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HELP!!misfire after driving 20min from cold
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Old 06 Aug 2009, 11:54 AM   #1 (permalink)
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HELP!!misfire after driving 20min from cold

hi I have a classic impreza wrx 94 import with a misfire after warming it up, and driving for 20 min the misfire is worse between 2000-4000 rpm, idles fine and starts fine, i have replaced plugs and coils , fuel filter also no CEL codes on dash also taken it to garage and had it scanned still no error code has any one got any idea ???????????????
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Old 06 Aug 2009, 08:47 PM   #2 (permalink)
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Re: HELP!!misfire after driving 20min from cold

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Originally Posted by daz23079 View Post
hi I have a classic impreza wrx 94 import with a misfire after warming it up, and driving for 20 min the misfire is worse between 2000-4000 rpm, idles fine and starts fine, i have replaced plugs and coils , fuel filter also no CEL codes on dash also taken it to garage and had it scanned still no error code has any one got any idea ???????????????
Hi,
Where did you take it to be checked?

And what your location?

Suggest you get it to good specialist Subaru garage....

Sorry cant be more help
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Old 10 Aug 2009, 01:45 AM   #3 (permalink)
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Re: HELP!!misfire after driving 20min from cold

Take it to a specialist as Dean said but it could be any
Fuel Pump Faulty
Fuel Lines/Pipes restricted
Worn Leads
Vacuum leak at Trottle body or vacuum leak, air leak
Blocked Fuel injector
Are the plugs gapped right???????
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Old 10 Aug 2009, 01:09 PM   #4 (permalink)
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Re: HELP!!misfire after driving 20min from cold

hi i have tried all of the above except fuel pump / injectors who would be best person to check them and how are they tested?
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Old 10 Aug 2009, 01:11 PM   #5 (permalink)
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Re: HELP!!misfire after driving 20min from cold

it only misfires when warm after 20min driving surely not a blocked injector?
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Old 10 Aug 2009, 01:24 PM   #6 (permalink)
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Re: HELP!!misfire after driving 20min from cold

could be fueling it coughs and splutters revs drop down but you can clear it by going into 5th gear and keeping it below 2000rpm or or put your foot down past 4000rpm and it goes fine its like its getting water in the air filter for eg, but when not driving it and i rev it out of gear theres a true misfire on at least 1 cylinder
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Old 10 Aug 2009, 01:29 PM   #7 (permalink)
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Re: HELP!!misfire after driving 20min from cold

i am trying my mates ecu off a 98 sti in couple of days will it work ok on 93wrx??
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Old 10 Aug 2009, 01:46 PM   #8 (permalink)
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Re: HELP!!misfire after driving 20min from cold

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i am trying my mates ecu off a 98 sti in couple of days will it work ok on 93wrx??
It'll work but probably not the best way to find your problem. Even if you suspect a faulty ecu i don't think this is the best way to go about finding out. The maps are as different as your cars. An STi ecu, esp on a V4/5, is not mapped to run optimally with your engine. You'd be better served finding someone with a car same age/model as yours if possible, and using their ecu.

have you tried simply re-setting the ecu?

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Old 10 Aug 2009, 07:17 PM   #9 (permalink)
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Re: HELP!!misfire after driving 20min from cold

As Wayne said try resetting Ecu not going to harm it or make it worse might be just that you could try a fuel pump from a similiar impreza to rule out the pump
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Last edited by stiimpreza1984; 10 Aug 2009 at 07:19 PM.
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Old 16 Aug 2009, 11:21 AM   #10 (permalink)
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Re: HELP!!misfire after driving 20min from cold

still the same i have reset ecu and tried another one whhat do i try next cant even get it to a dealer
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Old 16 Aug 2009, 04:19 PM   #11 (permalink)
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Re: HELP!!misfire after driving 20min from cold

Quote:
Originally Posted by daz23079 View Post
hi I have a classic impreza wrx 94 import with a misfire after warming it up, and driving for 20 min the misfire is worse between 2000-4000 rpm, idles fine and starts fine, i have replaced plugs and coils , fuel filter also no CEL codes on dash also taken it to garage and had it scanned still no error code has any one got any idea ???????????????
Have you swapped a set of plug leads? They could be breaking down?
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Old 17 Aug 2009, 09:30 AM   #12 (permalink)
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Re: HELP!!misfire after driving 20min from cold

no plug leads individual coil packs. some one told me it could be the ignition amplifier where is this??
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Old 17 Aug 2009, 12:25 PM   #13 (permalink)
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Re: HELP!!misfire after driving 20min from cold

I NEARLY CERTAIN NOW THAT ITS THE IGNITOR AMPLIFIER ITS WIRED TO THE SPEED SENSOR AND COILS WILL EXPLAIN WHY IT MISFIRES WORSE AT CERTAIN SPEED GOT ONE ORDERED FOR TENNER LET YOU KNOW IN COUPLE DAYS
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Old 04 Sep 2009, 02:39 PM   #14 (permalink)
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Re: HELP!!misfire after driving 20min from cold

ok it isnt the ingniter or cam sensor recently been to zen performance they dont know either someone please help what next ????
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Old 04 Sep 2009, 08:03 PM   #15 (permalink)
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Re: HELP!!misfire after driving 20min from cold

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ok it isnt the ingniter or cam sensor recently been to zen performance they dont know either someone please help what next ????
OK could try the HT lead individually the insulators themselfs that go onto plug might be the contact might be loose make sure it a snug fit to spark plug, also the spark plugs are right for the car and gapped right? did you try fuel pump???? what about a faulty fuel regulator just a thought
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