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Misfire Problem.
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Old 20 Dec 2009, 12:39 PM   #1 (permalink)
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Exclamation Misfire Problem.

Hey, i have a misfire problem on my 2000 uk turbo spec impreza. Its only at mid throttle, you can drive the car fine only using an inch of the pedal, and then when its over 5000 revs its fine as well. I have interogated the ECU, and the fault codes are 22 (Knock Sensor) and 23 (Mass Air Flow Sensor Circuit). Are the fault symptoms in check with the fault codes? I really dont want to fork out for a MAF if its not that! I have tried cleaning the MAF, it made no difference. Please Help!
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Old 20 Dec 2009, 01:11 PM   #2 (permalink)
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Re: Misfire Problem.

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Originally Posted by 6580durra View Post
Hey, i have a misfire problem on my 2000 uk turbo spec impreza. Its only at mid throttle, you can drive the car fine only using an inch of the pedal, and then when its over 5000 revs its fine as well. I have interogated the ECU, and the fault codes are 22 (Knock Sensor) and 23 (Mass Air Flow Sensor Circuit). Are the fault symptoms in check with the fault codes? I really dont want to fork out for a MAF if its not that! I have tried cleaning the MAF, it made no difference. Please Help!
Doesn't sound like the MAF to me. If it was the MAF you would likely have issues at idle and low revs.

First thing I would check would be coil pack. Then check leads and plugs and make sure plugs are gapped correctly.
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Old 21 Dec 2009, 09:16 AM   #3 (permalink)
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Re: Misfire Problem.

could well be the plug gap is too large and your blowing the spark out..
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Old 21 Dec 2009, 01:53 PM   #4 (permalink)
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Re: Misfire Problem.

If it was a plug or coil pack would it read a fault code relating to which cylinder the mis-fire was occurring ?
I had this on MY03 STI and it was reading cylinder No2 mis-fire. I just swapped the coil packs around to see if the mis-fire moved too.
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Old 24 Dec 2009, 01:50 PM   #5 (permalink)
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Re: Misfire Problem.

So the general consensus is a plug/coil pack problem? Would the coil pack not bring up a fault code? Does anyone know if it is possible to convert the single coil pack system into the Individual coil packs like the newer EJ20's?
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Old 24 Dec 2009, 03:54 PM   #6 (permalink)
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Re: Misfire Problem.

Right ... I just thought I'd give resetting the ECU a try, now there are no fault codes (maybe because i haven't driven it long enough?). Doing this has improved the miss firing drastically, now it doesnít do it at all when driving sensibly, it only splutters once or twice in first, second and third when driving hard. I havenít checked the plugs yet, Iím just going to replace them next year. What should the gap be anyway?
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Old 24 Dec 2009, 04:53 PM   #7 (permalink)
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Re: Misfire Problem.

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What should the gap be anyway?
0.7mm should be fine.
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