high CO emission at every rpm level

Hi, Jetronic community.
Two days ago, I went down to the garage to take the car to the mechanic to check the vacuum levels of the engine.
The engine started but the engine speed did not go up as it should.
I pushed the gas pedal the engine started to vibrate as If some pistons were missing.
Later the engine speed leveled at around 1200-1300 rpm and ran normally.
After about 100 m. I had to stop. at a red light. The engine started to choke. I shifted to neutral and tried to regulate the engine speed by giving more gas. The shaking started again. Finally, the engine died.
As the engine was still cold, I turned the idle screw slightly anti-clockwise in order to have a higher idle when I restart the engine. I was able to fire up the engine again but there was erratic behavior. All of a sudden, the rpm went up and ran very smoothly. I opened the hood and took the air filter away and started to play with the engine temp sensor and distributor cables as I thought it could be an electrical problem. In my first attempt doing this improved the engine speed but later I could not see the effect of playing with the cables anymore.
May I have your comments?

Kind regards,
Juan

Hi Juan,

this jumping effect sounds liike an electrical problem. It would be good if you could locate it further.

Hi again ,

I have tried to start the car again this morning.
when the engine is cold the engine speed is around 1800 rpm and gradually drops to adjusted idle speed of 900 rpm. Once the engine reaches its operating temperature (above 80 C) the idle drops and the engine dies. there is no way to run the engine when it is warm.
I tried to measure the engine temp sensor (on the manifold) around 40 C the value was 1,257 kOhm
why would the engine die when it is warm?

KR,
Juan

Hi Juan,
did you check the connection of the sensor towards the ECU?
As Volker wrote before, the ECU sees an engine temperature below zero when the connection is faulty and enriches the mixture so much that the engine dies.

Regards
Norbert

Hi Norbert,

Thank you for your support. When I bought the car the cable harness was in a very bad shape. So I had it redone by ordering parts here and there. I used it for 10 years. Last year with Jetronic support I got the drawings for cable harness and produced two more sets.
Before connecting I check the wiring. I have also had the ecu checked before installation.
As far as the engine temp sensor is concerned I check the values on the sensor itself and remotely at the end of the 25 pin connector. The values match the original chart. To be on the safe side I have ordered 0280140014. The air temp sensor was purchased new at MB 6 years ago.
There is definitely a rich mixture problem because everytime I go back home from a ride I smell the gasoline on my garments. Recently I checked the CO emissions the values were between 5,6 and 5,1 (after adjustment of the ecu-rheostat. ) no way to bring it down. I tried to check the -twice by Bosch readjusted- MAP sensor leakage at 0,5 bar the values did not change so I think it is working fine.
Last thing to be checked is vacuum leaks on other parts of the engine but I cannot mive the car more than 200 meters as the engine dies when it is warmed up.

Kind Regards
Juan

Hi Juan,

havin returned from a K-Jetronic workshop I can only repeat what makes a mixture extremely rich:

1. Engine temp sensor
2. MAP sensor
3. Injectors leaking
4. Wiring problems and interference on trigger contacts
5. ECU
6. full-load switch in throttle switch

All other parts have minor contribution.