Quote:
Originally Posted by Dellpc
Could you explain a little bit more about how blowing air to exhaust change the way engine is running during the cold start? I would assume that the oxygen sensors are not reading during the cold start anyway, therefore, only increased/decreased backpressure could somehow change engine behavior.
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The misfire is there until the engine is in closed loop operation. The secondary air pump causes closed loop operation to start sooner by increasing the O2 which results in faster heating of the O2 sensor and cats. If it is the pump you should hear a whirring noise or grinding type noise for a short period of time after a cold start. It could be other components of the system rather than pump itself. Suggest you check for error codes.
BMW Secondary Air System Fault Code Diagnosing How To DIY OBD-II | Bavarian Autosport Blog
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Last edited by bcredliner; 12-29-2016 at 02:46 PM.
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