Ok here is the low down on my car. I own a beautiful 1991 Formula 350. The problem is that is look great but does not run all to well. I live in Ca and had to take my car to the referee smog station. It failed misserably My HC's were over the top and my CO(%) was way high too. the wierd thing is my NO(PPM) was extremely low, at 15mph it measures 77 with an allowed max of 797, and at 25 mph it measured 80 and the max allowed is 706. I am not sure what is going on with this car. After it failed i took it to the local Pontiac dealer and had them do diagnostics test on the car. when i returned to pick up the car they told me that they didnt do anything to it and it passed smog on their machine. i returned to the smog only station and it passed barely.


Ever since the car does not idle corectly. the idle now fluctuates between 300rpm-700rpm in gear and out of gear it does the same thing but at a higher rpm. I just changed the sparkplugs and cap and rotor. Today i replaced the O2 sensor and that wasnt it.

something that caught me off guard is when i had the O2 sensor unpluged i had to start up the car to move it and the check engine light did not come on. I thought if the sensor was unpluged the light would come on.

If anyone has any ideas i would greatly appreciate them. sorry for such a long post.

Thanks

 

The check engine light won't come on if the O2 sensor is unplugged until the engine reaches N.O.T. Have you checked for vacuum leaks?

 

have not checked for vacume leaks, i can check though. thanks ill get bak to the forum with my results

 

did you let it warm up before you took it to emmsions when it failed the first time

 

yes the car was 220 degrees it passed the current problem i have is the idle is all out of wack. I checked for a vacume leak today and i did not find one. The main problem now is that the cars idle is all messed up it Fluctuates about 300-400rpms in gear and out of gear. some times it stalls when i stop or attempt to accelerate from a stop.


Thanks