rough idle

[rulz87]

hi!
i have a 1990 190E 2.0. recently i replaced all vacuum hoses + icv. the car starts on the first turn. then it revs to 1500 and then drops to 500. sometimes since the idle is too low it stalls. this happens only when the engine i cold. also the idle keeps fluctuating from 1000rmp to 500rmp. i have noticed that it happens only below 80degrees. any ideas? thanks in advance

[shingleback]

Did you also replace the hoses for the ICV? They tend to harden and crack, and can cause these kinds of idle problems.

[Paul E]

I have the same problem, only very intermittant.

I recently replaced just about everything, including the vacuum hoses.
he car (2.5-16 auto) runs absolutely great but occasionally (often when coming
downhill on bumpy road slowing to stop) the revs climb to 1200 and when
the car stops, the revs drop to 500 or less and maybe stall.

We have been tracking this for months but so far not much joy.

Leaning off the idle mixture has reduced it but not eliminated it.
Everything has been tested and/or new parts replaced so I think
it is probably electrical.
Until it happens all the time it is hard to trace.

[shingleback]

These problems may also be due to a failing OVP relay. You can either replace it or take it apart and resolder all the joints. Substituting a known working one is the best way to confirm an ovp relay problem.

[rulz87]

can it be the temperature sensors? how do check it functionality. i got an electrician to check my ovp. its perfectly fine. thanks