Relationship between high idle and vacuum leak?
 

Dear all:

Is there a relationship between a high idle in park or nuetral, @2000 RPMS, with a vacuum leak? For example, a few weeks ago I noticed a hissing noise from the trunk of the vehicle after I turned it off. I assume that it is a vacuum leak in the central lock system. (have not had the time to investiage) But, lately the car in park or drive, when warm/hot, idles at 2000 RPMs. It never did this before.

Can someone direct me where to start my investigation?

Vehicle:
W201
1988
190E
2.3L


Thanks,

Iggy

Vacuum leaks and high idle
 

Any vacuum leak related to the engine will often cause a high idle condition. I had one on my 450SEL and sealed it at the vac hose juncture with Red gasket sealer; the idle dropped to normal immediately. The vac door lock system would not normally create high idle -- since it is activated by a separate vac storage system that should have a check valve in it, but if the lock vac leak does have a DIRECT connection somehow to the engine vacuum systems, it could cause idle problems. Check all the vacs and seal them or replace the hoses...... BC

Engine speed is absolutely determined by the amount of air taken in. Fuel only makes it work. A vacuum leak will increase the speed unless it ruins the mixture so much that the engine runs poor.

Always remember that the speed is determined by airflow and fuel in the right quantity allows it to happen. More fuel it runs slower less fuel it runs slower.