Cursed engine light.

[bwanabeet]

I have searched high and low to solve my problem. M272 E30 V6 petrol. Start car idles @ 1000rpm for 30 seconds or more then rough. Osb misfire cylinder 4. If you start to drive before the light comes on no problem runs fine. If you stop in traffic light comes on and rough idle. Clear code restart drive before light comes on. Or use hold and slip in to neutral keep revs to 1000rpm return to drive no problem. Have had 2 mechanics do smoke test. And one complete diagnostic. All it came back with Cylinder 4 misfiring. New plugs and swapped coils. No difference.

 

[BlackC55]

I would be checking compression and timing.

 

[slade1]

Diagnostics using MB STAR before throwing money££££ at it.

 

[pcthrillrider2]

I would be checking compression and timing.

would it not being doing it all the time with compression or timing?

 

[Bellow]

If for no other reason than to eliminate it as a possibility, I'd check out O2 sensor output at the affected speed. Before that I'd check that their heater elements were intact and working as intended.