Runs on 3 cylinders(w124).

[G.e.o.r.g.e]

It's about a w124 sedan,1990,M102.963,WDB1240211B384210

The car starts very hard.
Once warmed up a bit 40'ish celsius it runs great.
I noticed a red/green wire(with the connector cut off) rigged to a brown wire that belongs to a 2 pin connector,that belongs to a 3 pin sensor on the head.
If i remove the red/green wire the car starts great but it seems to run very bad ,like it runs on 3 cylinders and white smoke comes out the exhaust.

This is the red/green wire i'm talking about.





And the sensor wire that the red/green one is rigged to.



The internet knows nothing about this wire,where it comes from,where it should be and so on

[optimusprime]

Looks like viscose fan temperature guage. Can you go to Google search page, on there look to the top you will see immages click on it ,then in the box put Mercedes M102 engine temerature sensors. Click on the item view page . It will take some time but you will find it in there.

[G.e.o.r.g.e]

@ optimusprime

Thanks for your relpy but...when i said i can't find anything on the internet about that wire...i meant it.

And as for the image web search,believe me i tried every single rotation of words for my problem.

Have a nice day !

[optimusprime]

That looks like heavy guage wire ..Can it be an item thats been removed .i have a m103 if it was like yours i could check it out for you . You need some one that is willing to help you who owns this type of engine. Do you have a wiring diagram? Would you find it if you had

[G.e.o.r.g.e]

Hi optimusprime !

I just got home from the car.
I checked the jetronic wiring harness,and that green/red wire comes from the KE-Jetronic ECU behind the battery.
Now i just have to find out where the hell it has to go.

I can't say i could find the wire on a diagram.

[Rick76]

A green/red normally goes to the coolant temperature sensor.
I'm not sure if I have a wiring diagram and sensor location for that car but I'll take a look.
What colour wire goes to the third terminal of that 3 pin (2 connector) sensor? I can see green but not the stripe if there is one.

[Rick76]

Can't find anything describing which sensors are which but the green/red wire should go to a NTC temperature sensor in the coolant flow. Because it is a negative temperature coefficient thermistor, by not connecting it the computer thinks that it is very cold and will give a very rich mixture. By connecting it to that brown wire which is probably a ground, the computer thinks the engine is very hot thus your poor starts

[G.e.o.r.g.e]

Originally Posted by Rick76

A green/red normally goes to the coolant temperature sensor.
I'm not sure if I have a wiring diagram and sensor location for that car but I'll take a look.
What colour wire goes to the third terminal of that 3 pin (2 connector) sensor? I can see green but not the stripe if there is one.

Hi Rick76 !

The single pin connector has a (just)green wire.
As for the 2 pin one from the 3 pin sensor,i have to go to the car and take some pictures.

Originally Posted by Rick76

Can't find anything describing which sensors are which but the green/red wire should go to a NTC temperature sensor in the coolant flow. Because it is a negative temperature coefficient thermistor, by not connecting it the computer thinks that it is very cold and will give a very rich mixture. By connecting it to that brown wire which is probably a ground, the computer thinks the engine is very hot thus your poor starts

That's true,the car starts very hard when the green/red wire is connected on the brown one.
When i disconect it from that wire,the car starts right away but runs like hell,white smoke and the engine seems to run on 3 cylinders.

Thanks !

[Rick76]

Somewhere in the head or a coolant passage near the head, there must be a coolant temperature sensor.
The North American versions around that year had either a 2 pin or 4 pin sensor. The 2 pin had 2 separate thermistors going to ground though the sensor housing. The 4 pin had the 2 thermistors going to diagonal pins with separate ground wires. One thermistor is used for the ignition module and the other (green/red wire) goes to the injection control computer.
Thermistor resistance at 20 degrees C is about 2.5K ohm.

[G.e.o.r.g.e]

Come on...there has to be someone with the same engine type who can help me out with some pictures on that wire or some info.

[optimusprime]

bye.

[Stretch]

George,

You can't always rely on the colour codes of wires. BUT If you had a vehicle that was supplied to the US of A then you'd have a fighting chance of finding the wiring diagram on www.startekinfo.com

As it is you have an engine that is similar to those used in a W201 so perhaps those wiring diagrams will help.

Have a look if you want to...

...I reckon, however, (as said before) the fastest way of working out what the wire does and what it is for is to trace it back to the ECU plug. Just do a simple continuity test and tell us which pin number it is. From the information in the W201 FSM there are (perhaps) three different ECU plug types so we can narrow it down to a few possible components.