poor gas mileage - Ford Forums

11-22-2003, 12:33

I have a 1996 2wd 4.9 (6cyl) std cab with a manual transmision. My highway mileage is 11mpg. Had things tuned and checked but this didn't help. Current miles are 67M. Is there anything that can be done to get better mileage.

89F150 · 11-22-2003, 19:13

That is pretty bad, have you changed things like oxygen sensors. Thats the only thing i can think of at the moment

11-23-2003, 06:39

No. The oxegen sensor has not been change, it was checked during the tune up. Not sure how they check something like that though. Might be worth just changing to see if it helps.

89F150 · 11-23-2003, 18:13

You might have a couple of 02 sensors, something about OBD11 or something. Sorry about not knowing much :s6:

351w · 11-23-2003, 18:23

i think if the O2 sensor was bad it would run very rich and have very little power as well.
the other things to check is to see what shape the engine is in by doing a leakdown test or compression test on it.
then also check to see how much back pressure your exhaust has, possible a blocked muffler or cat converter.

89F150 · 11-24-2003, 04:34

Is it true O2 sensots are supposed to be changed around 50000 miles? If it is, mines due a while ago

351w · 11-24-2003, 20:59

as a preventitive maintenance they can be changed but i dont know of any written statement that says they need to be changed.

'92BigBronco · 11-25-2003, 00:29

Anytime you notice an increase in gas consumption, the O2 sensor is usually the culprit if the engine is in good tune and the fuel pressure regulator is working ok. An O2 malfunction will cause the engine to run rich, but won't richen the mixture enough to cause a noticable loss of performance in most cases.

The O2 sensor only sends data to the ECU when the engine reaches normal operating temps. Until then, the sensor runs in open-loop. If the sensor goes bad, the engine runs in open-loop all the time and generates a check engine light. However, an old sensor can cause a loss of economy and not generate a trouble code.

89F150 · 11-25-2003, 17:12

I may have to check out one of them too see if i can improve my milaeage.