Idle Air Control Valve Not Getting Ground to Opening

Sorry, It's a 1987 300E (W124). Motor is 103.983.

The Haynes says about this system (Bosch CIS-E (KE-Jetronic)):

"A thermo-time switch controls the amount of time the cold start valve remains open. The auxiliary air device is a valve which allows air to bypass the throttle valve, hence raising the idle speed. A (sic) internal bi-metallic strip and heater coil controls both the amount of valve opening and length of time for which it remains open."

This suggests to me that this unit is independant of the ECU. It seems to be an electro-mechanical timing device that just gets on with one small task in a larger system. At least, that's how I read it, what does everyone else think? Mike

Mike,

Thanks for the reply. I think the auxiliary air valve is different than the idle air control valve. Does Haynes say what controls the idle air control valve?

Thanks,

Robert

Just Mike wrote in news: snipped-for-privacy@4ax.com:

Can't see that, but it does say this:

"Later variants are fitted with a rotary idle actuator. This componant replaces the auxillary air device and is driven electronically by the ECU. It provides engine idle speed stabilisation during all operating conditions, including fast idle during warm-up, and idle speed control under load, e.g. when the power steering, or air conditioning are actuated."

It also lists these:

Coolant Temp Sensor =================

-Type: NTC

-- Electrical Resistance

-- @ 80°C 325 ohms

-- @ 40°C 1200 ohms

-- @ 0°C 6000 ohms

Thermo-time Switch ================ Heater Coil Electrical Resistance 93 ohms Duration (length of time contacts are closed)

-- @ -20°C 12 seconds

-- @ 0°C 1.5 seconds

-- @ 3°C 0.5 seconds

Air Flow Sensor Potentiometer ======================== Supply Voltage 7.0 - 9.0 v Wiper Voltage Variation

-- Engine Off 0.25 - 0.5 v

-- Full Scale Deflection 7.0 - 9.0 v

I hope this is some use to you. Mike

Tugging back and forth on the computer has temporarily solved my problem. Therefore, I think the problem is either a break inside the computer or a loose wire in the harness. It's now working correctly so I will have to wait for it to malfunction again to fully isolate the cause. I did take the computer out of the case and it looks fine.

Double check your sensors. You said..."I checked it tonight with the motor stone cold at 30F and the resistance was 5,000 ohms."

Rating according to Mike is 6000 ohm at 0 degree C... so you are 1000 ohm off... this is huge. Like I told you in the first place.