The car runs perfectly when cold, but after it fully warms is loosing power and breaking up. The first thing I thought of was possible moisture in the distributor. Have a 95 E 420 with the M 119, this is a major issue with the M119. Pulled the distributor down yesterday including the insulator disc inspected and completely cleaned everything plus coated the back of the insulator and the seal with dielectric grease, but it had no effect.
Pulled OBD1 codes and the one code that keeps returning is 12 EZL Vacuum Illogical. Traced the vacuum line back to the intake port, it's intact and there is vacuum on the intake port and to the EZL. This car had a dead ECU when I got it a year ago and has been running perfectly since I replaced it. Cap, rotor button, wires, plugs, OVP and coil are all less than a year old. Also, both fuel pumps, and the fuel filter are new.
This is my first M 103 car with the CIS, so need some help running this issue down. I do have a spare EZL, but never heard of an issue with the EZL where it didn't just fail altogether, so?
Thanks, Richard

My '88 2.6 runs normally with the vacuum advance disabled. Be sure you plug the signal line so there is no vacuum leak. The only difference is no part throttle advance from the EZL. This lowers emissions.

So check that you don't have a leak in the line, including that formed rubber hose on the inlet manifold nipple. Mine split on the bottom side, which was tough to see without removing it and spreading it apart. That 3 mm nylon tubing gets brittle with age and can split. I replaced both the above parts. The short rubber hose to the EZL was okay, probably because it sees less heat.

Also try the spare EZL. If it works the installed EZL may be bad. If the same problem it's likely something other than the EZL.

Duke

Or the engine temperature sensor is faulty ...sensor sends a message to ecu telling it you car is cold but now its warm the mixture is to rich .