Rearanger
Active Member
- Joined
- Feb 4, 2008
- Messages
- 1,429
- Reaction score
- 23
- Points
- 38
- Location
- Southeast USA
- Vehicle Year
- 2003
- Make / Model
- Ford
- Transmission
- Manual
I have been monitoring my average fuel consumption since I purchased this truck - there are a lot of data points. The mileage peaked at about 23K and held steady until about 36K when it started a slow decline. My driving habits are fairly constant and the ethanol content has always been about 10%.
At about 11K I did a hot engine compression test and got numbers from 185 to 195. I just did another at 69K and got the same numbers - so lost compression is not the cause. The plug condition showed perfect fuel burning.
It appears that it's time to try replacing the O2 sensors to get my mileage back. This truck has one on each bank and a third downstream of the CAT. The downstream sensor is called a CAT efficiency monitor.
My question is, does the after the CAT sensor contribute to fuel trim? My FSM did not indicate this and searches here were fruitless. There was some Goggle discussion both ways - but not about the Ranger.
Any techs out there that can tell me if it's worth replacing the downstream for better mileage?
Thanks
At about 11K I did a hot engine compression test and got numbers from 185 to 195. I just did another at 69K and got the same numbers - so lost compression is not the cause. The plug condition showed perfect fuel burning.
It appears that it's time to try replacing the O2 sensors to get my mileage back. This truck has one on each bank and a third downstream of the CAT. The downstream sensor is called a CAT efficiency monitor.
My question is, does the after the CAT sensor contribute to fuel trim? My FSM did not indicate this and searches here were fruitless. There was some Goggle discussion both ways - but not about the Ranger.
Any techs out there that can tell me if it's worth replacing the downstream for better mileage?
Thanks