Date registered: Dec 2008
Vehicle: '89 S124 200D / '95 C124 E320 dogleg / '95 rod bender
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Quoted: 3 Post(s)
M104 idles low when cold
M104.992 on 1995 E320C (euro) W/O EGR, CC, ASR used to:
-start very quick every time (winter, cold engine), go up to ~1300rpm then ~1100rpm wait there for a while and when engine warmed up drop slowly to warm idle speed without ever stalling or misfiring.
-when driving, and manual transmission (dogleg) was put to neutral and the car was coasting rpm used to drop to ~1300rpm, stay there for a second or two and then slowly drop to idle speed, never misfire or stall; same when changing gears, the drop in rpm was never abrupt;
It developped following habit:
-starts quick with all 6cylinders, runs "straight" (winter, cold engine) but rpm never go up, it remains at ~500-600; if I accelerate sometimes stalls. If I let it be for a minute I can drive the car just fine, it is responsive, pulls like a freight train and everything appears to be just fine;
-rpm drops very fast do warm idle speed between gear changes;
-engine doesn't compensate by going rpm up when AC is ON; at a red light when AC clicks/turns on idle drops to ~500 and sometimes engine stalls; AC goes off - idle speed goes back up a little.
Engine wiring is replaced;
Due to AC on/off I suspect engine coolant temperature sensor doesn't tell ECU engine temperature (the one with 4 pins) but I was wrong many many times before so...
feel free to share if you have an ideea.
P.S. No, I wasn't able to find anything usefull using "search" function...