Car in question is a 1992 300E with 129K.

Car will idle at 2000- 2500 RPM once above 80 degrees.

If I unplug the idle control valve idle drops to about 1100 in park and 750 in drive, starts and runs fine.

Problem started after replacing air flow meter boot, idle control valve hoses
which were cracked. Also replaced breather hoses, valve cover gasket, O2 sensor, and all accessible vacuum connectors.

Fuel injectors and seals have also been replaced. Temperature sensors are new. Cap rotor plugs and wires are also new.

Car runs good with new idle control valve unplugged. Plug it back in high returns.
Duty cycle and potentiometer are in spec

Please help I am baffled.

Thanks in advance
Paul

Is the connector keyed to hook up a certain way on the ICV?

When I purchased my SDL it would idle around 500RPM, not correct due to the ELR system to control idle. The plug for that on the back of the IP was reversed... I flipped it around and it went right back to spec, which is around 680RPM as I recall.

How about the throttle switch on the side of the throttle body?

Did a PO fart with the linkage to control the idle speed due to the vacuum leaks?

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

The ICV connector is keyed.
I did remove the throttle switch when I cleaned
the throttle body and intake.
I am going to check if the throttle switch is installed incorrectly,
as in off by 90 degrees.
I think the potentiometer was adjusted to compensate for the
multiple vacuum leaks.
The car had a leaking EHA valve and was adjusted rich.
EHA was replaced and mixture adjusted, several years ago.
The high idle is present with the linkage disconnected at the
throttle body.
I will check throttle switch orientation.

Problem solved
Throttle switch was installed incorrectly. There is a rotational range of several degrees provided by the
mounting screws being smaller than the holes in the tabs of TPS. Centered on screws all is good.