I agree that those are some tight HC tolerances. For reference, here is the test conducted annually in Harris County Texas (Houston) that I had done last week. In the 6 years I've had the 300E, these are the lowest readings I've seen.

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

Those are very good numbers for a M103. The NOx leads me to believe that the timing map is retarded, but like most KE fuel system models, HC is high relative to the other emissions.

Does your engine have EGR?

I can't make any sense out of the O2 readings. Air has about 20 percent O2 and the exhaust gas should have near zero. In CA the O2 readings are given percent and an efficient catalyst will yield 0.0%. If it's more, like 0.1% or 0.2% the cat is not working at maximum efficiency, often because it is not hot enough.

One tenth of one percent is 1000 ppm, so even if the reading is 0.0 percent, there could still be enough O2 in the exhaust (a few hundred ppm) to promote more reaction if the catalyst is hotter, and this will reduce the HC number.

I wish the O2 readings were in ppm.

Duke

HC is raw fuel. WHen you have to much air to fuel ratio, it can cause you to fail on the HydroCarbons. On newer mercedes and BMW's i've heard the Bosch Air Mass Meter has been a common culprit to high HC's, due to its premature death, but this is only what i've heard.

Below is the HydroCarbon break down from http://www.Aircare.ca they are the emissions company in BC. The company is under Translink control, however it is run by For Profit American company " ESP " under its Envirotest Canada division. In all ESP runs 80% of the emissions testing programs around the world. So all information you'll find under repairs on this site will directly relate to all emmisions programs.

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Possible Causes of High Hydrocarbon (HC) Emissions
Hydrocarbons relate to unburned fuel. You may logically think that must mean that the engine is getting too much fuel. However, that is only one of many possibilities ranging from fuel problems, to electrical problems, to internal engine problems such as piston rings that can cause HC emissions to be excessive.

In order to pinpoint the cause of excessive HC emissions, the following systems (if applicable) will need to be checked, usually in the order shown below:

Lean or Rich Air-Fuel Ratio
For an engine to operate as designed, the correct ratio of fuel to air must be delivered to the cylinders. If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons. If the fuel system is too rich, it also may result in high HC but will be accompanied by high CO as well.

For more info regarding the diagnosis of fuel delivery systems, see Fuel System Testing

Inadequate Catalytic Converter Efficiency
For vehicles that are 1988 model year or newer, it is very important that the catalytic converter be operating at 90% efficiency or better. That means that the emissions that come out of the tailpipe must be no more than 10% of what goes in.

For more info regarding how to determine catalytic converter efficiency, see Catalytic Converter Testing

Induction System Problems
There are many aspects of the engine's air induction system (hoses, intake runners, intake manifold, vacuum-controlled devices) that can cause disruption in the air and fuel getting to the cylinders and result in high HC. Incorrect PCV valve/orifice flow rate can also cause similar symptoms. Leaking EGR valves also may cause excessive HC emissions.

For more info regarding how induction system problems are identified, see Induction System Testing

Poor Ignition Performance
Ignition defects including dirty spark plugs, leaking or open-circuited spark plugs or wires, or defective ignition coils can all result in a shortage of spark energy. Any shortage of spark energy may cause high HC emissions.

If the spark occurs at the wrong time, incomplete combustion and high hydrocarbons may result. Too much spark advance could be due to an incorrect adjustment or a defect in mechanical or vacuum advance mechanisms.

For more info on testing ignition systems for inadequate spark energy or incorrect spark timing, see Ignition System Testing

Uneven Output Among the Engine's Cylinders
At this stage of the diagnosis the technician should be sure that the air-fuel ratio is correct, there are no external vacuum leaks, and the ignition system is operating normally. There are still many possible causes of high hydrocarbons, most of which are either internal engine problems or tough-to-detect induction system problems such as valve deposits or a leaking EGR valve. On fuel-injected vehicles, poor fuel atomization is a common cause of HC problems.

For all of these remaining possibilities, checking for uneven power output amongst cylinders will usually help to track down the cause of the problem. For more info on testing for uneven power output, see Engine Integrity Tests

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I do not know the details of the diagnostic. I left the car at the shop, and I was not present for the testing, etc.. I guess I could phone the shop and ask him about the "combustion flush".

I was so happy to see the "pass" report, I just wanted to get out of the shop real fast, to get my new license plate sticker.

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1989 420 SEL

am sure your specialist manipulated your emission settings for your car to pass the test - he did not fix the problem. it takes more than 200 bucks to fix emission related problems.

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joel

Prayers bring forth enlightenment.

Joel you're so right. It cost's much more then 200 dollars. Also the Drive Clean program in Ontario is a private program run by certified shops using the ESP technology. Some of my family members have told me how they buy fraudulant tests in Ontario with their old beaters mostly used as work commuters. If their car fails, they go back to the shop towards the end of the day with a similar car that's in mint condition, weighs around the same and the mechanic punches the car in as the failure car...in exchange for a little payment under the table. Obiously the ghost car will pass fine, and your beater now has insurance. That's the main fraud i know lots people that are using in Ontario. Usually a proper emissions repair costs on average around 500-600.

In BC I know this guy in Port Coq., and if your mercedes fails the Emissions test, all he does is retards the timing for you and your set. For a little bit more money he'll put it on the scope and check the readings first and you're almost guarenteed to pass with his first adjustment. Go back and he changes it back to normal. I think in this case, this is what the mechanic did to this guys car, passed him, and charged him all this free money and laughing all the way to the bank.

p.s. Look to see if their's a hole in you're cat. Some mechanic's have this myth, that if you drill a small hole in the cat, it'll suck enough air in to dilute the readings. If you have to big of a hole, its going to say sample dilution and they won't be able to test you.

I, for one, and I think others would like to get an explanation.

Unless you get to the bottom of what happened you're probably going to have to go through this drill every time.

I'm very suspicious of what really happened. You should be too.

Duke

Duke, yes my M103 has EGR system. As far as the timing being retarded, I don't know ... I'm getting approx 19mpg in city/hwy driving.

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

Duke 2.6

F.W.I.W. here in Ontario ( where " Cigar Havana" is ), there is always a " Conditioning Mode ". This is a No-Load run for 2 minutes, before the actual test begins.

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2007 C 230 Sport.

Conditioning Mode for 2 minutes is interesing. ESP the designers of the testing software suggest that Conditioning beyond 1 minute is considered fraudulent testing. As this helps heat the cat up and you're beggining the test right away. Conditioning for 2 minutes and still failing...well then you know the car is hopeless and also its an inaccurate test in the customers favor. Drive clean seems to have its own issues...

Attached is a recent copy of Oregon DEQ test result for a 1992 300CE that I recently purchased. I have done nothing to this car. Carfax showed some failures to pass emissions and at one time labled the car a "gross polluter" in California, whatever that means. The car was run for 1/2 hour before testing and not turned off. It was NOT done on a dyno. The car passed but I think that the HC numbers were high and an wondering if this is normal????

118,000miles ; about 45 deg F outside temp

Attached Files

File0001.PDF (60.1 KB, 141 views)

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1994 E320 Cabriolet
1992 300CE (Sold)
1991 300SE (Sold)
1986 560SEL (Sold)

Oh, that's certainly worth something. In CA the only "conditioning" is the tire dry test if it's wet. Conditioning is a HUGE DEAL that the CA test authorities don't want to address. At lot of cars fail simply because of how they are conditioned, which is not uniform. There is no conditioning standard, and this makes it easier for unscrupulous operators to commit fraud by testing a clean car whose catalyst is too cold.

IMO all cars should be reasonably conditioned as part of the test so there's some basis for comparing results.

Our Mercs tend to be high on HC, and the limit keeps tightening even as the cars get older and should have more wear allowance. They can also be very low on CO and NOx. You can have very low CO and NOx, but if only 1 PPM above the HC limit, you FAIL. That's why I don't feel any guilt if I have to diddle my timing map a little to get more margin.

The government has run amuck. When are people going to stand up and say ENOUGH!?

Duke

A little knowledge is said to be dangerous.

F.Y.I. ,I was instrumental in setting up the AirCare System in the Lower Mainland, back in 1988/89.
I'm also familiar with the " Weak Points " of todays AirCare procedures.

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2007 C 230 Sport.

It's not so much the government, as at is the Treehuggers.
Never met one to this day that has ANY knowledge about cars, much less how automotive emissions are created.

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2007 C 230 Sport.

When the government is driven on technology issues by people who don't understand technology, then the problem is the government. And in my experience, few in government who establish and enforce the various emission control/test programs understand the underlying science and technology.

Duke