On 22 september the 300E tested at:

1.1907 HC with a ceiling of 1.8000; 4.6981CO with ceiling of 30.000: 2.6627 NOx with a ceiling of 2.8000 and a CO2 reading of 431.2910... no ceiling for CO2.

On the BMW I think you may be right about the need for a richer mixture. I supect however that I may be able to tweek the NOx by increasing the idle speed to a setting above 900 rpm.

The car idled a little over 1,000 rpm after I changed the oxygen sensor and I then turned the idle screw so that the car idled at 900 rpm. It failed IC NOx so I lowered the idle to 700 rpm. It failed again. The manual says that the idle screw does not set the idle speed and that it should not be messed with because the computer will regulate idle speed. Therefore I suspect that the amount of air that the idle speed screw allows into the intake manifold is constant for the entire range of RPMs. The idle setting allows a controlled amount of air to bypass the air intake and then feeds that positive or negative air flow for combustion.

My next question is which way do I turn the screw and do I want more or less air to the combustion chamber.

Also, on the BMW, I can do exactly as you did on your Oxygen sensor test... ie feed thin wire probes into tne wiring connector and get a reading on the behavior of the sensor. But I only have a volt/amp meter and not a scope. My neighbor has a tester that is a bit more sophisticated but not as good as an ocilascope. I forget exactly how his tester works.

Here is a complete history of the failed tests:
Limit: HC 1.800 CO 30.000 NOx 2.8000 CO2 N/A
2 August- HC .7510, CO 12.1352, NOx 3.7898, CO2 349.9235

I then changed oxygen sensor and set idle to 900 using adjustment screw that should not be used to set idle speed. Retested vehicle:

20 August- HC 0.7891, CO 9.7136, Nox 2.9853, CO2 351.7512

Car failed so I lowered idle speed to 700 using the adjustment screw that you are not supposed to use. Results:

26 May- HC 1.094, CO 10.6681, NOx 3.2379, CO2 360.0925

Hope you can see something in these results.

Many thanks.

__________________
Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra