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serious misfire issue!

10K views 26 replies 6 participants last post by  Brockton 
#1 ·
I have a 2007 subaru wrx AT with a stage 2 tune. Earlier this month i had a deer jump out in front of me and damage the whole front end. The body shop had my car for about 3 weeks to repair everything. They said they had someone check the motor of the car to make sure nothing was wrong with it. Anyways when i picked it up i was driving home and had no problem with it as far as feeling any power loss or anything, in fact once im driving the car theres no serious issue. Yet when i come to stop the rpms at first would fluctuate and now the car shakes and feels like its going to bog out but the rpms arent fluctuating anymore. It hasnt thrown any codes and just to be sure my check engine light worked i unplugged the MAF sensor and that threw a code so i know the check engine light works, but when i hooked my computer up to it and ran the romraider logger it shows roughness on cylinder 4 and only that cylinder. It misfires the whole time i sit at idle but never throws a code. What could cause this?


Ive replaced the spark plug and switched coil packs to see if it would follow but it still shows on cylinder 4. Ive read where an injectore could go bad or could be a compression issure, but every thread i have read about this people have had codes thrown. Could it be somethin as simple as bad gas doing this? I will say as the tank has gotten lower the shake has gotten worse. Is it possible the body shopdrove it around and then put like a gallon or 2 of the wrong gas in my car and cause this? Or would that cause all the cylinders to act like this. Any ideas would be helpful before i have to go spend the diagnostic money from subaru when i might be able to figure it out myself.
 
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#2 ·
Sounds like a vacuum hose is misplaced or not hooked up correctly. I haven't a clue what they would mess with if it was just body damage. Did they do any pulls on a frame straightner?

Take it back to them if in doubt.
 
#3 ·
No looking over the paper work for what they did it doesnt say anything about messing with the frame. I know they had to mess with the radiator cause they had to fix the condensor and i know they unhooked all my coolant lines and a/c lines but not sure if they unhooked a vacuum line ill try to look down all the hoses again to be sure. Any particular vacuum hose to try to look for that would cause an issue on just one cylinder like that
 
#5 ·
my coolant reads between 190 and 200 at idle and while driving. i attached a learning view of my car. I also have swapped my injectors around and changed plugs and switched coil packs around again just to be sure. Still getting the same effect but the shake is not nearly as bad as it has been since i've added fuel injector cleaner and put new gas in it. still gets a misfire on cylinder 4 without throwing codes but now its being even more random with my logs because i can sit at a light and it won't start misfiring and then drive a little bit and stop again and it will start misfiring again. the dealership is telling me it could be a valve clearance issue or the ringland on the piston. Personally I would think if it was a ringland issue it would be more serious then what i'm getting but i could be wrong i guess. i might just go ahead and pay the 100 bucks for the diagnostics from subaru and see what they say because Im really running out of ideas on what could cause this. unless you might have an idea.

Also I cleaned the maf sensor and sprayed intake cleaner around the vacuum lines while the car was running to see if it would get sucked up by any of the lines and no luck with that.
 

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#6 ·
I'm assuming they had the battery unplugged for quite a long time. It could be bad gas or the realtime map is fubared and is rebuilding its self. Is this all in the same day you picked it up or over the course of a few days?
 
#9 ·
I havent used seafoam yet. I did use techron fuel injector cleaner when i filled up but im gonna try to use seafoam when the gas goes down this time. Should i try using the seafoam through my vacuum lines and the fuel or just the fuel for right now
 
#17 ·
Yea i might use some more and video tape it to see if i can pin point where the smoke is comin from. Do these cars have vacuum lines that go to the tranny i know old muscle cars did and i would imagine these would too but just wanted to ask since i saw smoke rising from the downpipe around the tranny
 
#20 ·
You don't have an EGR. An airpump, yes... but no EGR.

If your Airpump was taking a dive, you would have a couple codes.

FWIW, that area may not smoke anymore. It did it ONCE years ago on my 07 and it never did it again each time I did a treatment.
 
#21 ·
Well ive pretty much worn myself out over this so i just took it to the dealership today and hopefully ill get some answers from there. I told them to just find out the problem and then show me the problem and ill decide what i want to do so i guess ill see what happens
 
#22 ·
Well the dealership pretty much ran into the same problem i ran into did all the test and couldnt find anything wrong so now it comes down to tearing the motor down and see if its internals. The good news is that the dealership is helping me to fight with the insurance about paying for it since its probably caused by the accident. So hopefully ill get some good results out of this i hope. Ill keep you posted on what they find out
 
#23 ·
My WRX leaked smoke from there as well when I sea foamed it. I kinda just blew it off since it was only for a minute or so. Some day I'll get under there and tighten things up/replace gaskets.
When I did mine, I was in talk with Paul as well and he said his did it before as well (like stated above), so its a subie thang I suppose;)
 
#25 ·
Well the update so far is still about the same we had to wait for the insurance to determine if they thought it was accident related and they finally decided today that it is accident related and are allowing the dealership to go ahead and continue. So starting monday they are going to do a compression test and leak down test to determine whether it might be just a valve issue or block issue. Hopefully its just a head issue cause im not sure the insurance will cover a whole new block so i should have a definite answer to my problem by tuesday at the latest.

It definitely helps to have friends in the right places cause im pretty sure if i didnt know the guys as well as i do at my dealership they wouldnt have helped me as much as they did. But yea pretty much what they are speculating is that the impact of the hit of the deer mightve shifted my cam out of line because my timing cover was cracked directly in front of one of my cams so he said its possible it could have had enough pressure to bend the camshaft so once they do the test we will know for sure. As soon as i know anything else ill update on here, thanks again for tryin to help me diagnose as best as we could
 
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