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Old 03-02-2010, 12:22 PM   #1
txl146
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Chapter/Region: Tri-State
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02 WRX VF34
Junior Tuned 301whp

Default Rough idle - cold start up

Yes, I did search, but couldn't find anything useful. Here is a list of things I have done, but did not help.

1. IACV - disassembled completely and thoroughly cleaned
2. MAF sensor - cleaned
3. Checked vacuum lines and hoses

Other than checking for plugs, coil packs (will check tonight), what else are there to check? This is very strange as rough idle is confined to cold start up. Once warmed up, car drives perfectly normal.

Any other suggestion?
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Old 03-02-2010, 12:52 PM   #2
NoHandsNurse
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I have a similar problem and responded in the same ways you did. On some of these rough idles after first starting my car I notice that the ecu retards timing till after the idle smoothes out. It is not a common occurance but it has happened more than once. I think the idle could possibly be related to timing tensioner or belt as I have read of some rough start/idle issues related to a tensioner going out. Probably going to take of the cover and check for play in the tensioner/belt to see if it could be the culprit.
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Old 03-02-2010, 01:31 PM   #3
txl146
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Junior Tuned 301whp

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I recently had timing belt work done where everything including pulleys and tensioner got replaced. Plugs were recently replaced as well prior to getting a tune a month ago.
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Old 03-02-2010, 04:15 PM   #4
Haelan
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Pressure test the air intake and rule out any leaks. Visual inspection is great if the leak is obvious, but more commonly the leak is hidden out of view.
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Old 03-02-2010, 05:02 PM   #5
txl146
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Junior Tuned 301whp

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Leak check was OK when I got my car tuned unless new leak developed in the last 3-4 weeks. Since problem is seen only when car is COLD (start up), I highly doubt there is leak in the air intake. At any rate, I will double check again.
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Old 03-02-2010, 06:23 PM   #6
ocelot21
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WRB vf22'd

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i had a tgv motor go out on me. It caused the car to act like it had tgv deletes, and had a really odd idle. I don't know if this is similar to what youre experiencing, but its something to think about.
Grimmspeed sells em for dirt cheap.
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Old 03-03-2010, 04:03 PM   #7
ride4life00
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i had a similar issue where as my 05 wrx wagon would idle rough either on a cold start, or seldom @ a red light, i had recently replaced the belts, flushed my power steering line/res (just because it was time & the smoother it runs the less it pulls from your engine), re-adjusted belts, checked timing, & haven't had a problem since....
Good luck
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Old 03-03-2010, 04:41 PM   #8
PSolbergfan
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Your valves may need to be adjusted. The lash that is. I saw you have a 02 WRX, tuned with a VF34. I'd suspect the valve lash.
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Old 03-03-2010, 07:51 PM   #9
Tut4u2
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Fatten up the fuel trim at cold start and see if that fixes it. What are your trims like?
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Old 03-03-2010, 08:04 PM   #10
elevenpoint7five
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If you post a log of the rough idle we might be able to help better

Andy
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Old 03-03-2010, 11:09 PM   #11
txl146
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Junior Tuned 301whp

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Here is an update.

Cleaned the MAF sensor again using MAF cleaner (2nd time). This time, I spent more time and soaked the sensor in the cleaner for 20 min.

Problem fixed....
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