slower
-grounds cleaned (2 on top of intake, 1 by battery, 1 on pass sidewall), no change
-Checked the car with a Tactrix cable, it's only pulling timing around clutch engagement... Does that mean anything?
-Put in a can of BG44k and got some gas (93 oct). So far driven about 20 miles on it, haven't noticed anything different

At idle the car knocks badly and seems to be running on 3 cylinders. I get a p0304 within 20 seconds of starting it after an ECU reset.

Once moving it seems to run fine but blinks the CEL once in a while and after driving I'll have some combo of every misfire code. p0304 and p0302 always, P0303 usually, I've only seen p0301 twice. No other codes.

Next up:
-back to stock airbox
-FPR hose (need to find more info about exactly where/what the prob with this is)
-fuel line recall
-test/replace #4 injector

Other ideas?

[Donkey]

Until you do everything on the list there really is nothing else to offer. That was kind of the point of making the list as it pretty much has almost every single possible cause listed. How long have you had the car? Does it actually drive like it has a misfire or does it drive normal? Does it have a lightned flywheel?

[yosty]

Until you do everything on the list there really is nothing else to offer. That was kind of the point of making the list as it pretty much has almost every single possible cause listed. How long have you had the car? Does it actually drive like it has a misfire or does it drive normal? Does it have a lightned flywheel?

Had the car about 2 months. I fixed an uppipe leak and replaced the front 02 sensor when I got it and it ran great until New Years Day.

Drives great once moving. Idles badly (knocking, shaking).

[Ruh Roh]

what mods are done to the car besides stag 2 AP tune and SPT intake?

[yosty]

what mods are done to the car besides stag 2 AP tune and SPT intake?

TBE, Perrin Uppipe, SPT intake. Those are the engine mods I know about.
When I did the timing belt, I put in a stock thermostat, believe it had a low temp before that.

135k miles. dealer replaced headgaskets @ 72k. Was at dealership every 3k-5k miles until 90k.

[yosty]

Update:
-Put in stock airbox, no change.
-FPR hoses and other vacuum hoses seem fine (sprayed starter fluid around with engine running, no change in idle speed)

Above 1200 rpm engine stops shaking and noise goes away. Below that speed I get an obvious shake in the engine that seems to me as if its running on 3 cylinders. Also a noise that is a deeper and much louder version of the normal Subaru ticking noise.

My current hypothesis is that my number 4 injector is leaking and causing the idle mixture to be too rich. At higher load (and higher fuel delivery) the effect of the leak would be less significant and the mixture might still be combustible.

Plan:
-continue to run through tank of gas with BG44k in it. (ordered gm top end cleaner, will try it when it arrives)
-fuel line recall will be done at dealer on Wednesday, if problem is still happening I'll have them test my injectors while they have the intake off for the recall. (can anyone confirm they do have to pull the intake to do the fuel leak recall?)

If that doesn't work... No idea.

[yosty]

Confirmed. Dealer will pull the intake manifold for the fuel line recall:


Car goes in to dealer tomorrow, will request compression check and test #4 injector.

If it fails compression I'll be very sad and I'll suspect valve clearance.

If #4 injector fails, DW 650s are going in and then I need a tune.

If neither I'm stuck.

[yosty]

30psi cylinder 4!
160psi all others.

Nuts. I suspect tight valve clearance burned a valve...

Gonna pull the engine next week, either swap in JDM or refresh my heads and throw it back in.

[yosty]

Burned exhaust valve number 4 cylinder!

Well at least I know for sure what it was now.

[zax]

Did you do a leakdown test to conclude it's the exhaust valve?

[yosty]

Nothing showed in the original leakdown test. Only in the compression test. I concluded it was the exhaust valve when I pulled the heads and looked at the valve...

[loooshman]

What the F cause that? Not a pretty valve there!!