Oldsmobile/Buick Repair: Fuel / Air Mixture Ratio on 90 Buick LeSabre, fuel air mixture, mixture ratio

Question
I am wondering how you would go about leaning the mixture on a 90 Buick LeSabre.  I have failed emissions test multiple times and this is about the only thing no one has tried.  

Answer
Hello Keith,
The ECM does all that adjusting. There is no way for you to do it.

Keeping the plugs, wires, air filter, and EGR valve in good shape should be all that is needed.

Actually, a vacuum leak could cause a lean misfire, which could cause the failure.
The catalytic converter may not be operating correctly either, since it should clean up the exhaust.

Van