TDI EMISSIONS

I just brought my 98 TDI in for its annual emissions inspection. They tested for something called "opacity". The maximum allowable limit was 20%. My car scored 0.7%.
What is OPACITY???????? My car has 30,000 miles.

Opacity is exactly what it sounds like: A measure of the amount of visible light that is blocked by the sooty exhaust of a diesel. In Salt Lake City all cars, including diesels, are required to pass an emissions test. Only one place in the entire city tests diesels, and the only test they run is the opacity test. The standard is 20%, which makes the test entirely meaningless for any modern automotive diesel which is running halfway decent. It's just another example of the government fooling around with stuff they don't understand. I'm sure that in places like California you'd have to pass a "real" emissions test, just like a gasoline engine. The good new is: You'll never flunk the opacity test no matter how old and beat up you TDI gets. At 20% opacity it would be running so bad I doubt you could get it started in the first place.

-mickey

Emission Test for Diesels? How strange. In Atlanta or Georgia for that matter all diesels are exempt from testing forever. Hip hip horahh. We only have emissions tests in Metro Atlanta and test 1975 and newer gas vehicles.

Chow

In northern California, no smog tests for diesel powered vehicles(at least not in Napa County). They are trying to come up with a way to legislate most cars and all diesels from the state. Our tax dollars at work. They are trying to prove that diesels cause cancer. They came to the conclusion that since truckers suffer from more cancer than the general public, then diesel fuel MUST be the cause. Of course, the fact that a high percentage of truck drivers(as compared to the GP) are smokers has nothing to do with it at all.

In British Columbia, the AirScare programme tests diesel engine vehicles. Our old '87 Golf Diesel has 'blown' 0% opacity with the exception of one year where it was 1%...dirty air filter.

Yup, with a 20% limit (same here in BC), the engine will be smoking.

Just another $18 CDN every year for nothing.
Harry.

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'87 Golf Diesel (256000+ Km)
'00 Golf TDI GLS, 5M, heated seats on order

Only $18. I wish we had it so good. They are trying to get our cars tested on dyno's. Also using roadside sniffers. Yet I always seem to be stuck behind some beat up old car that get 50 miles to the quart of oil. Never see a cop pull one of those over, either.

I got a ticket for Excessive Smoke driving my old 240Z one day! I was on my way home from passing my emissions test. Really! I showed the judge the emissions compliance certificate and he threw the case out.

-mickey

Actually, Noel, in California, diesels have been tested since '94-95 or something like that. New vehicles are exempt from smog check for 4 years and then have to be smogged. That means that I have three more years to go before I have to remove all of my 'mods'.

Peter, Well last year my diesel-powered
truck's DMV renewal came with a "smog check required" stamped on it. It also came with a box to check for a smog exemption due to it's being diesel powered. I checked it, and turned in the renewal without the smog certificate. The DMV accepted it. Napa county is smog exempt?

[This message has been edited by N Dennis (edited July 29, 1999).]

If that's the case, I'm moving up there! But San Francisco's weather is so much nicer. I don't know. I'm so confused!

Peter, I guess it is possible that my Powerstroke was able to use the diesel exemption due to it being a truck with 8800gvw. I asked the DMV clerk about the exemption and she indicated that diesels are not smogged. I guess I will find out in 4 years when the Golf is due.

Our opacity test is 6% in the UK. And the gas engine test is really strict! My new TDI (still to come) has a catalytic converter. I know about these on gas engines but are things the same on a diesel?

I do not know if they are identical to the gasoline versions, but they do make the exhaust smell obnoxious. Fortunately the VW TDI's do not emit much in the way of exhaust smell. My Powerstroke's exhaust is much more noticeable and objectionable.

Isn't the wonderful diesel exhaust aroma due to un-combusted or semi-combusted aledehyde compounds which attach themselves to the soot particles in the exhaust? BTW, I'm under the impression that the emission levels from a diesel engine remain fairly constant throught the life of the engine (as opposed to a gas engine which gets dirtier with mileage) -- does this apply to soot as well? And another thing -- who here has the most miles on a TDi motor?

I have owned both diesels with and without cats. Maybe it is not the cat that really makes it obnoxious. Maybe it is the direct-injection process. I do know that the Powerstroke's exhaust smell is harder to take than the 6.9 IDI that I owned before.

You read a lot in the press about how impending emissions standards will be the death of the diesel. Does this mean there will be a TDI museum next to the Studebaker museum?