Why is my m50 running pig rich

[slammin.e28]

Car can't make calculations. Rather than go lean (and EXPLODEEEEBOOMMM!), it protects itself and goes rich. Need dat o2 sensor. Rich > lean. It's a smart cookie.

[lolcantturn]

You need an O2 sensor dude. M50 runs like utter shit without it anyway

[bimmerteck]

I don't have an o2 sensor

^ This would be my first guess.

[ScHpAnKy]

Confused, my m50nv is running so rich it's shooting flames...
granted, I don't have an o2 sensor but neither have my last couple cars and that was never an issue...


Cool temp sensor and sender are brand new, CPS is brand new, running 413 ECU since my 402 died. Harness checks out fine so I think it's a sensor somewhere, or DME? The only things that aren't new on the engine are the cam sensor, ICV, headgasket, and IAT... are any of those suspects?