upnsmoke
New Member
Well, it's raining again, so I'll go ahead and write up this post. I'm working on a 99 Ex manual trans with 80k miles. The car has no drivability issues, idles smoothly at normal speeds, and pulls strongly as it should. The problem is that the fuel mileage is currently 24 mpg in the city, and has been as low as 19. It is running rich enough to get the oil smelling like gasoline. I am changing the oil frequently in hopes of not killing the bearings.
The list of what I have checked and done so far:
new O2 sensor- changed mileage from 19 mpg to 24, not a huge change in performance, though it does feel a little sharper
checked throttle position sensor, intake air temperature sensor, map sensor- all in spec
did plug wires, cap and rotor, regapped plugs to .040-no significant change
tires are inflated correctly
Fuel pressure is in spec and does not leak down significantly with engine off, as tested several times, even overnight once. I believe this rules out a leaking injector, or a leak in any line between tank and fuel rail. I could be wrong about this. If anyone knows any other check relating to this, please chime in. Otherwise, fuel pressure seems to respond normally to changes in engine load and unplugging and restoring vacuum to the fuel pressure regulator, which I believe indicates correct function of the regulator.
Still unknown:
Is there an exhaust leak upstream of the first O2- I hope to answer this today
Is the ignition timing correct- I willcheck this today
Is there a leak in the fuel tank- I doubt it, but I intend to find out for sure
Would resetting the ECU be necessary/affect performance? If so, what is the best way to do so?
Any thoughts on this are appreciated. Would a leak in the fuel tank cause a CEL? Evap emissions or something? Is there an easy way to do a pressure test on the tank? Can anyone think of any other cause for rich running? Thanks in advance for any help you guys can give.
The list of what I have checked and done so far:
new O2 sensor- changed mileage from 19 mpg to 24, not a huge change in performance, though it does feel a little sharper
checked throttle position sensor, intake air temperature sensor, map sensor- all in spec
did plug wires, cap and rotor, regapped plugs to .040-no significant change
tires are inflated correctly
Fuel pressure is in spec and does not leak down significantly with engine off, as tested several times, even overnight once. I believe this rules out a leaking injector, or a leak in any line between tank and fuel rail. I could be wrong about this. If anyone knows any other check relating to this, please chime in. Otherwise, fuel pressure seems to respond normally to changes in engine load and unplugging and restoring vacuum to the fuel pressure regulator, which I believe indicates correct function of the regulator.
Still unknown:
Is there an exhaust leak upstream of the first O2- I hope to answer this today
Is the ignition timing correct- I willcheck this today
Is there a leak in the fuel tank- I doubt it, but I intend to find out for sure
Would resetting the ECU be necessary/affect performance? If so, what is the best way to do so?
Any thoughts on this are appreciated. Would a leak in the fuel tank cause a CEL? Evap emissions or something? Is there an easy way to do a pressure test on the tank? Can anyone think of any other cause for rich running? Thanks in advance for any help you guys can give.