Emission test

Joined
11 January 2024
Messages
6
Location
Tx USA
1991 stock with 53,000 miles, fails NO @ 15 MPH, passes everything else, including NO @25 MPH. Any solutions?

Thanks for any information.
 
That is kind of short on details. Depending on how big the 'fail' is, making sure that the car is tested while the catalytic converters are really hot can help. Your car appears to have non stock wheels. If the rolling radius is larger than OEM this will reduce the engine RPM at 15 mph which can alter the amount of EGR that is being applied.

Other possible causes include
- partially clogged EGR
- the catalytic converters are getting tired

If you are close to compliance and have good margins on all the other measurements the catalytic converters are probably OK. The favorite 'first step' is to drive around enough to make sure that the catalytic converters are hot and then try and have the emission test caried out right away while they are hot.
 
yea get those cats warmed up
 
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