the TX test calls itself ASM version 0305.
Dilution is given in % at the bottom of the page and I do not know more except the test wants it to be >6%.
My cat has 320K miles on it. I checked O2 sensor has 320K miles also.

thus my O2 sensor must be ok if the CO is low-true? If so I will not change it at the next tech session.
Thanks.

Wow! 320K miles on both the catalysts and O2 sensor. Yes, from the CO reading the O2 sensor appears to be okay. Just make sure everything is hot as possible for your next test.

Duke

I just barely passed the smog test. I'd appreciate commentary on the following numbers, as I'd like to make sure that I implement all of the necessary adjustments so next time it is not so close.

15 MPH

measured (max)

RPM 1525
%CO2 15.5
%02 0.9
HC(PPM) 110 (110)
%CO 0.28 (.71)
NO (PPM) 676 (850)


25 MPH

measured (max)

RPM 1479
%CO2 15.0
%02 0.8
HC(PPM) 53 (85)
%CO 0.13 (.59)
NO (PPM) 271 (783)


Thanks in advance.

Steven

__________________
Steven
1989 260E (276K miles)
1995 E320 (50K miles)

As is typical for 103 engines you are on the ragged edge of HC at 15 MPH. The 25 MPH numbers are always better because the converter heats up during the 15 MPH test. Given the relatively high level of oxygen there is definitely room for improvement to reduce both HC and CO, and the hotter the converter the better it will oxidize HC and CO.

Frankly, with the level of O2 you have I'm surprised it passed. It's common to be at or near the HC limit with a tenth or two percent of O2. The fact that you have relatively high O2 and reasonably low CO indicates a good mixture, and no adjustments are necessary. For your next test make sure the converter is as hot as possible.

Always drive the car for at least 15-20 minutes before the test, preferably with a freeway run. Go to a "drive through" test establishment at a time when there is no line so you can get right in. Prior to turning the car over to the tech, keep the engine running at 2000 revs in neutral with the defroster on so the A/C compressor puts some load on the engine.

If possible, go on a rainy day and ask them to run the "tire dry procedure". They will run the car on the rollers with no load at 2000 RPM for about a minute, and this will heat up the converters.

The 103 engines are typically near the limit, especially at 15 MPH, even in perfect adjustment and operating order, so you have to "manage" the test procedure to ensure that the converter is as hot as possible when the test begins.

Duke

Thanks very much Duke. I'm happy to hear my mixture does not need further adjustment, as I just finished modifying my lambda settings a week before the test, and I wasn't completely sure how well my mixture adjustment would work out.

__________________
Steven
1989 260E (276K miles)
1995 E320 (50K miles)

Duke,
I passed NY inspection with the following:

1988 300ce - 85,000 miles
limits / results
HC- .80 / .44
CO- 15.00 / 2.20
NOx- 2.00 / 0.45


1998 ml 320 - 87,000 miles
HC- 220 / 164
CO- 1.2 / .59
NOx-N/A

The 300ce I adjusted myself after purchasing from PO. The ml is still at factory settings from when I purchased it new. NY has only onle test, I don't know at what mph they run the dynometer. I wasn't there when the tests were done but since I left the cars I suspect the cars were cold when the results were taken.
Thanks so much for your comments.
Richard

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)

I'm once again struggling throught CA emissions tests and would like to share my test results with participants in this thread:

First Emissions Test since passing in 2007

MPH=15 RPM=1507 %CO2=14.9 %O2=0.2 HC(PPM)=84 CO(%)=.30 NOx(PPM) =1032 FAIL
MPH=25 RPM=1530 %CO2=14.9 %O2=0.1 HC(PPM)=43 CO(%)=.24 NOx(PPM)=525 Pass

Replaced CAT with an aftermarket model (Magnaflow).

MPH=15 RPM=1498 %CO2=11.6 %O2=4.6 HC(PPM)=28 CO(%)=.09 NOx(PPM) =944 FAIL
MPH=25 RPM=1488 %CO2=11.5 %O2=4.6 HC(PPM)=21 CO(%)=.08 NOx(PPM)=899 FAIL

Reset duty cycle (enriched mixture)

MPH=15 RPM=1520 %CO2=15.0 %O2=0.1 HC(PPM)=53 CO(%)=.03 NOx(PPM) =1508 FAIL
MPH=25 RPM=1793 %CO2=15.1 %O2=0.0 HC(PPM)=44 CO(%)=.06 NOx(PPM)=1156 FAIL

Why did CO drop so low after replacing CAT, and stay low after enriching the mixture? I would also have thought that NOx would have decreased after eliminating O2.

__________________
Steven
1989 260E (276K miles)
1995 E320 (50K miles)

How old is your oxygen sensor?

Sixto
87 300D

Sorry, wrong direction. High NOx indicates faulty EGR.

[edit] Actually it indicates high combustion temperatures. EGR keeps combustion temperatures in check but the engine might be running too lean for other reasons which I think is what you tried to resolve by enriching the mixture. Do the tests end with the car at speed or does the cycle include coastdown?

Sixto
87 300D

O2 Sensor was replaced prior to test in 2005, so 4 years old. Seems to be sending feedback to Jetronic okay, but plan to check O2 Sensor electrical connection point later today.

No EGR on this model.

California emissions test, I think they collect all measurements at specified velocity (15mph & 25mph).

Yea, I've read ALL the material from the experts here on NOx formation at 4000F - peak combustion temperature. If I am unable to get NOx undercontrol via the related Jetronic adjustments, I'm afraid I'm going to have to retard timing through the changing of that little resister (I'd appreciate it if someone can direct me to instructions on that).

What I still don't get is the significant reduction of CO, and whether that has a positive or a negative impact on NOx formation.

__________________
Steven
1989 260E (276K miles)
1995 E320 (50K miles)