I have a 1988 Volvo 740 GLE. I am up for emission soon. The car mpg is very poor in city dirving something like 15-17MPG in city driving or sometimes worse. But on the highway, it does 20-23MPG.
I replaced O2 Sensor, Fuel pressure regulator, Cleaned the throttle body, changed Air filter, Flame Trap, Distributor rotor and cap. I have changed the car's AMM [from the JunkYard], the engine temperature sensor which sets on the engine block [again junkyard part], the ignition coil, the ignition wires, and the Fuel filter but all of this never did me any good. It seems to be just staying at this MPG. I think I have listed here all the parts that I have changed.
I checked at fueleconomy.gov and found the EPA estimated MPG for my car and it was 20 City and 25 or 26 Highway. Definitely, I am way under the estimated city numbers.
Also, my service light gets on when I start the car and stay on for 60 seconds or so and then goes off. Since I owned the car, I was never able to reset that light. Does anybody know for this particular car year and model how to reset the service light. Also, does this specific car have a check engine light or not?
I think I won't be able to do the test unless this light is off. They won't test the car, right? Does anyone have any idea or suggestion for me before going to emissions?
I will probably change the spark plugs and definitely the oil. I will also try to use some Fuel system cleaner in the gas tank. I was once advised to use the Ultra i.e 93 Unleaded fuel not regular 87 when going to emissions. Does that really matter.
I am in Maryland.
Thanks very much for reading the post and for giving me any suggestions.
--Hameed.