Car idles weird - Subaru WRX Forum
 
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#1 Old 11-17-2011, 12:13 PM
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Car idles weird

My buddy's 2006 sti when idling you can hear the cars tons drop then rise to normal idle then drop then rise again. Any ideas of what this could be there is cai turboback exhaust and has been tuned. This was all on the car when he bought it.
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#2 Old 11-17-2011, 12:22 PM
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Hmm, I would try to track the history down of when this started. So many things cause behavior like this, dirty/bad sensors, vacuum leak, dirty/sticking injector (although this would usually cause 'rough' idle as well), how long has it done this?
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#3 Old 11-17-2011, 12:39 PM
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Yes, what troubleshooting has been done already? Idle issues can range from being ignition related all the way to bad compression.

How many miles?
When was the last time the plugs were replaced?

- Sandra
2007 WRX TR | Stage 2 | PAR Gearset (Built by AndrewTech)
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#4 Old 11-17-2011, 02:08 PM
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Not sure on plugs injectors were just cleaned and tested Been doing it since he bought it couple months ago noticed it more since it got colder. It was tuned in 96 degree weather. Not any other troubleshooting done was just trying to figure out what it could be I was thinking vac line
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#5 Old 11-17-2011, 02:11 PM
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Boost leak test would tell ya real quick if there was a leak in the vac line

- Sandra
2007 WRX TR | Stage 2 | PAR Gearset (Built by AndrewTech)
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#6 Old 11-17-2011, 02:15 PM
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^This. Or a smoke test

Paul
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#7 Old 11-17-2011, 02:25 PM
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Although, with my 07 I had a boost leak (when I installed too large ID vac lines to my BCS) and the car still idled fine. I just ran pig rich and couldn't boost past 7psi .

- Sandra
2007 WRX TR | Stage 2 | PAR Gearset (Built by AndrewTech)
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#8 Old 11-17-2011, 06:51 PM
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Come to think of it I doubt it's vac considering it's tuned and hitting 23 psi
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#9 Old 11-18-2011, 05:56 AM
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OP... Tell you what, clean up your first post and we can give a bit better feedback.

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#10 Old 11-18-2011, 09:13 AM
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A small vacuum leak would be nothing for the boost controller to compensate for, and if it's pre turbo it wouldn't matter anyway, but could definitely make a difference at idle. I would start with checking all the vacuum hoses, boost controller, air temp, bov/bpv etc, and then move to leaks in the intake post turbo, intercooler piping, bov cracking open if its not recirc, and then move to sensors..just way too many things for us to guess at really. If it was bad enough plugs, "usually" it would throw a cel, from rough in cylinder x.
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#11 Old 11-18-2011, 03:11 PM
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Clean the MAF sensor, also put the stock air intake on it.

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#12 Old 11-18-2011, 09:04 PM
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Thank you for the help everyone I was just trying to get an idea of what to check. Thank you for all tour help
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