Rough engine when cold
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Joined: Sep 2004
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From: East Coast
My Ride: 530i 6 speed
We had a discussion here before about rough engine right after start-up when it is below freezing.
My dealer here had told me its normal, but had no explanation.
My dad extracted a useful explanantion from his service advisor in Germany. First of all, the engine runs very rich during the first few minutes. Also, the engine has a separate pump, which ejects additional A/F into the exhaust to help the catalytic converter warm up faster for Euro 4 and the US regulations. This is why the engine runs rough sometimes until the catalyst worms up enough to work.
Hos dealer said that all BMWs have this now, but its most noticable on the V8s.
Just thought some of you might be interested in this.
My dealer here had told me its normal, but had no explanation.
My dad extracted a useful explanantion from his service advisor in Germany. First of all, the engine runs very rich during the first few minutes. Also, the engine has a separate pump, which ejects additional A/F into the exhaust to help the catalytic converter warm up faster for Euro 4 and the US regulations. This is why the engine runs rough sometimes until the catalyst worms up enough to work.
Hos dealer said that all BMWs have this now, but its most noticable on the V8s.
Just thought some of you might be interested in this.
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