2000 ML320 Failed Emissions

My brother has a 2000 ML320. It is in for Pennsylvania inspection, and for whatever reason the emissions diagnostic test failed. The mechanic said he has to drive it for a while so something can reset,
or eventually pass.
Is this true? Is there a fix?
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Il Tue, 04 Oct 2011 17:27:14 -0400, Justin ha scritto:

Sure. The suggestion is correct: drive it for a while, possibly on highway, at high rotation speed of the engine. The "filter" of the exaust system needs cleaning, probably, but the electronics only allow the process while using the engine at high speed and high power. It's quite common here in Europe. No extra action is usually required.
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Assuming the car has been driven normally, then no, there should be no need to drive it more to get the emissions correct. The whole point of emissions controls is for them to be working all the time in any kind of driving.
Was any work done on the car, eg replace an emission sensor? If that's the case, then having to drive it makes sense. The onboard computer logs certain emission systems parameters and if they are working correctly, it sets flags saying they are OK. It takes some period of driving for all of those flags to get set. And when you take it for inspection here in the USA, they hook eqpt on to the car computer that reads those flags and they must be set to pass. Actually, here in NJ with a late model car you can have one flag that is not set and still pass. Not being set does not mean there is a problem, it just means the computer has not logged enough data to validate that particular emission system is working.
So, let's say you brought a car in and it failed because the computer was reporting a problem in the fuel evap system. The mechanic found a leaking gas cap and replaced it. He can then clear that trouble code, but the emission monitor will not set the OK flag you need to pass inspection until it sees enough data that the system is working OK. That requires just using the car in normal driving. Most of those monitors get set within minutes, but some, like the fuel evap system, require days. It's also not clear exactly what sets that one, ie if it's hours of engine operation, miles driven, start/shut off cycles, or some combination.
So, bottom line, if work was done to fix a problem, then what he was told makes sense. If not, then it makes no sense to me.
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Il Thu, 06 Oct 2011 08:05:29 -0700, snipped-for-privacy@optonline.net ha scritto:

WE're talking about a 2000 car. I mean, a year 2000. I remember that for older cars (and anti-pollution equipment and regulations) the electronic system is a little bit less... evolved (complicated? :) ). So, I presumed it didn't run thoroughly the anti-clogging (diesel) or catalytic regeneration (gasoline) cycle. That's where my statement that the suggestion to "drive it on a highway" makes sense. Interesting information, in your post, however.
You might know that here in Europe we have several different levels of emissions measured, according to numbered standards. Euro1-2-3... we actually are on 5, waiting for level 6 to be disclosed. This in fact is a "commercial" numbering system: the actual standard have some over- complicated numbering systems... For example: http://www.hymerclubitalia.it/euro.html
The page could be titled, in english: which euro corresponds to my vehicle? Especially interesting the last table... ;)
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/ The same basic emission monitors are part of OBDII that went into effect in 1996.

I don't know of any mechanic here in the USA that when presented with a car that had been in routine use that has failed emissions would tell them to drive it on a highway as a solution. For example, the catalytic converter should function and meet emissions standards whether driven in the city or on a highway.
Interesting information, in your post, however.

Here in the USA many states don;t measure emissions at inspection directly. They just use the information from the cars computer that shows the systems are working.

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Il Thu, 06 Oct 2011 14:07:08 -0700, snipped-for-privacy@optonline.net ha scritto: --------- Here in the USA many states don't measure emissions at inspection directly. They just use the information from the cars computer that shows the systems are working. ---------
Well, here in Italy we only measure the final result (i.e. emissions are controlled, no electronic is connected to the car).
And for euro 2 it might happen that you are being checked in a "not favorable" moment (if I can express myself in this way). Since you are asked to maintain the car with emission levels comparable to those declared when it was coming out of the factory (and not better...), you only need to drive it for a while, to obtain a (possibly, if nothing is really wrong) correct emission level. As a matter of fact, Euro 2 standard only measures emissions with engine in "standard working conditions" (the original standard was based on levels measured in controlled conditions, with tests run in engine test room).
I own a euro2 VW (Polo, gasoline, converted to LPG) of the same age of the ML320 of the OP and this happened to me at the time of the second check (2005). Simply driving it 5 km on the high speed ring around the town was enough to obtain a substantial reduction of emissions. After LPG conversion, I know I need to drive for a few kilometers using gasoline, in order to obtain a correct measurement: it's a sort of "reactivation" of the catalyzator. If I just drive to the test station running LPG and switch to gasoline there, for testing, the result is that the catalysator is running poorly and emissions are too high. It's a fact, but don't ask me why... :)
Of course, this doesn't mean anything at all, for the USA! :) It's just for... well, general information? :D
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Interesting and I see your point. Here in NJ they used to check the actual emissions too. First, in the 80s, it was just a check with the car idling. Then in the 90s, the federal EPA ordered states here in the northeast to do more stringent testing that included running the car at highway speeds on a dynamometer while measuring the tailpipe emissions. Christie Whitman was governor at the time. Instead of fighting this nonsense, she lamely went ahead with it. It cost $500mil+ to outfit all the state inspection stations with the dynamometer and new eqpt. There were cost overruns, screw up one after the other, nothing done on time, hours long lines at inspection, etc. That system was used for about 4 years, after which the EPA ok's using the OBDII computer data from the car instead. In other words, they scrapped all that $500mil eqpt and just hook up a cable to the OBDII connector under the dash.
That shows you the malfeasance and incompetence at the EPA. Surely they were already working with the car manufacturers to use OBDII at the very time they insisted that all that money be spent on a system that would be gone in a few short years.
I don't know how Pennsylvania, the state in question, does emission testing.
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Il Fri, 07 Oct 2011 05:40:42 -0700, snipped-for-privacy@optonline.net ha scritto:

That's what we do, now. But the dynamometer is being used to test brakes. Which seems to be correct, imho. Together with a phonemeter to test horns and a light measuring system for headlights. Operator eyes to test all the other lights... :)

Do you know the proverb? Bad thinking is sin, but usually true: briberies?

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That brings up another interesting inspection thing here in NJ. They used to test many things:
brakes headlight aiming windshield wipers horn emissions at idle front suspension, eg ball joints (they actually lifted the car and the guy would try to rock the wheel by hand)
Then in addition to that, in the 90s they added the dynamometer thing to test emissions at highway speed.
Then starting around 2000 they got rid of just about all of the above. I'm actually not sure if they test anything other than brakes and emissions, the latter being done by connecting to the OBDII on the car. They might check lights for working, but the aiming part is long gone. So is the front end check and I don't remember hearing any horns blowing either. Next time I'm there I'll pay closer attention.
Oh and new cars no longer need to be inspected for 5 years. No more inspections on motorcycles. Oh my, maybe we're all gonna die!
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Il Sat, 08 Oct 2011 05:21:05 -0700, snipped-for-privacy@optonline.net ha scritto:

:D I don't know how we could drive such uncontrolled cars, in the '70s and '80s... I'm a survivor!!! :D
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I forgot the best part. In addition to motorcycles, diesel cars older than 1994 or 96 no longer need to be inspected here in N J at all. I won't have to take the 80 300SD for inspection ever again!
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It is 1996 or older diesel cars in NJ doesn't need inspection... just peel of those inspection stickers... whoohoo!
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Pennsylvania inspection is done by private garage that pretty much only does inspection.... or was it PA facility... It has been a long while when I did it. They had a RPM meter that they wanted you to raise the engine RPM to 2000 while they take emission reading. Other stuff is safety light... and that was it. It was not as comprehensive as NJ.
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As I pointed out earlier, I don't think there is much safety related in the inspection here in NJ anymore either. They used to check brakes, front end joints, wipers, horn, lights, headlight aiming, glass for cracks, etc. Now for sure the front end joints and headlight aiming are gone. I'm pretty sure even the lights working are done too. When you drove up they used to ask you to turn on hi beams, low beams, left turn signal, etc., one at a time, I know they don't do that anymore, but it's possible they are doing it when the inspector moves the car through the line. Next time I'll watch more closely, when I take my other car in. But I know I have not heard horns blowing anymore either, so I suspect all that is gone. You used to have to get even new cars inspected every year. Now new ones are good I think for 5 and others every 2.
Only things I know they do for sure is emissions via the car computer and brake test where they hit them while rolling across a test pad at about 5mph that shows the force on each wheel.
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Don't know if this is true on a Mercedes but, if a trouble code was recently cleared by an OBDII reader, the car has to driven both highway and street fo rabout 50 miles for the sensors to reset. Had it happen to my Ford Explorer recently. My E350 4Matic is too new for a problem like this to occur. (I hope) On Tue, 04 Oct 2011 17:27:14 -0400, Justin

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It's actually the other way around. It takes a certain amount of driving to SET the emissions monitors after they have been cleared. Most of them set within 15 mins or so of driving. The most notorious is the fuel evaporation system which takes much longer to set. No one seems to know exactly what it takes to get it set either, ie is it highway driving, stop and go, either, engine run time, etc. Also, I don't understand why it would take so long as my understanding of what it's looking for is maintenance of a certain pressure in the gas tank, which indicates that there are no leaks to allow vapors out.
Here in NJ you can pass the state emissions test with a recent vintage car with 1 not set. With an older car, I think they may allow 2.
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