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Old 08-21-2007, 11:54 AM   #1
capitalj4
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Unhappy coil question

hey everyone! i have a 2003 wrx with 60,000 miles. hks downpipe, magnaflow catback, cobb up pipe with cell fix. and a cobb ap.

i have been having some problems with middfires. first it was p0302, p0304. then it was p0301,p0302,p0304. now its on all 4 cylinders.

the car missfires at idle and slightly above, then goes away when there is load on the motor. also the car does not missfire when the motor is cold

my plugs are only about 3 months old. and i was woundering if i could bench test my coils some how?

thank-you for any help givin!
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Old 08-21-2007, 12:45 PM   #2
Rudywrx04
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Quote:
Originally Posted by capitalj4 View Post
hey everyone! i have a 2003 wrx with 60,000 miles. hks downpipe, magnaflow catback, cobb up pipe with cell fix. and a cobb ap.

i have been having some problems with middfires. first it was p0302, p0304. then it was p0301,p0302,p0304. now its on all 4 cylinders.

the car missfires at idle and slightly above, then goes away when there is load on the motor. also the car does not missfire when the motor is cold

my plugs are only about 3 months old. and i was woundering if i could bench test my coils some how?

thank-you for any help givin!
This seems to be a fairly common problem. Usually when you go with a larger downpipe its usually without a heat shield. I have a 2004 stage 2 and the under the hood temps fried 3 coils. I just replaced all 4 and everything works great. I got a cusco heat shield and wrapped the downpipe and no problems again so far.
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Old 08-21-2007, 08:29 PM   #3
BradsWRX
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Just find an old plug that you know is good, plug it into the coil and ground it to the motor and see if its firing, unplug each coil while running until you find your dead spot, or if you can weld you can buy a plug and tack weld an alligator clip to the side then just clip it to a ground source (helps with the getting shocked part).
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Old 08-21-2007, 08:31 PM   #4
BradsWRX
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Really sounds like a bad coil to me, What happens is when they get hot they internally seperate.
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Old 08-22-2007, 12:57 AM   #5
capitalj4
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ok thanks! ill try all that! but i dosconnected th coils packs once before seperatly, and none of them changed the the idle speed or made the motor want to run rougher, everything seemed to stay the same. and that makes no sense?? this is so confusing.

i have wraped my dp, i will get a heat shield asap!

also if i do get new coils, do i need them off a nother 2003 wrx? or are ann coils from wrx's to sti's interchangeable?

Thank-you everyone so far!
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Old 08-22-2007, 11:57 AM   #6
Jon [in CT]
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Quote:
Originally Posted by Rudywrx04 View Post
This seems to be a fairly common problem. Usually when you go with a larger downpipe its usually without a heat shield. I have a 2004 stage 2 and the under the hood temps fried 3 coils. I just replaced all 4 and everything works great. I got a cusco heat shield and wrapped the downpipe and no problems again so far.
The lack of a heatshield would have little affect on #2 or #4. Mutliple premature coil failures are frequently (but not always) associated with a UTEC piggyback.
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Old 08-22-2007, 12:28 PM   #7
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You can check the resistance of the coils with a good Ohm meter. Just compare the four. If you find there is one out of line with the others it might be the bad one. However... I doubt your coils are bad. The older black coils like you should have are way better then the newer grey coils. Jon is right on the utec eating coils. The old utec firmware munched hundreds like pacman to the dots. The later revs of firmware do not have this issue.

Things that generaly cause misfires on bugeye subarus:

1. Wrong, worn or incorrect gapped spark plugs. You should run only NGK stock range plugs gapped to 028.

2. Clogged injectors. Have the injectors cleaned or at least run several bottles of a good injector cleaner through the engine.

3. Carbon build up on motor. Real common on EJ205's. Get some BG Chemtool, GM top end cleaner or other type of carbon remover. GM top end cleaner seems to work really well.

4. Oil or dirt build up on MAF sensor. This causes an incorrect load reading which make for AFR corrections out of line. Misfires can result. Remove the sensor, place in plastic bag. Spray out with NON clorinated brake cleaner. Let it sit on table for 30 minutes and install.

4. Vacuum leak. Check the turbo inlet pipe where it connects to the turbo. This pipe is famous for ripping and causing a huge preturbo leak.

5. CLean the ground cables that run to the intake manifold. These are sensor grounds and must be kept clean.



Clark
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Old 08-22-2007, 08:27 PM   #8
capitalj4
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ok thanjs a lot every! and azscoobie! on your list i still have to do the ground cables, and the clogged injectors, and the plugs. ill do that tonight, or tomorrow.

but on a quick update:

--- i listened closer and the car does miss fire at lide, (hot and cold engine) also if i rev the motor up to about 2000 rpms or so, you can clearly hear the car missfiring, but its not a constant missfire. as if the miss fire is jumping from cylinder to cylinder (it sounds fine then you hear it stumble, then its fine for a few seconds and repeat).

--- at idle at a red light the car will shake around a bit, you can feel the motor struggling. then its fine for a few seconds. then it starts up again.

--- under normal driving conditions you dont hear the missfire, and its very hard to feel.

---under heave load, the motor will hesitate/sputter/ then it takes off fine, then it starts back again. as if the car isnt middfiring all the time.

--- this last part may have nothing to do with anything. but (while the air conditioning is on, its very hard to tell if the car is missfiring, or if its just in my head?)

thank-you very much everyone! i greatly appriciate all the help so far.

anymore ideas with the new update?
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Old 08-23-2007, 02:53 AM   #9
-WickedRex-
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Default coils

okada projects plasma coils are the best upgrade for coils or spec c coils ver. 7 or 8 i believe.
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Old 08-24-2007, 01:23 AM   #10
capitalj4
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so where could i get these okada projects plasma coils or spec c coils ver. 7 or 8? i searched. but couldnt really find anything. ill keep trying tho!

Thank-you!
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Old 08-24-2007, 11:26 AM   #11
Rudywrx04
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Quote:
Originally Posted by Jon [in CT] View Post
The lack of a heatshield would have little affect on #2 or #4. Mutliple premature coil failures are frequently (but not always) associated with a UTEC piggyback.
Im interested by this as I do have a UTEC. What with the UTEC causes this problem? Is there a fix?
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Old 08-24-2007, 12:17 PM   #12
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Quote:
Originally Posted by Rudywrx04 View Post
Im interested by this as I do have a UTEC. What with the UTEC causes this problem? Is there a fix?
FWIW, my issue with this, when running a UTEC, was only at idle/really low rpm. This was before the UTEC could compensate for injector dead time. Especially bad on humid days.
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Old 08-24-2007, 10:15 PM   #13
ravenhil
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How long are the stock coils expected to last anyway? Or mileage for that matter? Mine's 5 years old and mileage is like 100 000 miles.
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