lurching 91/525i

[Bmwbill41]

I need help...my 91/525i stick with 215k miles tends to randomly stop and quickly restart in a fraction of a second in low rpms??? I call it lurching,,the back wheels will spin as it reingadges......I've changed plugs , fuel filter, air filter(k&n) plug boots.....Took it to BMW there where no codes in diagnostic.......I'm ready to drive it off a cliff!!!!
Please some one help... Thanks....

[Kalevera]

Search fusible link.

Especially if you've got the battery under the hood; the fusible link that lives on the front PS strut tower is known to finely crack and cause all sorts of stupid problems.

And drive it to my house before you drive it off a cliff, I'll take it.

Seriously.



:D

Welcome to .info.

best, whit

[t_marat]

Maybe fuel pump not creating enough fuel pressure?

[Paul in NZ]

distributor cap/rotor,check for cracks and clean of dust/91 is m20 right?

[neil_004]

I have a 91 525i auto. My car stutters at appx 2500 rpm under heavy load and will sometimes hesitate, complete loss of power, for a split second usually off the line. I dont get any diagnostic codes but when it happens the check engine light flashes briefly. I am not sure if this is the same problem that you are having. My fusible link became intermitant a while ago and I replaced it, hesitation was present before and after the link. I have the M50.

[SRR2]

If you rule out the other obvious causes, I vote for the AFM. It will do exactly what you describe -- erratic low speed operation, inability to idle, wrong idle speed, no low speed torque. Just went through this exact thing on the 325iX. It was undriveable the way it was. Ruled out the usual suspects and was left with AFM. Turned out that the pot element was contaminated and worn such that it produced resistances that were way too high at idle -- sometimes. You can 'repair' the AFM, sort of. I'd consider any repair temporary at best. Eventually you'll have to replace it.

Search for my other posts on the subject.

[Kalevera]

Steve, the M50 uses a hot wire MAF. Could still be the culprit, and if a replacement is sought out, note that the M50TU ('93 and on) mafs aren't interchangeable with the M50 units.

best, whit

[SRR2]

Ok. I thought the M20 was used in the 5 series until 91 or so. Therefore, cancel everything I said. I suppose it could still be a MAF problem, but much less likely so with a 'solid state' type.

Thanks for straightening this out so the OP doesn't go crazy looking for something that's not there.