e39 540 auto - funny tickover/surging problem - any ideas?

[papercup]

Hello

when driving the above i notice the tickover seems low; around 500rpm

when you start it and leave it ticking over the revs surge every now and then; up to maybe 1500, then straight back down

this has now started happening when you slow down; as the revs drop to tickover, or just after they have, the revs surge and being an auto, the car surges forward. But i am on the brakes so it surges against them and the car bucks.

for the first time this morning the car simply stopped; the tickover dropped too low perhaps? It was just after i'd pulled away, then slowed for a junction. The starter wouldn't engage at all; i had to take the key out and put it back in to start it

seems like something that is getting worse...

any ideas? My mate, fount of all knowledge, says its the air-flow sensor (is that the same as a MAF sensor?) and that they get gummed up and dirty and it wants a good clean

all advice welcome

cheers

Andy

[eliot]

papercup said:

Hello
any ideas? My mate, fount of all knowledge, says its the air-flow sensor (is that the same as a MAF sensor?) and that they get gummed up and dirty and it wants a good clean
Andy

More like the idle valve assembly.

[colinrob]

Had problems with mine not surging but stalling it was the cam sensor try to get it pluged in to a diagnostics set it will work out cheaper in the long run rather than chasing/changing all the wrong sensors