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impreza classic wrx fail on co fast idle?
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Old 09 Nov 2012, 11:55 AM   #1 (permalink)
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impreza classic wrx fail on co fast idle?

just had mot and failed only on co fast idle reading 0.785%.

i have only just pulled it out of the garage after 2 months and reconnected the battery so done maybe 15 miles until it was tested.

so possibly the ecu has had a chance to set its self up fully. is this common?
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Old 09 Nov 2012, 11:58 AM   #2 (permalink)
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Re: impreza classic wrx fail on co fast idle?

This happened me before. I sat with the car idling waiting for my test for about 10 mins. It failed. The examiner told me to take it a good hard run before the retest and don't sit with it idling. The idea was to get the cat as warm as possible before hand and it passed the 2nd time with no work done. Hope that helps
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Old 09 Nov 2012, 12:01 PM   #3 (permalink)
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Re: impreza classic wrx fail on co fast idle?

i also have a boost controller suppose that will make no difference when not on boost.
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Old 09 Nov 2012, 12:18 PM   #4 (permalink)
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Re: impreza classic wrx fail on co fast idle?

Quote:
Originally Posted by shambles View Post
This happened me before. I sat with the car idling waiting for my test for about 10 mins. It failed. The examiner told me to take it a good hard run before the retest and don't sit with it idling. The idea was to get the cat as warm as possible before hand and it passed the 2nd time with no work done. Hope that helps
I agree, but mine is a sports cat
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Old 09 Nov 2012, 04:27 PM   #5 (permalink)
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Re: impreza classic wrx fail on co fast idle?

I've only the downpipe cat left of the 3 so it prob helped
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Old 11 Nov 2012, 10:17 PM   #6 (permalink)
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Re: impreza classic wrx fail on co fast idle?

Could also be the O2 sensor
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Old 13 Nov 2012, 08:27 AM   #7 (permalink)
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Re: impreza classic wrx fail on co fast idle?

more than likley the cat just isnt enough to pass an MOT, need to put at back on or find a garage thats a bit friendlier lol
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Old 15 Nov 2012, 06:38 PM   #8 (permalink)
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Re: impreza classic wrx fail on co fast idle?

Well, I stuck in some wynns emission reducer and took it for a hard drive for over an hour. They stuck it on and the emissions were nearly double and lamba was now failing. Would it be because it's still kicking out emissions from the additive, I can't make sense of this? Also I noticed they didn't stick the emissions probe all the way in does that help?
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Old 15 Nov 2012, 07:34 PM   #9 (permalink)
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Re: impreza classic wrx fail on co fast idle?

the wynns will work but only after a whole tank full,so get out there n do some driving at a steady speed...
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Old 19 Nov 2012, 01:52 PM   #10 (permalink)
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Re: impreza classic wrx fail on co fast idle?

so not much progress, luckily the mot station havent recorded my retest so i can get back down again before friday and have my retest by then.

There was some improvement but not there yet. i am thinking o2 sensor even tho a cel hasnt thrown up. There are two, why? if i replace one do i just guess?
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Old 20 Nov 2012, 08:17 AM   #11 (permalink)
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Re: impreza classic wrx fail on co fast idle?

where abouts are you?

bets bet would be get it on a dyno, see what it;s doing, it may well be a sensor but you could chase it all over and not find the problem
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Old 20 Nov 2012, 11:17 AM   #12 (permalink)
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Re: impreza classic wrx fail on co fast idle?

never been to a dyno before. im in b'mouth. Does it have to be a dyno as i know there is a guy near me who does diagnostics but he doesent have a dyno.
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Old 20 Nov 2012, 11:34 AM   #13 (permalink)
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Re: impreza classic wrx fail on co fast idle?

mm, not sure whats dowb that way tbh, sure someone on here will though
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Old 21 Nov 2012, 10:18 AM   #14 (permalink)
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Re: impreza classic wrx fail on co fast idle?

good news is ive got it through the emmissions but they have picked up on a nut which is incorrect for trackrod end balljoint as per my new thread, so i have mixed feelings at the moment. happy that the emissions will pass but not happy that i have to source a nut im not sure of to get by tomorrow and im working today and tomorrow

thanks for the responses
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