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vacuum leak would "lean" the mixture....(more) (archive)
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Posted by stephen m. on September 25, 2001 at 10:45:49:

In Reply to: Re: cold start hesitation and smells rich. posted by Todd Kenyon on September 24, 2001 at 13:36:21:

i can understand air leaks giving problems during starting/idling, but an introduced air leak after the AFM would LEAN out the mixture and also cause a high idle (unmetered air entering the intake). if the car smells like it's running rich, i would suspect 2 things first: too much fuel or too little air. i don't have any experience with the S38 engine (mine exp. is with the M20 and M30), but i would check the following "related" items:

TPS
idle bypass valve operation
fuel pressure & pressure regulator
coolant temp. sensor
wiring of the cold starting sensors to the DME

also a good time to check for vacuum leaks. my first guess would be that the coolant temp. sensor or the wiring from this sensor to the DME is giving it false readings. if it reads open, it will simulate a STONE COLD engine.

good luck....

stephen m.
1985 Hartge H5S
dallas, tx


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.



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