I am interested in buying a 2002 Ford Ranger 2.3L 4Cyl with a manual transmission and 171k miles and with the codes P0171, P0113, and P1506. When I drove it, it was idling high and there was a lot of bucking when I would accelerate. However, if I pressed the gas pedal down enough, the bucking would stop, though it did not have as much power as it should. I do not have much experience with working on cars, but I am trying to learn. From what I looked up online, it seemed like these could be possibly fixed by cleaning/replacing some filters, or replacing a part to fix a leak.

I would really appreciate if anyone could help me gain an understanding of what could be wrong, and how difficult of a fix it could potentially be. I was thinking of buying it for $2,000, but maybe the problem is potentially worse and I can talk him down? I can go see it again, so if you have suggestions on what else to look for that would be great too. Thank you.

 

Welcome to the forum

You should post the code definitions with the codes since you have already looked them up I assume
And you NEVER EVER Google a code number, look it up on a FULL LIST of all code numbers, like this one: OBD-II Trouble Codes : The Ranger Station

P0171 System too Lean (Bank 1)..........4cyl engine only has 1 Bank, V6 and V8 engines have Bank 1 and Bank 2
Lean code doesn't mean engine is running Lean, it means the Computer is having to add more fuel(open injectors longer) than it calculated to balance Oxygen levels at upstream O2 sensor(O2 closest to the engine)

P0113 Intake Air Temperature Circuit High Input..........if you look at the full list you will see computer could have picked another code if wiring was a problem(P0109), or if sensor was erratic(P0111/P0114)
This could cause the Lean code and running issues
Air temp sensor is part of the MAF sensor, there are 6 wires connected to MAF sensor, the 2 outside wires are for the IAT(intake air temp) sensor, check all the wires as far back as possible, get replacement MAF from wrecking yard for testing

P1506 Idle Air Control Overspeed Error..........this means the IAC(idle air control) Valve has closed all the way and engine RPMs are still too high at idle, most likely a vacuum leak
Vacuum leak will cause Lean code as well, so I think P0171 is a symptom of the problem


I don't see a Major issue unless this is a Computer issue and there is no way to tell that until you start testing things, but computer issue would be way, way..........way down on the list of possible reasons for these codes

 

Thanks very much for taking the time to reply! I'll keep that link handy so I can always refer to all the codes, that makes a lot of sense.

 

Quick question. If I unhooked the idle control valve, that will leave the valve closed? I unplugged it and the engine kept running with no change, this is most likely because of a vacuum leak then? Also, there is no jerkeyness if I just reviewed it in nuetral, is that normal under the assumed conditions?

 

Yes, you have a vacuum leak most likely if idle didn't drop, but................

You can take off the IAC Valve, 2 bolts, plug its wires in and turn on the key, engine off
IAC Valve should be open with key on engine off, now unplug the 2 wire connector and valve should close, plug it back in and valve should open again, repeat as you see fit.

If valve isn't moving then test the 2 wires, one is 12volt other other ground with key on engine off
If you have power then replace IAC Valve

 

Thank you. I did that, and found that my IAC is not working, so I will replace that. I also noticed something else today, when I revved the engine, some blackish smoke would come out of the exhaust. Can this be explained by the failed IAT sensor or a vacuum leak, or is this something else?