Engine trouble code 171

[wgb]

I have a 2wd '95 Ranger with the 4L v6 and 5 speed trans. It starts and runs fine, but it has a 171 engine code (lean on bank 1). What are some common causes for this code? I am a shade tree mechanic and can usually fix problems with my cars. But I need some help knowing where to look for this problem. No drivability problems, just don't want to burn a hole in a piston and have a real problem. All suggestions will be appreciated and followed up.

 

[SenorNoob]

Has that O2 ever been replaced that you know of? They do have a lifespan. I think as they wear the they read leaner. What do the plugs look like on that side? It does have 2 O2 sensors right?

I'd expect a anything else (except a single clogged injector) to set a code for each side. Low fuel pressure or vacuum leak, etc.

 

[wgb]

Thanks SenorNoob. It has three sensors; one for each head and one after the CAT.
I've looked into ways to test them. I am wondering if I exchanged the ones on the headers (right to left, etc), cleared the code, and ran the truck, if it would give me a new code for bank 2? That would give me a pretty good indication that the one then on bank 2 is bad. What do you think?

 

[SenorNoob]

Only problems I can see with that is will the wiring reach/plug in and are they stuck?

 

[rumblecloud]

As Senor mentioned, O2 sensor removal can be a real pain. .Switching should give an indication of sensor fault. However,I realize there is a cost involved, but once they're out, you would be better off replacing them - especially if there's high mileage involved.
There are a couple of vids on the tube for code 171 (too much air and not enough fuel ) - if you haven't already checked.

I've farted around on my 94 for months now and still can't find the issue - vacuum leaks, multiple MAFs, etc - even replaced wiring from the PCM to the MAF...still can't find the issue. Good luck with it and please do let us know what you find.

 

[alwaysFlOoReD]

Thanks SenorNoob. It has three sensors; one for each head and one after the CAT.
I've looked into ways to test them. I am wondering if I exchanged the ones on the headers (right to left, etc), cleared the code, and ran the truck, if it would give me a new code for bank 2? That would give me a pretty good indication that the one then on bank 2 is bad. What do you think?

Swapping the sensors, but not the wires, makes sense. Same as swapping a sparkplug to see if the issue follows the plug.

 

[Kira]

How many miles on your '95? Is it a daily driver or not?
If the truck just does local driving, does the tank with Techron or Red Line fuel system cleaner.
The stuff works upon shutdown to remove schmutz from the injector nozzles. Hey, you never know!

Sometimes a load of Top Tier mid or premium fuel and a highway run can help a lot.