My 1987 190E 2.3 will only idle if I disconnect the power to the idle control valve (otherwise I have to keep the accelerator pressed or the engine will stall).

With the idle valve disconnected the engine idles at 900 RPM when cold but gets upto around 1400 rpm when warm (Limp home mode I assume ?).

I have monitored the current to the valve and have found the following ;

- 570ma when the engine is running at above 1,000 rpm.
- if I take my foot off the accelerator , the current then increases rapidly to around 900ma as the rpm's drop until the engine stalls.

It appears as if this current increase is not enough to keep the engine running as it always stalls when I take my foot off the accelerator.

The idle control valve appears to be operating corectly as when I connected it up to a 1 amp power source the valve opened almost fully.


The likely culprit of the OVP checks out o.k.

Do you think the idle control valve is faulty or could it be the sensors that feed into the KE-Jetronic computer that are playing up ?


thanks
Doug McCutchan

There are four sensors that are involved so that the engine will have a correct idle. These sensors are throttle switch(on butterfly), decel switch (on linkage), throttle position sensor (on air flow housing), & speed sensor on speedo. ALL must function correctly so that the engine will idle correctly!!

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thanks, I'll check them all out.