Desprate need for help! Jerking 316i

[cerbera84]

Hi

My 91 316i has started jerking once it gets above 2000rpm and under acceleration. Its been doing it for about a month but recently it died down, but i filled it brim full of petrol and its started again worse then before. I've taken it to a garage and they replaced the spark plugs, leads and cab arm, which hasn't helped. Could the problem be caused by a blocked fuel filter or something?

Thanks for looking

[Dr Firefly]

If you hold the revs over 2000rpm without any load on it - ie in neutral, do the revs pulse up and down? Or does it feel like it could be something mechanical in the drivetrain?

Perhaps the air flow meter? Mine did something similar at higher revs when holding at a constant speed but was fine when I changed the AFM. What do people think? Or could it be the fuel pump dying?

[cerbera84]

its seems fine in netural just under acceleration or cruising above 2000rpm. But now that you mention it ever since I got it in march when you first start it it revs ups and down for a few moments before it stablizers. What is the AFM, is there an easy way to test the fuel pump?

[maxfield]

What about dizzy cap?
The AFM is airflow meter which is a small box sort of thing and is on the inlet side of the engine.

[cerbera84]

the arm in the cap was replaced by the garage, but it hasn't helped, I think it might be more fuel related as its got worse since i filled it with petrol.

[316eyes]

If the problem is like a misfire, I had a similar thing with mine. Ran perfectly normal around town but under load on a dual carraigeway or on the motorway was when the problem occurred.
Changed the fuel pump and it was sound after that.

[jog5000]

I had the same problems, checked the dizzy cap, turned out there was some muck on the connectors that the leads clip onto.
I discovered this after a motor change, fuel pump change, lead change, sparks change....... and now it runs fine after I took a small screwdriver to the dizzy and scraped out the crud.

[FBF]

if it was me id go to a local meet and swap my maf (air flow meter) with someone elses. only take a few mins. i bet that solves the problem. sounds exactly like it. then get one on ebay or from one of the biatches that kill these wonderful cars for parts..