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Old 08-09-2025, 04:44 PM   #2
sly
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Drives: 2016 Cosworth 2.2 BRZ
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A couple of possibilities come to mind. Are you sure you have no vacuum leaks? If you PCV hose is loose or one of the hoses on the throttle body are not fully seated, it could cause this. Or it could be the catalyst not heating up or detecting that it's heated up. When starting the engine, you will get an advance on the exhaust valves to warm up the catalytic converter for emissions. If your timing doesn't retard to normal or the 02 sensor is not giving readings, it could stay at fast idle longer trying to warm up the catalyst. You could also have a bad temperature sensor and the ECU thinks the car is colder than it really is.

I assume you have no check engine light? Are there any other symptoms or have you changed anything else on the car, even if it seems inconsequential?
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