My friend just purchaised '91 Fierbird 3.1, MT5.

As usually we replaced TCP, MAP, EGR and Oxy Sensor.

But engine runs rought, code 13 (Oxy sensor reads lean at crusing speed), so the quation is why this code appeares with new oxy sensor. What to check.

BTW. Someone, please help me to get engine controll wiering diagrams and sensor parameters.

Thanks!

 

as a rule basically all sensors are about 1-5 volt except for 02 which is 0-1v

anyways though it sounds like a vacumm leak. If the engine is running lean and sensors arent able to counter it then youre finding an extrra way to get air in the engine which shouldnt be there. Check all vaccum fittings double. i'd also replace the fuel filter if it hasnt been done as that could also be the problem.

Not sure if you'rs is map or maf but if maf double check your intake tubing to make sure its tight with no leaks and no holes after the mass air flow sensor.

If map make sure its plugged in and the vaccumm line is securely in place.

 

May be Vac. leak, but spurk plugs are black, Fuel/air mixture is reach....

 

With the engine running that rich, there are a couple of things to check:

injectors may be leaking and/or bad

fuel pressure regulator may be passing fuel via the vacuum hose (pull like while engine is running and check for fuel coming out of port on FPR)

the charcoal cannistor may be fuel logged

RBob.