Engine breaking up at 2700-3000 rpms

[alpineE30]

Yeah I bought another bmw a while ago its a 86 325es automatic.Now when I hold the accelerator pedal at 2700 or 3000rpms it spits and spudders and it happens if i decelerate it from 4000rpms but if i push the pedal to the floor it goes away it only happens at those rpms.Has anyone had this problem or what it could be and it started surging alot more.I need to resolve the problem cause its driving me insane.Now sometimes if I hold it 3/4 throttle or full throttle the problem barely occurs.Swapped coils,swapped ecu,change throttle body cause i thought it might the tps with one I had and it still has the problem.

[jlevie]

That sounds like a bad AFM...

[alpineE30]

Sorry I did swap that too with my other car that runs good.

[moatilliatta]

ya. try to put some electronics cleaner under the plastic cover on the electronics

[alpineE30]

Which cover did you mean?

[kellie]

Sounds like a misfire! Have you checked your plugs? Wires?

[moatilliatta]

the plastic one on top of the afm.

[alpineE30]

Sounds like a misfire! Have you checked your plugs? Wires?

No not yet.Yeah it could be, but shouldn't it do it through out the rpm range for instance if I hold it pass those rpm ranges it doesn't do it.You could be right though.

[scabzzzz]

First thought was AFM, next thought was coil.
Check your spark plugs for fouling

[alpineE30]

First thought was AFM, next thought was coil.
Check your spark plugs for fouling

Yeah that's was my next guess cause it has something with it missing. I held it steady and listen to it very carefully and it sounds like it's not firing or getting fuel every stroke it could be the cps but I aint sure. Now wouldn't a fuel injector cause a similiar problem or atleast at that rpm range? I hope its not one of them even though I do have a few extra ones laying around.Now if its a cps wouldnt it effect the spark and the injectors? Surging what causes that?

[Mossman]

unplug the o2 sensor see if it happens. I had the same problem with my e, under load at around 2500-3000 rpm's it would stumble, unplugging o2 sensor makes it run mint. Also unclear whether your testing this while driving or idling, but you don't want to rev your car in neutral too much and definitely not above 3000 rpms, our auto trannies like to self destruct when you do that