Data reported: 02,%; HC, ppm; CO,%; NOx, ppm. The three numbers are Max Allowable/Average (for the 1988-1993 year group)/Measured . There is no limit or average for O2. It's a diagnositic tool. (BTW, one ppm equals .0001 percent. The report reads out constituent gases in the units reported to keep from having too many zeros before of after the signficant digits.)

15 MPH (1626 RPM - 2nd gear) 0.0 ; 116/31/73 ; 0.74/0.10/0.12 ; 791/237/21

25 MPH (1657 RPM - 3rd gear) 0.0 ; 091/20/47 ; 0.62/0.09/0.13 ; 730/199/20

Previous test (2003)

15 MPH (1657 RPM - 2nd gear) 0.1 ;116/31/113 ; 0.74/0.10/0.36 ; 791/237/261

25 MPH (2665 - 2nd gear) 0.0 ; 91/20/58 ; 0.62/0.09/0.18 ; 730/199/188

I was first in line behind a car in bay one (of three) at Auto Check Inc #7 - a drive through "test only" inspection station in Manhattan Beach and waited about 5-10 minutes keeping the engine at 1500-2000, and the engine was thoroughly warmed up when I arrived (idle oil pressure 1.5 bar). The temp gage climbed to 100, which tightened up the fan clutch, and by the time it got into the bay, the electrics were cycling. The outside temp was mid sixties with partly cloudy skies.

A couple of days ago I ran complete diagnostics on the lamda system (which includes the O2 sensor, which is original) and everything was nominal. I installed a new set of Bosch H9DC plugs. The old plugs only have 15K miles, but a fair amount of deposit buildup. Unfortunately, much of my driving is around town - fairly short trips - but I try to give her an "Italian tuneup" whenever opportunties arise!

HC is still high, and I attribute it to quench area or uneven fuel distribution of the KE injection system - or maybe a combination of both - both of which are design issues and cannot be "fixed".

Note that the zero percent 02 on both tests indicates that the converter was operating at maximum oxidation efficiency, so there is really no way to significantly lower HC or CO any farther. The fact that essentially all the oxygen was used in the 15 MPH test indicates that the converter was hot enough at the start of the test. Often, a high HC count at 15 MPH is accompanied by a tenth or two percent O2 and this means the converter is not hot enough to achieve maximum oxidation efficiency, which can cause a test failure by exceeding the HC limit The converter will cool down with too much idling or (heaven forbid) shutting down the engine prior to the test. Proper "conditioning" as stated above should help you avoid this pitfall.

The test tech was a good guy who was blown away by the condition of my car, and he treated it with great respect. I hope he's still there in two years!

Some additional insight on how to get your KE-equipped Merc through emission tests is at:

M103 Emission Test Insight

Also see 87 300E Fails Ca Smog for a discussion on ignition system issues/problems that can cause misfires, whilch can result in high HC readings, especially if part of your emission test protocol includes an idle speed test. [added 7/28/05]

The following site explains how to check the lambda system duty cycle"

http://landiss.com/mixture.htm

The following two sites have Mercedes Benz service procedures

http://mb.braingears.com/
http://skinnerbox.steaky.org/

One other note. The "reason for test" is stated as "1.9Random Sample" This is a new one to me, and I did not get what I consider to be a satisfactory explanation from the test station people. This was the normal bienniel test, and the reason is usually "high emitter profile", and I am directed to a test only station. If anyone knows what this "reason for test" means, let us know. I may have to query the BAR for an explanation. If past experience is any guide I will probably have to contact my state senator's office for help in order to get a lucid response from the BAR.

Duke