Hi all:
What is the most common cause of a hunting idle in a 16v. It happens in my car mostly when it is cold. The idle will fluctuate from 600 to 1100 at idle. It will never stall, and after it warms up it generally levels off at about 950. I replaced the coolant temp sensor (the big green one at the front of the thermostat housing) which regulates the idle before the oxygen sensor warms up, but are there any other sensors that are suspect? Thanks in advance.

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1985 190E 2.3-16 Euro

Have you checked the throttle valve switch and throttle linkage microswitch for proper function?

Duie

The microswitch has been replaced. What is the other piece and where is it located?

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1985 190E 2.3-16 Euro

Throttle valve switich is on the end of the throttle shaft, which is under the fuel distributor. It should have a pigtail with a connnectir that is accessible that you can disconnect, then check for operation of the switch with an ohmmeter as you open and close the throttle. If it's sticking, douse it down with WD-40 and work the throttle until it functions consistently.

Duke

whats the resistance values for the switch?

You are going to check for open and close circuit, so you are looking a resistance of infinity when opened and usually less than 1.0 Ohm when closed.

Hope this help.

Alex