190e 4 cyl running rich
 

hi all new to the forum, just wanted some imput. I have a 1984 190e 4 cyl., a little history, car came from an action, had bad head gasket. replaced head gasket, intake and exhaust gaskets. starts hard, runs good until out of warm up mode, idle is not to rich but when accelerated above 2000 rpm it goes full rich. I have checked the fuse on the load reduction relay and its good, checked all the other fuses. looks like someone has been into the fuel distributor. upon removal the lock tab washer on the bottom side has been altered and the nut has plier marks on it. so my question, does anyone have the spec on the fuel dist. plunger height? secondly, I have voltage at the eha valve on the fuel dist. but the voltage variation is very slight, so is the o2 sensor gunny sack also, if so unplugging it should stop the full rich running correct?, but it does not change anything. so is the fuel dist bad? where should i go from here. :confused:

If you had a bad head gasket, you will need to replace the O2 sensor. I don't think they like glycol and I know then don't like burning oil.....

Next, you need to measure the duty cycle at the diagnostic connector (I think it's the round one with a screw cover on the fender like the one on the W124, but someone will correct me if I'm wrong). I think duty cycle should be 50% at idle, engine warm, but flucuating. If it's steady, you have a problem.

You have to measure CURRENT at the EHA, not voltage. Should be 8 mA in normal operation, drop to 0 for full lean (fuel shutoff on coast) and go to 16mA full rich.

If it runs fine until its warm, chances are the fuel distributor is fine, although it's possible it's been monkied with (I hate hammer mechanics!). Replace the oxygen sensor and re-set the fuel mixture properly before getting too excited -- it's entirely possible someone messed around with the mixture to cure the "rough idle" from the bad head gasket!

Peter

thanks for the reply, so if I unplug the O2 senson should'nt it put the eha valve at 8ma to run at middle fuel mixture, not full rich? When I did this I got no change in running condition, still fullrich. So my thinking is the O2 senson is ok but still have fuel dist. or high fuel pressure problem. Thoughts.