Help please for 535i 1989 Automatic

[thejet63]

Hello folks,happy new year and heres hoping someone out there can help me.

My 535i is playing up,it started about a month ago and has got seriously terminal now.
The car starts ok (runs a bit rough though) and in park or neutral seems ok
but when you start to drive between 1500 and 2000 rpm will not pull at all and then the revs drop the car gives no reaction to the gas pedal and then cuts out (not that great on an automatic no brakes , power steering etc etc).
Have done the usual filters (gas and air ) plugs ok but changed them anyway
and set them at 0.86.
Have been told that it is probably a fault with the air intake valve?

Can anyone help out there please as i want to keep the beast on the road because having a British licence plate in Italy saves me money on all aspects of motoring plus the car even though its 17 nearly 18 years old for me still has a great deal of life in it .

[bill g]

By air intake valve they probably mean the airflow meter (AFM) - that is the large component on top of the engine with black plastic cover (above valve cover).
It could be the problem, especially if it has large mileage (it has moving parts that wear). Have you tried revving the engine from idle gradually up to say 4000 rpm - if you get faltering or stumble or engine cuts out then the AFM becomes a more likely suspect.
You can test the AFM with the engine stationary. Remove air cleaner and inlet duct from the meter so you can reach in and move the moving door or flap by hand. Hook up a high impedance digital voltmeter to the AFM output signal (terminal 2) and earth (terminal 4) at the airflow meter. In this context the terminals are numbered in order with terminal 1 at opposite end to the blank pin. The wiring plug will need to remain connected to the meter to do this test so you need to tap into the wires somehow.
With ignition on, move the flap slowly through its full travel - you should get something like 0.25 volts closed, gradually rising to about 4.6 volts with flap full open. Importantly there should be no dropouts or interruptions as the voltage changes - the voltage should increase smoothly.
The parts that wear are under the smaller black plastic cover on bottom of meter - it is glued on but can be removed using a knife with care. There is an arm with a contact that slides over a track which can wear badly - this tends to happen at the lower rpm area where the thing spends most of its time. There is a fix for this - do a search. Alternatively replace the airflow meter.

Bill G

[bigtisas]

I'll check for vaccum leak(s) and clean the Mass airflow sensor with some cab cleaner. Search the net for "clean MAF".

[thejet63]

I'll check for vaccum leak(s) and clean the Mass airflow sensor with some cab cleaner. Search the net for "clean MAF".

Thanks for the replies folks,well just got the car on the road today and the problems was,the fuel pump.
It had snapped,yes the metal housing was broken.
Its the first time a BMW mechanic had seen this happen (and he's got over 30 years experience on Dubbs).
Anyway also changed the water pump as this was going,fuel filter,fan and managed to get a second hand fuel pump for 150 euros (new BMW wanted 350 euros).
The beast is alive and kicking again and the smile is back on my face (well apart from my next job which is the radiator still trying to fing a good second hand one)
It's like being a kid again with this car,it may have 18 years but it will still pull 140 mph,from 0-60 its like the proverbial of a shovel and it still looks good,though the fuel bills are high and all goverments are trying to make us get rid of them in Europe (more so in Italy) long live the 535i.