PeachParts Mercedes-Benz Forum - View Single Post - +/- EHA current

stevebfl · #12 03-06-2004, 05:45 PM

Either your understanding of the system or my understanding of your last statement need help.

You have a mechanical/hydraulic fuel metering system with a electronic mixture correction. The whole of the electronic system is to be placed over the top of the mechanical system with the system adjusted to roughly the mixture you are going to try and feedback home in on.

Properly set up with .5 -1.0% CO as an exhaust gas reading. The electronic lambda capabilitiy of -12ma to +12ma will not make the car run poorly except at the nds of range and probably then only on the lean end. The O2 sensor only gives accurate readings in the range of 0-1% CO. The car will run about the same from .25% to about 6% CO. Obviously the area of control only represents a small portion of all the mixtures that will perform good. The best running cars froma performance stand point are usually out of that control range.

You can read the sensor voltage with the sensor disconnected. If you disconnect the O2 sensor the wire going to the controller will have somewhere around .5v on it when not hooked to the sensor. It should also have the same voltage when hooked to a cold sensor. When hot the voltage of the sensor dominates the the high resistance output from the controller.

If left disconnected, the voltage on the lead from the sensor should vary from 0.0v to around 1.0v as one passes through the range of control mentioned above 0 -1% CO. If you are adjusting at the airflow meter you will run across this range somewhere between running rich and then running lean.