1993 rodeo gas milage,black smoke

[rodeoowner]

i just bought a 1993 rodeo, it has 131,134 miles. the o2 light stays on most of the time. i am not getting good milage at all and i just had the oil and filters changed since then it letting black smoke out the tailpip. not alot but it wasnt there before. what can or should i do.

[Doug Rodrigues]

My educated guess is that the oxygen sensor on your exhaust system is defective. That has a bearing on the fuel mixture. Rather than sensing oxygen, I believe that the sensor is in reality, a temperature sensor. Hotter is leaner. Cooler is richer. After thousands of hot/cold cycles the sensor becomes defective. This is a generic answer because I've never worked on a Rodeo before but I think that my answer is probably correct.

Black smoke usually indicates too rich a mixture. Grey smoke usually indicates oil burn. Did you just buy this vehicle off a used car lot? If you did, ANYTHING is possible.