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Re: cold start hesitation and smells rich. (archive)
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Posted by Sheldon on September 27, 2001 at 07:48:33:

In Reply to: Re: cold start hesitation and smells rich. posted by Todd Kenyon on September 26, 2001 at 16:14:57:

Todd, mine does the same thing in the morning. Get it out on the highway and you can feel it hesitating at around 3000rpm. Then about 30 sec. or so it's like the computer flips a switch and instantly it's running like a clock! Any ideas yet?


The one that connects the valve cover to the intake plenum. But it could be caused by an air leak anywhere. I agree however that if it is running rich, then that is not the problem.
What do you mean it smells rich? If you are smelling gasoline, it could be something else. I smelled gas once and it was a loose hose clamp on the end of the fuel rail. Could also be a leaking injector o-ring, etc. Does the exhaust look like it is running rich?

BTW, my problem is not entirely gone, it just improved. I still get some hesitation/stumbling sometimes when engine is cold (instantly, suddenly clears up when temp gauge gets out of blue). Interestingly, it only seems to happen if I start driving immediately after starting. AFAIK, it is normal for the engine to idle at higher rpms (1100) when first started, and then it settles down to 700 or so. If I wait for the computer to lower the RPMs (maybe 30 secs after starting) it runs fine, even tho engine is still cold. See if yours does the same. I would think that this should be a strong clue as to what is causing it, but I haven't heard any good guesses yet.

Todd, which breather hose did you replace?


I have had similar symptoms. It is NOT the cold start injector (which is where Bentley leads you), because there isn't one on this engine. Mine seemed to improve markedly when I replaced the cracked breather hose. I would check for air leaks.


Sorry for the double post. My M5 is hesitant untill completely warm and smells rich. I know what I think it is and have read Benetly, but would like your opinion.





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