I have a 1990 190e 2.6 auto, with no cat and no lambda probe. It runs extremely rich although starts and runs well. Any body got any ideas to solve problem , and what controls fuel mixture to ecu. KE-Jectronic fuel injection. Thanks , Mark..

 

the ECU can't do much compared to the present model.
it enriches the fuel mixture during startup
it controls the idle speed valve
it gets signal from A/C to increase the rpm
it controls the electrohydraulic actuator

the engine can even run without it by substitute value using close loop function or limp home mode.

now, the question to your question is: does it have black smoke when you blip the throttle?

 

it's the electrohydraulic actuator valve mark.
this controls the flow of fuel injected according to pressure.the supply regulating voltage must be checked and can be adjusted. it's a bit complicated thing to check by yourself, and only the qualified technician can do.
the fuel distributor can also cause this.
the only thing that you can do is to check that fuel pressure regulator if the diapghram is broken. it will feed the fuel back to the intake side via that small vacuum hose and can cause rich mixture.

please post on that forum so we can share our ideas too.

 

Hi, you answered my posting before and i wondered if you could help
further.The motor is running rich and soots all the plugs and soots out
the exhaust.Tests for current to fuel pressure actuator read 9.8mA and
with a 15 kilo ohm resistor to simulate cold engine still showed 9.8mA.If
the engine was left running for longer the current very slowly dropped
to a final 1.70mA.Fuel pressure readings stayed the same for hot and
cold and were upper chamber 83psi and lower chamber 77psi which seem to
be correct. Rest pressure was 2.9 bar.I have also run engine with cold
start injector out and it stayed dry and no leakage with engine hot.I am
now starting to pull hair out! Have you any ideas now i have done these
tests.



the problem is still the EHA. readjust or replace it and your problem will be gone.

19.5 ohm resistance

4.5 -5.5 volts engine idling for airflow sensor potentiometer. this also affect if not well adjusted (backfire, stalling).

please post here.