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Old 09-13-2013, 07:25 PM   #1
White-o
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Default Holy Double Misfire Batman

So I have been having a few problems since I got my wrx around a month ago.
Cylinder 4 was misfiring when I got it, the seller had the coilpack changed, seemed to be fixed, drove it home.
Then about a week later, light came back on.
By this point I had a Cobb SF intake without the box on the car.
I took it in and my mechanic said it needed a new injector and plug on that cylinder as well. Fixed it, car drove great.
I drove the car for about a month with the intake on, and eventually, things got bad. My car eventually went into limp mode and it was recommended that I take the intake off, so I did.

I drove it for about a week with the stock airbox, and now cylinder 4 is misfiring (P0304) and I have P0302 pending.
The car doesn't feel like its misfiring to my very untrained and unprofessional self.
I know that sometimes when I'm idling it tends to shake every now and then.

So with cylinder four having a new injector, new coilpack and a new sparkplug, all thats left in the cylinder is the exhaust valve, correct?

Can anyone provide some insight as to what could be causing this, or is it just not enough info?
I would like to know what the hell I'm doing under the hood of a subaru, but sadly, I don't.

Any help is appreciated.
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Old 09-13-2013, 10:08 PM   #2
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Sounds quite similar to the problem I had. Except I kept getting P0302 with P0304 pending sometimes. That's your drivers side bank. Here's what I did to (so far) fix my problem :

- Cleaned MAF
- Replaced AFR sensor
- Replaced Plugs
- Swtiched coils (misfire didn't follow)

And most importantly, what seemed to make the biggest difference was cleaning the crank sensor! When I was doing my timing belt I found the debris from the wearing out timing belt was all over the sensor!

Others are going to say get a comp/leakdown test, which isn't a bad idea.

Hope this helps
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Old 09-13-2013, 10:26 PM   #3
Blackfin
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When you had the Cobb SF intake on did you also load an OTS Stage 1 + SF tune via a Cobb AP or have it Protuned?

Any time one of these things has misfires I'd suspect a ringland failure. Sad but true. Do a compression test and, if possible, a leakdown test before throwing any more parts or labour at it.
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Old 09-14-2013, 12:29 AM   #4
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Quote:
Originally Posted by Blackfin View Post
When you had the Cobb SF intake on did you also load an OTS Stage 1 + SF tune via a Cobb AP or have it Protuned?

Any time one of these things has misfires I'd suspect a ringland failure. Sad but true. Do a compression test and, if possible, a leakdown test before throwing any more parts or labour at it.

*sigh* Nooooo. I didn't. I read Cobb's marketing thing about that intake not requiring a tune and ate it up.

Ringland failure sounds scary bad lol
The car has been to two different mechanics since I got it and both of them said it definitely doesn't have a compression issue.
Buuuuuuut neither of them actually did a test.
So I'll have that done next.

Thanks for the input.
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Old 09-14-2013, 12:31 AM   #5
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Quote:
Originally Posted by Vrooom_Psh View Post
Sounds quite similar to the problem I had. Except I kept getting P0302 with P0304 pending sometimes. That's your drivers side bank. Here's what I did to (so far) fix my problem :

- Cleaned MAF
- Replaced AFR sensor
- Replaced Plugs
- Swtiched coils (misfire didn't follow)

And most importantly, what seemed to make the biggest difference was cleaning the crank sensor! When I was doing my timing belt I found the debris from the wearing out timing belt was all over the sensor!

Others are going to say get a comp/leakdown test, which isn't a bad idea.

Hope this helps

Thanks!
I'll probably have a compression test done, but I'll try some of the cheaper things you suggested before.
I appreciate the help.
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Old 09-14-2013, 02:55 AM   #6
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[quote=White-o;40592552]*sigh* Nooooo. I didn't. I read Cobb's marketing thing about that intake not requiring a tune and ate it up.

I thought the cobb website specifically said you need to be tuned for their intake? therein lies your problem...running lean fo sho. Take that intake off asap!


edit: nvm, you already took it off! lol

Last edited by dj_quik; 09-14-2013 at 02:57 AM. Reason: add
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Old 09-14-2013, 04:18 AM   #7
White-o
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Another question for you guys: I got a new coilpack, new injector and a new plug, and then ran my car lean because of the intake for about a month. Is that enough time to destroy the brand new parts I just had put on?
Or is it more likely a separate issue?
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Old 09-14-2013, 11:53 AM   #8
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Quote:
Originally Posted by White-o View Post
Another question for you guys: I got a new coilpack, new injector and a new plug, and then ran my car lean because of the intake for about a month. Is that enough time to destroy the brand new parts I just had put on?
Or is it more likely a separate issue?
It could very well do major damage especially if you were hammering on it. Lean conditions are horrible for our engines from what I have read around here. Your new parts are fine more than likely like others said before you could have cracked a ring land. Do as they said and get a compression test
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Old 09-14-2013, 11:31 PM   #9
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Alright thanks for the info. I'm in the Jacksonville area, and I looked around for mechanics. Sounds like the dealership is my best bet, which sucks because I don't have a warranty of any kind ._____.
If anyone knows of a good Subaru mechanic within this area that'd be great.
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Old 09-24-2013, 10:19 PM   #10
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I don't know if anyone still cares, but I have an update on the situation.
Now all of you are probably going to yell at me, because I forgot to have a compression/leak down test done.
I went in to the dealer, handed them the keys and it completely slipped my mind.

Anyway, apparently my ecu hadn't been flashed to the most recent maps that Subaru released awhile ago. Is that something that could cause misfires?

I was at Subaru of Orange Park and my technicians name was Jonathan, btw.
He said he checked for vacuum leaks and I'm fine as far as that goes, and he reflashed the car and everything seems A-Okay.

However, he says if the light comes back and its a misfire, the compression/leakdown test is next.

He charged me $70 to flash it, and I feel alright about that.
My misfire was almost symptomless, other than the cel. I had some slight shuddering at idle, but other than that the car drove fine.
Shudders are a little less apparent now.
I guess I'm kind of having a hard time believing a reflash was all it needed. I was ready for the worst after reading all of these forums.


Anyway, thats where I am now. If things go bad again in the next couple of weeks, I'll make it known.
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Old 09-26-2013, 12:51 PM   #11
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Quote:
Originally Posted by White-o View Post
I don't know if anyone still cares, but I have an update on the situation.
Now all of you are probably going to yell at me, because I forgot to have a compression/leak down test done.
I went in to the dealer, handed them the keys and it completely slipped my mind.

Anyway, apparently my ecu hadn't been flashed to the most recent maps that Subaru released awhile ago. Is that something that could cause misfires?

I was at Subaru of Orange Park and my technicians name was Jonathan, btw.
He said he checked for vacuum leaks and I'm fine as far as that goes, and he reflashed the car and everything seems A-Okay.

However, he says if the light comes back and its a misfire, the compression/leakdown test is next.

He charged me $70 to flash it, and I feel alright about that.
My misfire was almost symptomless, other than the cel. I had some slight shuddering at idle, but other than that the car drove fine.
Shudders are a little less apparent now.
I guess I'm kind of having a hard time believing a reflash was all it needed. I was ready for the worst after reading all of these forums.

Anyway, thats where I am now. If things go bad again in the next couple of weeks, I'll make it known.
Woah woah woah... they charged you for a reflash that is an update to the map by Subaru!? That's just seems like BS. Its like when my moms charger's door locks didn't work right because it needed An"update" that's not anyones problem but the manufacturers... and BTW what year is your WRX?
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Old 09-26-2013, 01:29 PM   #12
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Quote:
Originally Posted by White-o View Post
*sigh* Nooooo. I didn't. I read Cobb's marketing thing about that intake not requiring a tune and ate it up.
Quote:
Originally Posted by dj_quik View Post
I thought the cobb website specifically said you need to be tuned for their intake? therein lies your problem...running lean fo sho. Take that intake off asap!
You need to pay attention to the year of the car...Cobb's 02-07 intake did not require tuning, they specifically designed it to mimic the factory MAF scaling. Cobb's 08+ intake absolutely does require tuning, and you'll most likely blow the engine without it.

White-o has an 07, therefore the Cobb intake didn't need tuning.
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Old 09-26-2013, 04:07 PM   #13
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Is there any oil consumption?

Last edited by Tripintaz; 09-26-2013 at 04:13 PM.
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Old 09-26-2013, 05:59 PM   #14
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Quote:
Originally Posted by Razgeiz View Post
Woah woah woah... they charged you for a reflash that is an update to the map by Subaru!? That's just seems like BS. Its like when my moms charger's door locks didn't work right because it needed An"update" that's not anyones problem but the manufacturers... and BTW what year is your WRX?

Its an 07
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Old 09-26-2013, 06:00 PM   #15
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Quote:
Originally Posted by Tripintaz View Post
Is there any oil consumption?
Not that I'm aware of, but I have only checked it twice so I'll update if there is.
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Old 09-26-2013, 11:00 PM   #16
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Okay I checked the oil and it's at the same level it was a month ago.
It's also very dirty >___>
So there's that.
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Old 10-16-2013, 12:32 AM   #17
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So it's been about a month since I took my car in and yesterday I took a peek with the code reader and I have a pending P0304 :/
Surpriiiiiise. I don't know when but sometime soon I'll be taking the car back in for a compression test.

I guess I'm just a bit confused about the issue because my car isn't exhibiting any symptoms.
The only thing I could think of is that on a cold start, the engine sounds a little strange for the first 15 seconds or so, then fades away. I figured it was just that the oil had drained out of the cylinders and everything was getting lubed up again.

It pulls strong, idles fine, doesn't smoke or make any strange noises, and theres no oil consumption.
And this has been going on for about 2 months or maybe a little longer.
If it was misfiring, wouldn't it have worsened by now?
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Old 10-16-2013, 07:31 AM   #18
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Not exactly... I would play around with it. I just spun a rod bearing the other day 12k miles on the car.
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Old 10-16-2013, 07:57 AM   #19
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you already know what to do next:

compression test.

better yet, leakdown test.
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Old 10-16-2013, 11:06 AM   #20
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That sound on cold start is prob just your TGVs opening.

Running that intake without a tune was pretty dumb, I don't see anywhere on the Cobb site that says you don't need a tune for it. Where did you see that?

Anyways, the intake skews the maf readings and you run lean without a tune. My money is on a cracked land that is on its way out.

Get a leakdown/compression test.



Quote:
Originally Posted by White-o View Post
So it's been about a month since I took my car in and yesterday I took a peek with the code reader and I have a pending P0304 :/
Surpriiiiiise. I don't know when but sometime soon I'll be taking the car back in for a compression test.

I guess I'm just a bit confused about the issue because my car isn't exhibiting any symptoms.
The only thing I could think of is that on a cold start, the engine sounds a little strange for the first 15 seconds or so, then fades away. I figured it was just that the oil had drained out of the cylinders and everything was getting lubed up again.

It pulls strong, idles fine, doesn't smoke or make any strange noises, and theres no oil consumption.
And this has been going on for about 2 months or maybe a little longer.
If it was misfiring, wouldn't it have worsened by now?
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Old 10-16-2013, 11:30 AM   #21
the suicidal eggroll
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Quote:
Originally Posted by nomoreshanks View Post
Running that intake without a tune was pretty dumb, I don't see anywhere on the Cobb site that says you don't need a tune for it. Where did you see that?
Quote:
No Tuning Required
This COBB SF Intake does not require additional tuning once installed. It is designed to work perfectly with the stock MAF sensor. Simply install and go!
http://www.cobbtuning.com/Subaru-SF-...t-p/712100.htm


Once again, there is a difference between the 07- and 08+ models and their intake/tune requirements

Last edited by the suicidal eggroll; 10-16-2013 at 12:06 PM.
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Old 10-16-2013, 11:37 AM   #22
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Well there it is. For some reason I thought he had a GR. I'm stoopid you're smart, I'm ugly you're pretty, etc, etc....

OP, start the car with the oil filler cap off and look for the hurricane of exhaust gases.




Quote:
Originally Posted by the suicidal eggroll View Post
Seriously? Did you not see my post above? Or maybe you just thought I was making **** up.


http://www.cobbtuning.com/Subaru-SF-...t-p/712100.htm


Once again, there is a difference between the 07- and 08+ models and their intake/tune requirements
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Old 10-16-2013, 11:41 AM   #23
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^ dam straight. eggroll is a total babe

Quote:
Originally Posted by ride5000 View Post
leakdown test.
^this

Don't randomly throw money at "repairs" until you actually know what needs replacing.
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Old 10-16-2013, 12:08 PM   #24
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^ dam straight. eggroll is a total babe
hells yea!
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Old 10-17-2013, 09:27 PM   #25
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Thank you guys for backing me up on the intake situation.
Some people on here tend to make assumptions and just try to drill everyone for not being a master mechanic and making mistakes.
This is where people come for help, obviously some people will have more experience than others, but I did my research and I was careful.

Anyway. I brought the car in for the compression/leakdown test today at 10 am, but they spent the entire day working on someone elses car, so I'll have to wait until tomorrow, and I'll have to go without it a whole day -gasp-

I'll let you guys know what the results are, when I hear from them.
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