C124 cutting out
 

The car's engine cuts out sometimes;
Most of the time it occurs once the engine is warm and always at low revs/ idling speed. Typically when you slow down (no foot on accelerator or brakes) when taking a highway exit and just coasting to a stop. As the revs go lower it just cuts out suddenly. It immediately starts again though.
It is not as if the engine is starved of fuel - its a sudden cut out as switched off.
Car is a 1240502B076917 1990 300CE (South Africa) and to date the local MB agents have ruled out the following;
distributor cap and rotor
air slide
fuel pump relay
ECU
voltage protection relay
ignitor box

Any advise is appreciated.

Thanks
FM

Perhaps your wiring harness is having issues? See:
PeachPartsWiki: W124 Engine Wiring Harness Replacement

EDIT: Just saw 300CE which would have been m103 not m104.


Have you tried OVP relay? Spark Plug Wires? I had this same problem happen in my 190E. I had to keep my foot on the gas and keep the revs up to keep the engine from stalling. Turned out the OVP was bad at the bottom of it. I resoldered it and replaced my spark plug wires, I later found one of the connections had gone.

Its the M103 and yes the OVP was replaced and spark wires tested (not replaced).
The M104s seem to have the wiring harness issues - not the M103's or am I mistaken?

I've not heard of m103's having the harness issues. M104 YES.

Check your duty cycle at the X11 port. Put black probe in pin 2, and positive in pin 3. Observe duty cycle % (or voltage if you dont have meter with duty cycle%).

If this value is a fixed number, then you have an issue on one of the CIS components. If the voltage/percentage is changing rapidly, CIS components are normal. Then try adjusting your lambda tower so that duty cycle hits about 40-50%

Up until recently my lambda tower was not set correctly and my m103 would stall out on the first start.