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Cylinder misfires or bad injectors, please post here.


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Looks like I get to join this club.

 

Bought my 2006 Legacy GT in December of 2012; the previous owner had just replaced the engine and it had maybe 10,000kms on it when I got it. Since then, I've put about 40,000 more kms on it. Slowly been upgrading components (nothing internal, though), and it's now at Stage 2. Installed Killer B equal length headers a couple of months ago, and have had sporadic P2096 (Post Catalyst Fuel Trim System Too Lean) CELs since installing the headers (which seems par for the course, so I wasn't worried).

 

Then the wife takes the car for a business trip and of course about halfway there the car starts throwing CELs left, right, and center. I had her pull the codes on the AccessPort and they were P0303, PFFFE, PFFFF, and another P2096. I had her reset the codes, and immediately after that, the car started stalling. It's now sitting at a dealership, so I'm waiting to hear their diagnosis.

 

I'm hoping it's something simple like the injectors, coilpack, O2 sensor, or MAP and not burnt valves (which seems unlikely given that it's cylinder 3 misfiring instead of the usual cylinder 4).

 

Maybe the P2096 codes prior to this were actually pointing to the front O2 sensor on its way out?

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Update: thankfully, a simple fix. Dealership moved the injector to another cylinder and the misfire followed. Should have it fixed by the end of the week.

 

Also gives me an excuse to upgrade the injectors (not right away, but soon).

:icon_twis

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  • 1 month later...

had cyl 3 misfire due to poor coil pack connector, replaced coil pack just in case. Drive and idles fine now, except when it high boost it does sort of a stutter/surge and Roughness count in Cyl 3 goes up.

 

injector or plug??? maybe the poor connection and misfire fouled up the plug a bit

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uh oh... cyl4 misfire and Pfffe code...hoping it is just an injector..I haven't done anything yet.. (swap injectors, coil packs etc) but I am worried of the cascade of events even if it is "just" an injector.
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Wagon has got worse with misfires. Car is very rough at idle, but smooths out as soon as I am on the gas.

 

I did some logging with Tactrix cable and saw at idle cyl 2 misfire/roughness counts just kept going up, all other cyl at 0. But as soon as I hold revs at about 1500rpms or higher 0 misfires even on cyl 2.

 

The car has started making ticking/rattling sound from the engine at idle as well, but goes away with the revs like misfires.

 

Any idea what it could be? i tried swapping injectors with a used set of injectors from STI also put in new coil pack but nothing fixed it. also replaced both oil control valves, 1 was bad for sure. Could it be burnt valve? or intake manifold O ring going to cyl 2?

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cyl 4.. 65psi...ringland failure on a built motor w cosworth pistons....:(:( .. pro tune, crawford AOS, brad penn oil every 3k, lower rev limit, WTF????... I might be done... pouring $ into a depreciation asset is never smart but I just put in a new clutch/flywheel ,new TMIC, new turbo, had the ECU replaced (actually thanks subaru, they paid for 1/2 of that) .... I should just buy a merc 4wd sprinter van and put a shifter kart in the back to get my jollies off...:( MOTHER PUCKER!.... so put in a new motor ($6k) drive it for a year or two until the RS comes out or part this sucker out and never look back..? I know you gotta pay to play but...man..this hurts. Edited by derkahn
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Huh. In any case you may have been running lean at times and got some pretty good detonation...That would be my guess anyway.

In any case, if you ever decide to rebuild, I would make sure that after that you view at all times at the very least A/F learning and A/F correction gauges, Feedback Knock (FBK), and Fine Learning Knock (FLKC).

The A/F learning gauges should usually stay within +/- 5%, which would tell you that you are free of boost/vacuum leaks, and that your o2 sensors are working OK.

Keeping these variables within the above mentioned ranges should also keep you free of detonation, thereby leading to rare events of FKC and free of FLKC. Usually, when an engine is in good shape, FLKC should be zero everywhere. Hope that helps.

 

Disclaimer: I am no tuner :)

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Thanks for the advice... here is kinda my issue/complaint/armchair diagnoses... so as far as A/F learning,correction, FBK FLKC etc.. I have watched these , however I wish there was some sort of programming to put into a map etc to warn of this stuff.. realistically its a bit of a PITA to always have the accessport out (then put it away as not to tempt thieves) and also be watching that all the time.. I just want to get in my car and drive (insert you should have bought a higher HP stock sports car(insert car of the month) here), I think I saw a thread on NASIOC a while ago about people complaining about the cars knock sensors/system etc and how it doesn't lend it self to high performance cars..?? I don't really remember. I have been in a subaru that had knock before and really bad knock is pretty hard to not notice... Since I am the only one who drives this car I can't say that I have ever had a moment where I noticed something not right w the motor prior to this... Here's my armchair diagnoses.. maybe .. I recently read on the injector dynamics website ( I think) an article about filtering fuel (especially e-85) and how the oem system may not do an adequate job of filtering (I have seen lots of guys put an inline fuel filter in the engine bar w a servicable element/filter) and since cyl4 is so close to the turbo/up pipe etc the heat/heat cycling might shorten the service interval of that injector , especially if the fuel is not filtered adequately. I imagine a 1000cc injector running a few % points off of the others at WOT might just cascade into kablooey... totally guessing.. /frustrated.. but on a + the car still runs well at anything other than idle....? maybe the cure for ringland failure is all boost all the time..:( kidding..
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  • 1 month later...
ive got an 05 gt wagon i just got that ran really good but was throwing lean bank code. fixed it with a new beatshcwerks fuel pump, but now it idles and drive fantastic except when i get on it at all. it keeps misfiring in then. i know the main culprits but im just wondering what the most likely suspect is to start. again it only misfires when i put the peddle down halfway or more. if i im just driving around without punching it i get no codes. spark?
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the code is just cylinder 3 misfire code p0303 or whatever obd says misfire cylinder 3. dont know what the pressure is actually at. i guess im just wondering which is more likely, fuel or spark? Edited by brett76
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I have tried everything the shop and I can think of - new OEM coils, injectors taken out cleaned and tested, but we continue to get service engine light. Compression is good. Does anyone have a suggestion for a 2009 Legacy GT. A nice performing auto when working, but this engine problem and the dash that is "sticky" has made this less than a desirable car. Any suggestions?? Thanks, Dorothy
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Have the valve clearances checked.

 

Yeah. You may have to do that. Usually a good sign that valves clearance is off (usually have become too tight) is rough idle when engine has warmed up. I just experienced that and am currently adjusting my valve clearance (one exhaust valve no longer had clearance). And if it is the case, you do not want to wait and keep driving the car, or you will end up with a burnt valve.

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