m20 not running well

[uflnuceng]

Awesome :D

[r0l4n]

It failed again yesterday night, 4th gear at 5000 rpms :( I received another AFM today, let's try it.

[r0l4n]

Failed too at the same rpm range The car is smooth now at low rpm, so I'll keep this AFM on. But once I know it's not an AFM problem, does anybody have a far idea of what else could be causing those failures? The engine suddenly stops pulling and starts again, and 2 or 3 seconds later again. Something about plug wires, rotor... I don't know Thanks a lot.

[arsevader]

Failed too at the same rpm range The car is smooth now at low rpm, so I'll keep this AFM on. But once I know it's not an AFM problem, does anybody have a far idea of what else could be causing those failures? The engine suddenly stops pulling and starts again, and 2 or 3 seconds later again. Something about plug wires, rotor... I don't know Thanks a lot.

My old 325e had a hesitation at that rpm caused by a dud O2 sensor, try dissconnecting the sensor to see if the problem goes away.

James

[uflnuceng]

Not that my recommendations are probably carring much weight with you right now, but i think this is going to be a hell of a search.

* Spark plugs: how do they look? White usually means lean? If they are fowled with oil they will look like that have been dipped in tar?
* Wires: when you flex them or squeeze them, do they make krinkle sounds, like they are brittle?
* Take the rotor off and see how the electrodes look.
* Inspect all of your vacuum and air hoses for cracks.
* I don't know if the fuel pump is a failure issue on the M20s, but it sounds like it could have something to do with that.
* leak down and compression test on the engine?

Unless someone around here has had exactly your issue you are going to have to do a lot of tearing apart and diagnosing to find the problem.

[r0l4n]

arsevader: I think the o2 sensor is ignored at WOT, maybe I'm wrong.

uflnuceng: i'll revise the points you talk about the next days, thanks for your write up :?