Got a stumper for the crowd

[thekubiaks]

My 97' Explorer is running perfectly but is getting about 15-16mpg in the city. I did all of the usual fuel mileage improvement stuff. I hooked a code scanner up to the car that can read sensors as I drive. I have no codes and all sensors were good except the vehicle speed was listed as ZERO and the Fuel System stayed in Closed loop the entire 20 mile trip, even under hard acceleration. The motor still ran perfectly and the coolant temp stayed at 190F, +/- 5F. Anybody know what I can do?? Should I replace the Vehicle Speed Sensor?? The speedometer is fine... THANKS

 

[BradE.]

Uhhh, 15-16 MPG is pretty normal for a X in city driving. Does not sound like anything is wrong to me.

Your code scanner might have trouble reading Ford sensor values, many do. If the speedo is working fine I would not worry about it.

 

[thekubiaks]

thanks for the reply, I suspect you are right about the scantool not being able to read some sensors....AK

 

[Alec]

Sounds like you have a great running rig.

 

[X24]

What engine is in it?

 

[Jason_25]

I noticed that my Scantool always thinks my engine is in closed loop mode, even on start up. Don't worry about it.

 

[coolchris]

i wish i could get 15-16 mpg.... im more in the 9-10mpg range

 

[Majisto]

These aren't Civics you know? (Thanks God!)

 

[Robert]

Your engine should switch to closed loop as soon as your PCM is getting readings from all of your sensors that fall within their normal ranges. Depending on how warm your engine is when you start it, it can be anywhere from a couple of seconds to several minutes. You want your engine running in closed loop. That is the mode where your PCM is making all of the adjustments to your engine parameters to make it run at it's most efficient level. In open loop mode, your PCM sets some parameters to default settings which will lower your gas mileage, increase your emissions however it will help your engine warm up quicker. As far as the 0 speed on your vehicle speed, that is normal for '97 & '98 Explorers and aftermarket OBD-II scanners. Ford didn't follow the conventional OBD-II protocol on many parameters until '99 so many things won't display at all on aftermarket scanners, other things can only be accessed through the Ford enhanced OBD-II mode.