Emisions?

Joe90SC

Registered User
I have a 1990 SC and just recently took it through emisions but it failed on the Oxides of Nitrogen but not by much. I have never had a problem in the past. Should I just run it through again or is their something I should do. Any info would help.

Thanks,
Joe Russo
 
Joe,
High NOx results from excessive combustion chamber temperature. If you aren't failing by too much, there are a couple things you can do that might give enough improvement to pass. First, retard timing by pulling the octane jumper, and second get some high octane fuel. If you can get 94 that's good, or maybe even mix in a couple gallons of 100 octane unleaded race fuel. I think Sunoco even sells that at some service stations on the east coast.

BTW I don't know about MD, but here in CA you are labeled a "gross polluter" if you fail twice, so it's important to get a pre-test to make sure you will pass the second time!
 
NOx failure

NOx failure
I just replaced my O2 sensors and it made a 23% inprovement
on the NOx test run at 25mph, which was just enough to get it to pass. This was the first time I have replaced the O2's.

I have a stock 1990 SC with 170k, with aod Lentech tranny.
 
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