1993 525i M50 Petrol engine strange behaviour

[Ferret]

But when pushing throttle I felt like slowered reaction between throttle move and engine acceleration. A hesitation. Like mixture was for a moment too lean. But no more intake shooting. I'll try to borrow a MAF from junkyard and try it instead of mine. Any other clues what might be causing this? Thanks again, guys.

That may well be because you've been fiddling around with the MAF unplugged, etc. Give it a few days of running to see if it comes back... Also double check all your air hoses to ensure there's no leaks.

[BillionPa]

pull the ECU to clear the map, its gonna be all screwed up because of the plugs.

[Daddario]

Hello again.

So, yesterday when I got my MAF out I noticed, the hot wire inside is broken! How could I overlooked it?! I plugged in the used one from junkyard for 100$. Car runs like never before. Still, after two minutes after cold start I feel the mixture is somehow lean. When engine gets bit warmed up everything is in order. Then I read your posts about disconnecting harness connector from ECU. Should I do this? In case O2 is faulty, will I be able to drive the car, cause I really need it now and budget to buy new O2 is sparse. And another question... Isn't enough to unplug the battery instead of ECU? Thanks a lot, guys for your input.


MAF's guts.


Oily plug.


Rusty plug.

[Morgenster]

Is it just the lighting in this picture or are there no electrodes?
If that was in your engine, no wonder you were having backfires.
Unplugging the battery should do it if you do it long enough.
And before pointing fingers at the O2: try looking for intake leaks behind the MAF.

[BillionPa]

unplugging the battery has the nice side effect of erasing the transmission control unit memory, the radio presets, the obc time, the dash memory, and probably something i forget. its also easier to unplug the DME harness.

resetting the lambda map should fix the lean warm up, but the o2 sensors could be fouled, and will get iffy again. either way, your car will run better with a reset.

i am extremely curious as to why there was no MAF failure check engine code, as lack of continuity seems like a hell of a good reason to throw one!

also, change your oil, its probably diluted with fuel and not protecting your engine anymore.