Can a faulty or stuck open thermostat cause a car to get bad gas milage in the city, but great (normal) milage on the freeway?
My brother's civic gets bad mgp in the city; about 9 gallons to every 140miles, but average, about 26mpg-32mpg on the freeway. This is on a 1994 Honda Civic EX (sedan) automatic, approx 97,000 miles. I have used redline si-1 fuel system cleaner within the past 10,000 miles, and he usually uses chevron gas, which is pretty good.
I have reason to believe that the fuel pressure regulator may be going bad as well, which can cause bad milage or the car to run rich; there seems to be quite a bit of black 'carbon' soot on the tailpipe. Or this could be from a faulty 02 sensor.
I will be changing out the thermostat tonight, the oil, and the tranny fluid as well.
Thanks for any input.
EDIT: I just thougth of something, could a bad PCV valve make the car get bad gas milage as well? The honda one costs $22 from the dealer, and I am having trouble finding it at parts stores.
My brother's civic gets bad mgp in the city; about 9 gallons to every 140miles, but average, about 26mpg-32mpg on the freeway. This is on a 1994 Honda Civic EX (sedan) automatic, approx 97,000 miles. I have used redline si-1 fuel system cleaner within the past 10,000 miles, and he usually uses chevron gas, which is pretty good.
I have reason to believe that the fuel pressure regulator may be going bad as well, which can cause bad milage or the car to run rich; there seems to be quite a bit of black 'carbon' soot on the tailpipe. Or this could be from a faulty 02 sensor.
I will be changing out the thermostat tonight, the oil, and the tranny fluid as well.
Thanks for any input.
EDIT: I just thougth of something, could a bad PCV valve make the car get bad gas milage as well? The honda one costs $22 from the dealer, and I am having trouble finding it at parts stores.