PeachParts Mercedes-Benz Forum - View Single Post - Should I fix this fast idle or leave it alone?

EricSilver · #4 06-01-2004, 03:53 PM

I have read through all of the posts with "airflow potentiometer" in them. I am not quite getting the feeling that the potentiometer is the cause of my problem. I am, however, thinking I should check for air hose or vacuum leaks.

My main problem is the fast idle. I have also noticed, on reflection, that in the past 8-12 moinths or so the first startup of the day, or secondary startups after the car has been sitting for a long while, seemed to indicate some form of air/fuel starvation. After flooring the accelerator the engine would not respond as quickly as it should -- or would experience a significant lag, especially in very cold weather. The fuel economy guage always seems to react immediately, but the tachometer does not, which suggests an airflow problem, more than fuel flow, if my armchair, "working with insufficient technical knowledge" analysis is correct.

Also, when cruising along at highway speeds, and lifting off the accelerator, there is not the typical drop in engine sound that indicates fuel reduction or cut-off. Instead, it is clear that fuel is still being pumped, and the car does not seem to know my foot is off the accelerator.

My limited knowledge of this still points to the micro switch, but I will check the things that the rest of you recommended.