The car is a 1993 190e 2.6L engine
I rebuilt the head with new guides and seals. The car started fine and idled great like before I did the head job. after about 150 miles it started to idle high after start up. To be more specific, I start the car and idle goes to about 900. Let it idle for 5 minutes and it doesn't drop. If I push the gas slightly to about 1200 rpm, it goes to it and stays there. A little more gas to 1500 rpm and goes there and stay at 1500. I noticed that when I unplug the idle valve, the idle goes back normal and stays there when I reconnect the connector to the valve. If I turn the car off and restart it, it goes high as mentioned and drops when I put the valve connector. With the valve connector off and car idling good, turning the A/C on drops the idle to about 400 and car idles failrly Ok. Turning the A/C off brings the idle to about 700 rpm (normal). My OVP is 3 months old. There are no vacuum leaks. I checked the on/off ratio at pin 3 and it fluctuate around 50 so I assumed the oxygen sensor is ok. I haven't checke the EHA current and will do that in the next 2 days. I checked the switch by the throttle linkage and it read 0 ohms at rest position (car not running) and infinety at WOT and even when I move it slightly so I assmed it is ok too. I will clean the valve tomorow with electrical part cleaner and see what happens. Any other things to look at?

PS. The issue happened after I degreesed and washed the engine if that may trigger ideas
Meza

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Meza
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer

Same thing with mine, or similar.
could be the idle compensator (air slide) or the ecu sending a dodgy signal to the idle compensator.

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Andrew
300e 294,000mi
380sel 185,998mi
380se 309,980mi

Meza


Did you ever fix the problem you had?. I just rebuilt my cylinder head and have the same problem. I also washed and cleaned my intake with engine degreaser. Could water enter the throttle position sensor and damage it?

TIA,

Paul

Have you checked your temp sensors and associated wiring?

Good luck,

Check all the KE electrical connectors for corrosion. Give them a good visual inspection, clean off any observed corrosion, then clean them with contact cleaner. Some water probably got into a connector from the engine cleaning and is causing high resistance.

Duke