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Old 10-17-2012, 10:46 PM   #1
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
Location: Canada
2003 WRX w STI V8

Default Cold start idle issues with new o2, No cold start idle issue without o2.

I put this in the tuning section but guess its more appropriate here.


During a cold start with no o2 sensor plugged in the car fires up at 1500rpm then makes its way down to 900rpm. Perfect, no issues!

Now we do it again but this time install the o2 sensor. Fires up at 1500rpm then makes it way lower then jumps up, goes down, jumps up, rinse and repeat. When the rpms go up the car leans out, when the rpms drop the car richens. It does this until the car is warm.

Once the car is warm you can start her up and it idles perfectly.

o2 sensor is brand new. I was running without an o2 for 2 weeks until I received it today. Once I put it in/cleaned the codes the car would idle as described above. Also to note, this happened with the previous o2 until it crapped out on me.

Can this be pointing to the MAF?
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Last edited by OC_Nooby; 10-18-2012 at 07:01 PM.
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