What would cause a lean fuel mixture when cold? I feel a slight hesitation when taking off with the engine cold. It feels very sluggish off the line. I have already replaced the leaking EHA and checked the duty cycle. I measured a reading of 55%. The fuel pressure regulator has also been replaced. How should a new EHA valve be adjusted?

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1989 300CE

55% is showing the system is compensating correctly. Do not adjust it. I would check to make sure no vacuum leaks anywhere which would give the reason why the system is adding the extra fuel.

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I should also add that I checked the duty cycle with the air cleaner off. Does this make a difference to readings? I'm still battling a slight uneven idle. I don't really know what else to check. What is the best way to check for vacuum leaks? The IAC hoses look okay and I've already checked the IAC valve to make sure it was clean. There was no buildup inside and the valve operated freely. I think my next step is to make a code reader and check to see if there are any stored fault codes.

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1989 300CE

Also check the for correct voltage at the 3 pin connector for air flow potentiometer .front side of fuel distributor.
mak