Coolant temp sensor (CIS/EZL)
 

I think I may have finally figured out what is plaguing my car.

I was working on the 16-vlv last night down @ RC Imports & was trying to troubleshoot where my power loss & sporadic start problem are coming from.

Here's my question. On the coolant temp sensor for the 16-vlv has two leads. When the leads are pulled during idle the car should stumble & the idle should act weird.

When I pull mine the idle stays constant. I looked at the schematics for these leads. Both green wires, one w/ a red trace & the other black. Apparently there are four (X48) diodes soldered in somewhere on these wires. I am assuning that one is the R/16 and the other three I am unsure of...

With a failed diode in line would it be possible to be getting feedback through the diode which in turn would cause incorrect signals to each unit?

coolant temp sensor
 

Hello Potomac Pat,

I am glad there is someone in the world who also thinks that a bad temp sensor input is causing problems to the car.
My car 1989 230E has 2.3 liter 8v engine. It idles at 800 rpm when the ingine is hot or cold. I think that the car should idle at higher speeds when cold. Disconnecting the temp sensor should change the engine's speed. My car does nothing when I disconnect the 4 pin temp sensor. I have posted it's picture. The temp sensor is part #1 in the following link.
http://www.peachparts.com/shopforum/tech-help/54547-1-engine-3-temp-sensors.html
If you can read the schematic you can look at the KE Jetronic system's detailed schematic below. It will take you 20 seconds to download this with a modem. Don't ask me if I can read the schematic for you because I don't understand !@#$ in this.

http://www.autolib.diakom.ru:8001/CARS2/main/Mercedes-Benz/shematic/controller/KE-Jetronic/mke.pdf

Hurshi

I don't know which 4-pin connector you are talking about?

The coolant temp sensor on the 16-vlv is a two pin connnector. I changed all of the sensors on my head two weeks ago w/ new parts.
I can read the schematics, but I am wondering if the feedback through a failed diode would screw w/ the CIS/EZL signals during normal operation !!!

Pat, why do you say the engine should stumble and so forth when the temp sensor is dis-connected? True, the fuel mixture depends on coolant temp as well as several other inputs, but when you dis-connect it, the CIS-E control module enters a fixed mode to maintain driveability. I'm not sure about the diodes you mentioned either. If I have time I'll look at the wiring diagram at work tomorrow.

I agree this is probably normal. Pulling the lead does nothing. Nothing happens on my 2.3 either. The EHA on the other hand, mess with that and and the idle goes to hell.