I failed the emissions test on NOx. Allowed NOx was 200 and I failed with a 219. I want to inspect the EGR valve but can't find anything that looks like an egr by the intake and out mainfold.

Called 2 MB dealers for a price quote for egr on '87 2.3 190e, both said egr is on the 2.3. But I don't see one. The Haynes manual for the 4 cylinder engines do not even talk about the egr.

Can someone point out where it is, want to replace it for a reinspection.

The 190E 2.3 didnt have EGR in the USA until 1991.

What were the OTHER readings like O2, Hc, & CO?

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks for your update. The readings from the emissions test was:

HC Limit: .80gpm Actual: .65 Pass

CO Limit: 15gpm Actual: 4.11 Pass

NOx Limit: 2.00 Actual: 2.39 Fail

Before going back for my emissions test, what can I do to lower the NOx? Any help is appreciated.

You're between the proverbial rock and hard place! NOx control is accomplished with the three way catalyst. Precise fuel-air ratio control provides an exhaust gas consituency that is required for a TWC to both oxidize HC and CO and "reduce" (breakdown) NOx into nitrogen and oxygen. The oxygen molecules from disassociated NOx are also available to oxidize HC and CO.

Converter temperature is a big issue in converter efficiency, and the hotter the better. Higher EGT and higher converter temperatures can be had by retarding the ignition timing. Retarding the ignition timing also reduces peak combustion temperature, which should reduce "engine out" NOx emissions. I believe you can do this by adjusting the distributor on the 102 engine. Retard the timing at least five degrees from spec. The initial timing spec should be on the emission/tuneup decal in the engine compartment. What is it?

In CA the timing is supposed to be checked as part of the emission test and the car failed if it is not to spec. If no acceptable range is provided by the manufacturer, CA established 3 degrees advance beyond spec as the limit, with no limit on the amount of retard from spec.

All the 102 and 103 engines tend to show higher than average emissions for their year group. In CA the 103 had been identified as a "high emitter family" and they are usually on the ragged edge of HC, but NOx is not generally a problem. Unfortunately, the initial timing cannot be adjusted on the 103 engines, but the rate of advance can be slowed by varying a resistor value, which should be of help since CA tests are done on a chassis dyno at 15 and 25 MPH. Our emissions are measured in PPM, and the "cut points" are arbitrary as the cars were certified to an abolute grams per mile standard.

NY may have similar issues as the GPM cut points are probably not the same as the full EPA certification GPM limits, but are arrived at through a statistical analysis process that is essentially designed to fail an arbitrary percentage of cars.

Emission testing has as much to do with politics as it has to do with technical issues and clean air!

Duke

Duke

You got most of it right except this one.
It has EVERYTHING to do with politics, aside from being a great cash cow!

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2007 C 230 Sport.

Went back for my 3rd emissions test and passed with flying colors but I'm puzzled. Today's readings were so much better than the previous test.

HC Limit: .80gpm Actual: .65 Pass
CO Limit: 15gpm Actual: 4.11 Pass
NOx Limit: 2.00 Actual: 2.39 Fail

Today's result's were:
HC Limit: .80gpm Actual: .12 Pass
CO Limit: 15gpm Actual: 1.8 Pass
NOx Limit: 2.00 Actual: .55 Pass

Before the reinspection, I 1). added Techron to the gas tank, 2). changed the oil and 3). poured 6 oz of concentrated Gumout fuel injector through the air flow sensor into the throtle valve housing and let it sit overnight. And the spark plug tips were greyish to brown which means it was normal operating temperature.

Should the above steps have reduced the emissions by that much?

Did you allow the car to warm up more the second time? The cat can tank a long time to reach full operating temp, especially with low outside temps. I usually drive my car at least 1/2 an hour on the highway before testing.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Actually the car warmed up longer on the test that I failed. I'm aware the cat should be hot to burn off the gases but I dropped off the car after a short drive and they took it in within 30 minutes.

Just glad I passed.