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  #1  
Old 11-28-2003, 05:58 PM
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Smogging an 87 300E

By scouring the archives I've determined that the easiest way to make smog here in California (I'm very close) is to keep my cat really hot before the test.

HC
MAX... 110, MEASURED...121 @ 15 mph
MAX...85, MEASURED... 84 @ 25 mph

My CO meaasurements are quite low.

Since my HC number is slightly high can I cure that by using a hotter plug? Any other suggestions would be welcome. Has anyone used that additive that guarantees one to pass the test? And is the static test easier than the load (dyno) test? Many thanks in advance.
Thom
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1987 300E
1967 Jaguar E-type Series I, 2+2

Last edited by Thom Pintello; 11-28-2003 at 06:21 PM.
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  #2  
Old 11-28-2003, 07:16 PM
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Thom, If your fuel mixture is set properly and the vehicle is in good service ? Replace your catalytic converter, those magic pass smog juice only work marginally. Don't install hotter plugs , Mercedes has the compression,timing,temperature, and many other factors designed to work with the stock plug. Dyno testing is easier to pass only if the vehicle is dirty at idle. It is harder to pass because they measure NOX. S.
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  #3  
Old 11-28-2003, 07:42 PM
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Quote:
Originally posted by slewman
Thom, If your fuel mixture is set properly and the vehicle is in good service ? Replace your catalytic converter, those magic pass smog juice only work marginally. Don't install hotter plugs , Mercedes has the compression,timing,temperature, and many other factors designed to work with the stock plug. Dyno testing is easier to pass only if the vehicle is dirty at idle. It is harder to pass because they measure NOX. S.
Thanks slew. I intend to replace the O2 sensor for the long term as that would probably dial in the air-fuel mixture. As I'm very close I want a quick short term fix to get me past the test. I'm just hoping that keeping the catalytic converter hot before the test will do the trick.
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1987 300E
1967 Jaguar E-type Series I, 2+2
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  #4  
Old 11-28-2003, 09:42 PM
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It would help if you would post all measured numbers including CO and 02 if you want a meaningful analysis and suggestions.

OE spark plug heat range is fine and snake oil additives are unlikely to have much, if any, effect.

Recent threads on this issue have included analysis of typical numbers and what to do to keep the converter hot prior to the test.

Duke
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  #5  
Old 11-28-2003, 10:27 PM
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Duke,
Here's the rest of the measurements...


15 mph CO2% 14.9, O2 0.1 HC(ppm) MAX 110, AVE 31, MEAS 121
CO% MAX 0.71, AVE 0.10, MEAS 0.24
NO(ppm) MAX 772, AVA 237, MEAS 652

25 mph CO2% 14.9 HC(ppm) MAX 85, AVE 20, MEAS 84
CO% MAX 0.59, AVE 0.09, MEAS 0.17,
NO MAX 711, AVE 199, MEAS 344

Thanks.
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1987 300E
1967 Jaguar E-type Series I, 2+2
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  #6  
Old 11-28-2003, 10:31 PM
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I hate to say this because it sounds fishy - but I think "Guaranteed to Pass" actually works. I don't know how it works but I seriously think it works. Someone had told me it worked for them so I skeptically tried it, and it worked. There was no possible other explaination for passing easily after failing rather badly.
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  #7  
Old 11-29-2003, 01:25 PM
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Somewhat typical of 103 engines, but worse than usual on HC. The CO indicates the basic mixture setting is okay, and the 0.1 % percent O2 indicates that the HC could probably be brought a little below the limit if the converters were hotter and consumed that last little bit of O2 to oxidize HC and CO.

A couple of threads in the last month or two have similar discussions of six and V-8 emissions from this era models. The sixes tend to be "dirtier" than the V-8s.

My suggestion would be to get the car retested. Go to a drive through place when the line is short and keep the engine at 2K revs prior to turning it over to the tech. Make sure the car has been driven at least 20 minutes in the city before having it tested, and it is preferable to have a freeway jaunt.

Have it tested on a rainy day and ask them to run the "tire dry test". This will heat the converters up a bit prior to beginning the 15 MPH test.

One thing you DO NOT want to do with a 103-engined model is just drop it off at some smog check place and pick it up later. You need to "manage" the way the car is tested, with particular attention paid to having the converter as hot as possible prior to the test.

In a recent thread an owner threw a lot of money at the car - new converters and O2 sensor as I recall, and passed the test, but not by much. I felt he could have passed by properly managing the test using the methods I mentioned above. It would have been a lot cheaper.

Duke
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  #8  
Old 12-09-2003, 04:50 PM
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Thumbs up Passed!!!!

OK guys, I did a re-test and passed. I did three things to get myself over the hump on this...#1. I took out my spark plugs and cleaned them with a file. It had to have a slightly cleaner spark, correct? #2. I put a bottle of "CRC Pass or double your money back" injection system cleaner into my gas tank as per their instructions. #3. I managed the test by keeping my revs up prior to the actual 15 and 25 MPH dyno tests. This kept my catalytic converter hot which burned up those hydrocarbons that bit me in the butt during my first test. And the result? In my first test I had a reading of 121 for HC but the maximum allowed was 110. On my second test my HC reading an easy 82. So the old 300E passed with flying colors and I didn't have to spend money on expensive repairs!! Thanks to all for their contributuions to this thread as it was a lifesaver.
Thom
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1967 Jaguar E-type Series I, 2+2
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  #9  
Old 12-09-2003, 07:06 PM
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on my M103, I found an exhaust leak had caused the problem. prior to that I was getting I think a 131 out of a 126 on HC. after that I was about 30. NOx also declined similarly. I don't have the numbers in front of me though. Even a tiny air leak will totally mess up the emissions system.
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