1995 W124 (S124) E200 M111 - Starts up fine but dies after ~10 seconds (Troubleshooting)
Hi everyone,
I'm troubleshooting an issue on my 1995 W124 Estate (S124 E220) with the 2.2L M111 engine and 722.4 automatic transmission.
The Symptom:
The car starts up fine immediately, but after running for about 10 seconds, it cuts out and stalls completely.
What has been inspected and done so far:
OVP Relay & Fuel Delivery: Inspected and resoldered the OVP (overvoltage protection) relay, and checked the fuel pump operation.
Intake Manifold & Vacuum Refresh: Removed the intake manifold to unclog the brass vacuum nozzle underneath. Also replaced the intake manifold gasket and all fuel injector O-rings with fresh seals to eliminate vacuum/air leaks.
Despite this, the engine still consistently dies roughly 10 seconds after starting.
My questions for the community:
1. What typically triggers an M111 to cut out after 10–15 seconds? Could this be related to the fuel pump relay losing the run signal after the initial prime/crank cycle?
2. Could it be a failing Crankshaft Position Sensor (CPS), MAF/air mass sensor, or throttle body actuator issue?
3. Are there any specific wiring harness degradation spots (eco-junk harness era) or hidden vacuum check valves that I should test next?
Any guidance, diagnostic steps, or similar troubleshooting experiences would be greatly appreciated!
Thanks in advance!