Air/Fuel Mixture: Adjustments

The air fuel mixture is not adjustable. If you suspect a problem with the mixture check for the following:
^ Fuel pressure too high
^ Fuel injector(s) leaking
^ Condition of engine oil (gas in oil)
^ Fuel pressure regulator leaking fuel from it's diaphragm into the intake manifold.
If all fuel related components are OK, then check the On-Board Diagnostic System in Computers and Control Systems. Computers and Control Systems