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Discussion Starter #1
Hello

I just failed the California Smog emissions test with my 1987 300E

HC and NO were high

see results below


any ideas on where to start, I just changed the plugs, wires, cap and rotor and an oil change before the test
 

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W201 Moderator
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You will need a new oxygen sensor and a catalytic converter as a start.
Those alone will bring down your values significantly (like 40% - 60% assuming the ones you have are shot, they look like it)

If it still does not pass the 15MPH but passes the 25MPH test that is because the CAT is not hot enough for the first test. Second one (25MPH) will always do better.
Find a test center that is willing to preheat the CAT before they start the testing. Basically you need to be on the rollers and do a dummy 15MPH test before they start the real testing sequence.

How much oil is this car burning?
 

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Isn't the car emissions exempt for the year?
In Texas cars older than 1994 are exempt along with all diesel models.

Jetdude
 

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Will send you a PM Fredzrez. Pretty sure you will need a new O2 sensor and a Cat assuming the Cat is original and the O2 sensor has many miles on it and probably a lot of soot as well.

BTW your last test was botched. The CAT was not hot enough when the 15mph test was done. You can see how much better the 25mph turned out as the CAT warmed up. It would have failed no matter what though.
 

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Discussion Starter #6
Hi Everyone

Just wanted to pass along an update.

I changed the CAT and the vehicle passed smog today. NO way down, HC is down as well but still a bit high.

Still pan to change the O2 senor, it is super tight, multiple applications of PB blaster, will try to remove in teh next day or two if still tight will have someone take a torch to it.

Thanks to everyone for their input and suggestions.

2603248
 

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Good to hear! You went down the same path I did a couple years back. Same story with mine CAT made it pass, about 3 years back. And passed again last year.

Congratulations! You numbers look like you will probably pass in 2 years again.

- Cheers!
 

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Good to hear! You went down the same path I did a couple years back. Same story with mine CAT made it pass, about 3 years back. And passed again last year.

Congratulations! You numbers look like you will probably pass in 2 years again.

- Cheers!
dolucasi - thank you for sharing your experience and all your knowledge and advice.

I was on the fence, considering to salvage the vehicle, but your enthusiasm inspired me to hang onto it.

Thanks again!
 
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fredzrez
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