1999 Ford Ranger

No matter how long i let the truck warm up or how long ive been driving it, when i hook up my scanner it says

Fuel Sys 1: CL
Fuel Sys 2: O

I'm assuming CL is closed loop and O is open loop.

Why does the second bank never go into closed loop? What should i check? My last tank i averaged roughly 19 mpg on about 80/20 city/highway driving and shifting at 2k rpm with a few bouts of WOT 5500 rpm shifting.

Also, which banks are which? Is bank 2 the driver or passenger side?

 

On the 6 cylinder, bank one refers to the side that has cylinder 1.

No trouble codes set?

 

no trouble codes. and yes, all oxygen sensors seem responsive to changes in throttle position throughout their whole preset band.

As for the other part, let me ask you again. Which side has cylinder 1?

 

Google is your friend (paste "1999 Ford ranger firing order" in the search bar). You get:

 

thanks. i noticed my bank 2 (which wont go into closed loop) o2 sensor 1 never has it's voltage go above 0.18 or so. It still changes (I watch the numbers change in the PID menu on my scanner). However, it never goes above 0.18 and I believe that's causing the bank 2 to dump lots of fuel and possibly not go into closed loop?

 

Would cleaning the electrical connection on the oxygen sensor be a good place to start?

 

Can't hurt. Also check (with an ohm meter) the connections from that O2 to the connector to the ECU.

How old is that O2 sensor?

 

not sure on how old.

but get this. today i was looking through the PID data and the bank 2 sensor was functioning through its full range of voltage (0-1V), but the fuel trim from that o2 sensor still read 99%. IDK why that is.