P0304 Misfire in Cylinder 4

Blownbyyou

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So last night I was driving home and unfortunately my 2011 SHO decided to crap the bed. I was wondering if anyone has had this issue before...

On the expressway i gave it a little gas (not past half throttle) and saw check engine light start blinking, then notice a definite miss fire. I pulled over and ran the code and got the above code.

I had it towed to an independent shop and they think its an injector and I am thinking I agree because i noticed last night that the afr on one bank was 14.xx and the other bank was 9.xx.

They don't really seem to want to do the job, was wondering if anyone has done it or if its another issue?


P.s. the car has a unleashed tune on it with a 3 bar map (running fine before that).
 

lastls1

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Looks like the injector replacement is just over 4 hours, and looking at the procedure a decent amount has to come off to do it. Alone with quite a few warnings and bolded items saying if things are not routed in a certain way or removed a certain way further damage may occur.

They may not want to chance it idk
 

rdsnake

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I'm not saying an injector isn't the problem but it's more common for spark related problems with misfires.
 

Blownbyyou

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I'm not saying an injector isn't the problem but it's more common for spark related problems with misfires.
I agree, but doesn't the afr on the one bank of 9.xx illustrate that one injector probably isn't firing?
 

Blownbyyou

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Does anyone have any recommended shops in the southwest burbs?
 

Ryan02Stang

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Had the exact problem last week on my 2012 MKS (Unleashed tune + 3 bar). I flashed back to stock figuring if it happens again I'll just take it in for warranty, but the issue hasn't repeated. Mine happened about a mile from my house so I limped it home.

Torque app pull below...

 

1quick

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I'd start with checking the plugs, I've had misfires on a bunch of cars it's always been a plug a wire or a coil pack, or a piston laying in my oil pan lol
 

bikrboy128

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pull coil 4 and swap with another cylinder, clear codes and drive. fords are common for ignition coil failures, i know ecoboost engines can chew up spark plugs too. maybe check cylinder 4 plug while you're in there.

these days, injectors very rarely fail. cylinder 4 on the SHO is the front bank (radiator side) first coil on the passenger side. super easy to get at/swap.
 

blakbearddelite

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My 2V Mustang went through some coils. I had a really bad misfire and there was nothing wrong with the plugs. We swapped out all eight coils and never had a problem again. Though if I had the time, I would have just preferred to replace the bad ones. But it sounded like a real pain in the ass to swap them one by one and figure out which one(s) were bad.
 

Blownbyyou

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Soooo i just went to pick it up from the mechanic that said he couldn't do it, as i was driving to another mechanic the issue went away completely.. put twenty miles on it and no issue...

WTF
 

Ryan02Stang

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Soooo i just went to pick it up from the mechanic that said he couldn't do it, as i was driving to another mechanic the issue went away completely.. put twenty miles on it and no issue...

WTF
I'm 150 miles since it happened...no sign again. Curious...did you flash back to stock, or leave your tune flashed?
 

Blownbyyou

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I did pull the plug and it was black and wet....weird.
 

Ryan02Stang

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I had a faint smell of gasoline when it happened to me...making me think there was no spark, but I haven't had a chance to check my plugs yet.
 

SloTBSS

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Earlier shos are common for the injectors to stay stuck open. Well I shouldnt say common, but have done a handful.
 

Blownbyyou

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Do they fix themselves or do they need to be replaced
 

RedBeard

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If AFR on one bank is 9.X that'd be really rich meaning most likely an ignition issue that isn't burning the fuel causing the really rich AFR.
 

SloTBSS

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I honestly couldn't tell you if they fix themselves. I replace them just because I've had a couple come in and while your pulling codes, the cylinder will be filling with fuel and you'll see it come out of the exhaust.
 

Blownbyyou

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I honestly couldn't tell you if they fix themselves. I replace them just because I've had a couple come in and while your pulling codes, the cylinder will be filling with fuel and you'll see it come out of the exhaust.


Are you at a dealer? I recently read they have a 70k mile warranty /7 year warranty on the injectors....

I honestly think that is my problem because I moved coil and plug from 4 hole to 5 hole and the problem stayed In hole 4
 

SloTBSS

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Are you at a dealer? I recently read they have a 70k mile warranty /7 year warranty on the injectors....

I honestly think that is my problem because I moved coil and plug from 4 hole to 5 hole and the problem stayed In hole 4
Yeah and I could double check if theres additional warranty coverage for the injectors tomorrow for you.
 

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