190e running rich with eha on/off.Bad mpg.Help! - PeachParts Mercedes-Benz Forum

#11 09-01-2003, 12:08 PM

Steve

Believe me, I have read other posts with regards to EHA current and I cannot understand the readings I am getting.

As far as the decimal point is concerned, I'm pretty sure it's in the right range coz I'm using an analog ammeter with the dial-type setting.

Set at 250mA and 25mA produced very slight (almost zero) readings.Only when I set it at 2.5mA full scale deflection, then I could see the reading at idle/acceleration.

At accelleration, the needle swung negative so I switched the terminals to see the reading and I got 0.25mA - at both constant rpms.

I may have screwed myself on the scales so I'll scrutinise it once more.

But if the readings are correct, it would mean that the readings are actually zero all the way!

So far I have run the car with the EHA on and off - but the O2 sensor still connected.The only reason I have not done the O2 test is that I have frustrated myself looking for the connector.It doesn't seem to be anywhere under the passenger side or the driver side carpet.If someone has a photo showing where it's at on their 190e, it would be very helpful.

It doesn't help that mine is a 1991 190e 1.8 Euro RHD so some of the stuff in my car may be different from the US cars.

Steve, by disconnecting the EHA, the O2 sensor is also out of the equation isn't it?So if it's faulty, with the EHA off, I should still be able to adjust mixture to run mechanically well - but I can't.

Not being able to find my O2 sensor connector is really a bugger coz I am unable to check if it's working - if i could verify it's OK, I could try to get the car in closed loop.

Quote:

If you are off one decimal point you are twice the values I give for max readings in either direction. A very likely senario could have 12ma at idle and -12ma at both other rpm ranges. Such a group of readings would be characteristic of a vacuum leak. It would take full mixture correction at idle but that correction would leave it too rich at the higher rpm where the leak is small in proportion, thus the minus readings off idle.

I found this information really interesting.It also makes perfect sense.But would a vac leak screw my mixture adjustment efforts with the EHA off?It would seem to me that the engine is getting some kind of "false air" so it is dumping fuel to compensate.

Although frustrating at times, this has been a sensational learning experience for me coz along the way, I have learned to test/check various sensors/switches/etc of the KE-Jetronic system.Cool!

Steve, sorry for the long post and the seemingly vague questions tossed in every paragraph or so.

I thank you for your patience.

Cheers.