a few things
 

1. I'm using H9DCO plugs
2. I've cleaned the ICV and replaced, but upon initial visual inspection it appeared clean.
3. ICV exit hose is cracked where it connects to ICV. I've reassembled and placed a clamp around the hose until I can purchase a replacement. Idle is slightly rough.
4. I was unable to locate EGR system. I need to do more research, but can anyone confirm if the '89 260e has an EGR valve.
5. I was unable to check lambda - need to pull my voltmeter out of storage.
6. Last, I have never reset the timing in my vehicle. Can someone please walk me through the steps. I did a search on these boards but was unable to located instructions.

Thank you.

Steven

Four years later and here I am again trying to squeak past the CA emissions test. Here are my results:

BEFORE replacing CAT:

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


AFTER replacing 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

Please note that on the 2nd test the guys let the engine get very hot. When they gave me the car the temp gauge registered 120C and the electric fan was going. So, I'm more than a little disappointed as it appears they didn't put a fan on the engine during the test, even though it was a very hot day and there was a line, and so I'm not sure how reliable the second test was.

I've reread some of the previous posts in this thread and have made sure the Lambda setting are within spec, that all vacuum leaks were repaired, the 02 sensor is approx 4 years old, the car normally runs at about T=90C with a new thermostat, Oil has been recently changed, new H9DCO plugs installed last month. And last time I checked, I got the following readings: Fuel pressure @4.8bar. Lamda @45%. Vacuum @18in.

What am I missing? Given the high O2 readings in the test AFTER the new CAT was installed, I'm wondering if the guys could have damaged the O2 sensor when they cutoff the old CAT?

On Edit: going back through this thread and my test/repair history I see that my CO dropped considerably after changing the CAT. Can anyone explain this... and will this also have an impact on my NOx values?

Ouch, 4 years and counting! Sorry I can't suggest a fix for the high NOx reading, but if you're still wondering about the EGR, your '89 M103 did NOT come with EGR or air pump. Those were added beginning MY '90, even in CA version cars.

Oh, sorry if I was misleading, Cal, but the car DID eventually pass emission each of those times, it's just always a struggle. It's just that my turn is up again .... and here I am going thru it just one more time. I've been through many of the suggestions here, finally replacing my CAT. The oddest thing is the high O2 readings in the post-CAT test... I just don't get that.

I love my '89 300CE coupe, but shutter from fear every two years when I have to have the thing smogged. It always passes, usually with a little coaxing from the tech, but some day...

That's one of the main reasons I recently purchased a Mercedes diesel. No smog checks! Still undecided if I want to dump the coupe or not. It sure is fun to drive, but in this economy, isn't worth much.

looking at your test results after the cat replacement it would seem that the car is running way too lean[ low co2 readings,high o2 readings,very low co readings] you may have adjusted it to compensate for a worn out cat and now that it has been replaced i suggest that you richen it up and try to get the co2 up to 14.7----14.9[this is a measure of efficiency]this should raise the hc to around 50 and the co to .2----.4.this will also bring the o2 down to between .2 and .3 now you have no oxygen left for the formation of nox and it should drop down well within limits.

Thanks so much for the informative reply.

The last time I adjusted lambda (pre-CAT) it was at 45%. Are you saying that with the new CAT that reading will have changed, and therefore lambda needs to be readjusted?

I'm just a little confused as to how I can adjust lambda to attain the CO2 level of ~14.7 without also simultaneously having it connected to the emissions test machine.

yes that is exactly what i'm saying.

cant you just put run it real hard, exceding 100+mph for few min to burn off excess engine build up?
it should clear it up a bit

i also heard of adding a pure alcohol in gas tank prior the test

all muscles are fixed this way

Okay, I understand.

Your post makes sense and I could now kick myself for not checking my lambda setting AFTER the new-CAT AND before my second emissions test. Of course, with this being a feedback-control-loop I should have expected the lambda settings would change with the new-CAT.

I'll put my head under the bonnet later today and let you know how it goes.

P.S. Can anyone direct me to where I can purchase the appropriate oscilloscope monitoring tool for making the lambda adjustment, as I'd like to be able to start making this adjustment with a scope instead of a voltmeter.

I've tried calling a few merc repair shops to see if I could find someone with a scope to make this adjustment more accurately for me, but they ALL want to go thru their own diagnostics tree, which I'm not interested in paying for.

PPS. Are the scopes connected in the same manner as the voltmeter (X11-3 pin to ground)? If not, what is the connection protocol?

Thanks again.

Attached is my test procedure and results. When I first started the vehicle, before making any adjustments, I received voltages of 7.4 - 8.6 (approximately 31 - 41% duty cycle calculated from voltages).

What's odd is that I had to turn the adjustment screw CCW in order to move duty cycle back close to ~50% (and reduce voltages to 6.5 - 6.8), and I was expecting to have to do just the opposite, as with the excess O2 in my emissions readings, I was expecting the system to be extremely lean, and therefore have to increase voltages.. But it seems from the measurements that either everything in my system is backwards, or that my system was actually running rich.

Also, I did finally read the manual for my Craftsman Digital Multimedia and found that I can measure duty cycle directly without having to convert from voltages. So I measured both voltage AND duty cycle, and as you will see in the attached results that my calculated-duty-cycle-from-voltage didn't always equal my multimeter measured value for duty cycle.

I reset the mixture again today after taking the car on a hwy expedition, and ended up having to enrich the mixture as was predicted earlier in this thread. Duty cycle is now set at 45-48% and the car purrs in idle.

Took vehicle in for CA Emissions Pretest [guy only charged me $10 bucks] and the CO2 and O2 are back to more normal settings, but I continue to fail at NOx, which was even higher than last time. Here are the latest results.

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


Any other thoughts from the forum experts where I should look next? Why did CO drop so low after enriching the mixture?

The engine is reaching about 110C in those shop conditions during the test, which is about 15C higher than anything I see on the road - city or hwy.

Are you sure the fan clutch is working properly? Does the test station have a fan you can direct at the radiator?

-J

I have not tested fan clutch, but fan does run at approximately 107C.