idle problem

[pecandarosa4214]

My 1992 525I has a minor idle problem that I cant figure out. When starting up or sitting in park the car idles beautifully, but if your driving and you start to stop the car idles up for a second then idles down and the rpm drops suddenly below 500 and the car stalls. I did find out when you are stopping, if you keep the rpms above 500, when the car comes to a complete stop it will idle ok after a second. Does anybody have any idle what it could be?

[ruf-porsche]

Vacuum Leak

[ThoreauHD]

Ditto. Vacuum leak.

[sstuner]

good call guys,

def a vacum leak.

but from where.

the brake booster uses engine vacum to boost the brake pressure so when you push on the brake pedal it opens a little valve in the booster allowing the engine vacum to suck on the diaphragm in the booster moving the piston in the master cylinder which applies your brakes with more force than you can manage on your own.


so idles fine. runs fine but stalls at the lights....

does it only do this when the engine is warm??



check the line that goes from the engine to the booster. check the rubber grommet on the booster,

are you losing brake fluid and there is no sign of a leak? and i dont mean the normal amount that "dissapears" over time. that is normal.

let me check something and iwill get back to you