I just purchased a 91 CP and it failed the emission test, with high HC. This car has 67k and is very clean, this reading was 8.4225 when 2 years prior it was .1793 . I ran a can of BG 44k in 1 tank of fuel and changed oil, plugs and PCV. Before I do the retest is there anything else I can do?

 

High hydrocarbon's are usually a sign of running rich. Do you have a way to watch O2 readings? Might have fuel pressure regulator bad, coolant sensor out of range a little, any number of things. Air flow meter comes to mind. Notice any difference in fuel economy? Hard to really say without some scan tool readings.

 

At this time without taking it in , I do not have a way to watch 02 readings. The car has been running hot around 240, even in the morning. Does the coolant sensor have anything to do with that? The fuel economy seems to be good for the car. Do you think I should take it in for a check before I try the test again?

 

I'll leave the technical specifics to the expert mech259, but I do believe that 240* is too hot.

 

No, the coolant sensor doesn't control heat. The CTS is the tattletale for the ECM, and the hotter it runs, the more the ECM fattens up the fuel mixture to try and cool it down. I believe you are on the right track with the hot engine if your gauge is right. [8D]

 

Thanks for all the advice. I noticed today that my lower fan is not running. Is there a senser for each fan or 1 that works both? The book does not show where it is or what it looks like. How can I test the fan to see if it is working?

 

The cooling fans both have relays that are controlled by the ECM based on inputs it receives, such as engine temperature, a/c request, etc.... The front fan is basically a condenser fan for the a/c. I uploaded a wiring diagram for you on the cooling fans. You might have to d/l it and shrink it a bit to print it.[8D]

 

I have an upper and lower fan on the engine side of the radiator and the upper one comes on right away, but the lower one is not coming on. Would this be enough to make the car run in the 240 mark? It does not seem to be boiling over at all. It cools when I am moving and go's back up when I am stopped, but not past the danger mark.

 

maybe its time for a flush or replace the thermostat.

 

Passed Emissions great today, better then last time. BG 44K is some good stuff. However I am still having a heat problem, only when I am sitting in traffic. I climbs close to the red line. When I am moving it runs about 150. I am getting the rad flushed friday but the lower fan I think is still not working. Does this sound like just the fan and not the ECM? or the relay?