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Old 03-05-2008, 06:50 PM   #1
Susie's Suby
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Join Date: Jul 2002
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Location: In the #24 Chevy--I mean Subie
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01 Impreza RS 2.5
Blew-ridge Pearl

Default Help me!!!

I am ready to drive this car off a cliff.
We have an 01 2.5RS, the engine started to have a bad misfire. I replaced plugs and wires, no improvement. Took it to a dealer, they found a cracked y-pipe, also showed codes for misfires on 2,3,4 cyls, cat sysytem efficiency below threshold (p0420), evap emission control system malfunction (p0440),
and evap system vent control low imput. We replaced the y-pipe and cats, now runs even worse. If revs go below 4000, the engine just about dies. While we were waiting for cats to come in, the shop put a straight pipe in, and the car ran fine. They installed the cats today and its bad again. Does anyone have any ideas why this would happen?
Mike
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Old 03-05-2008, 07:23 PM   #2
novacivic
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maybe o2 sensor or bad coil
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Old 03-05-2008, 08:06 PM   #3
Susie's Suby
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Blew-ridge Pearl

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Is there any way to test the coils? and if they were bad, would they still work at high rpm's?
Mike
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Old 03-05-2008, 08:24 PM   #4
Subyroo2.5
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Do you have a digital multimeter? you can use that to check the resistance of the coils but I dont know what the spec is............and no the higher the rpm the more load is put on the ignition system...
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Old 03-05-2008, 08:56 PM   #5
subtoy
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Try spraying some water on the coil,if it sparks it is no good.
Does it run bad all the time?
Could have jumped time if it runs rough all the time.
May have to do a leakdown test just to make sure cylinders are ok.
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Old 03-05-2008, 09:22 PM   #6
Susie's Suby
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01 Impreza RS 2.5
Blew-ridge Pearl

Default

It runs strong over 4000 rpm's, but wants to die below, while you are driving. It will idle about 10-15 seconds smoothly, the drop to below 500 rpms and shake. If you give it the gas it will pick up revs immediately, but then repeat the low idling and shaking. It is very frustrating.
Mike
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Old 03-06-2008, 08:59 AM   #7
bobko
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Quote:
Originally Posted by Susie's Suby View Post
It runs strong over 4000 rpm's, but wants to die below, while you are driving. It will idle about 10-15 seconds smoothly, the drop to below 500 rpms and shake. If you give it the gas it will pick up revs immediately, but then repeat the low idling and shaking. It is very frustrating.
Mike
Could be a vacuum leak. If you can, try to listen under the hood while the engine is running -- a vacuum leak can often be heard as a loud hissing noise. An engine with a vacuum leak (cracked rubber hose, usually) will show exactly the symptoms you describe: smooth and normal at high revs, but stumbles and dies at idle.

You could also check the idle air control valve (IACV or IAV, depending on who you talk to). However, a vacuum leak is the first thing I'd look for and it's easy/cheap to fix.

--Bob
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Old 03-06-2008, 12:44 PM   #8
Susie's Suby
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Member#: 21370
Join Date: Jul 2002
Chapter/Region: MAIC
Location: In the #24 Chevy--I mean Subie
Vehicle:
01 Impreza RS 2.5
Blew-ridge Pearl

Default

Quote:
Originally Posted by bobko View Post
Could be a vacuum leak. If you can, try to listen under the hood while the engine is running -- a vacuum leak can often be heard as a loud hissing noise. An engine with a vacuum leak (cracked rubber hose, usually) will show exactly the symptoms you describe: smooth and normal at high revs, but stumbles and dies at idle.

You could also check the idle air control valve (IACV or IAV, depending on who you talk to). However, a vacuum leak is the first thing I'd look for and it's easy/cheap to fix.

--Bob
Thanks--there *is* a hiss... Are there hoses that aren't in plain sight to check? I sprayed carb cleaner on the ones I could see, but they seemed okay.
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Old 03-06-2008, 05:33 PM   #9
yarrgh
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on an 01 RS...hmm....there is a vacuum hose to the pressure regulator and cruise control on the passenger side pointing towards the rear. there is the brake booster on the driver side, also pointing to the rear. you can also try looking at the manifold gaskets for the intake, TB, MAP....ummm. IACV too. maybe check the bolt tightness on some things. also check the hose for the gas tank pressure relief, it's right behind the alternator/PS pump. may have a purple electrical connector.
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