Hello all,

I have a 2002 ranger edge 3.0 4x4 manual (not flex fuel) w/ 130k miles

I'v been lurking on this forum for awhile and haven't found an answer to my CEL codes P0172, P0175 indicating both banks are running rich and codes P1132, P1152 indicating lack of both upstream O2 sensors.

My question is how do I resolve these codes? I have replaced TPS, thermostat, pcv valve, both upstream O2 sensors, fuel filter, spark plugs and wires, cleaned MAF and IAC, checked for vac leaks, and checked for a blocked purge valve solenoid. I also back probed MAF and ECT sensors to verified they are getting voltage and working and disconnected the IAC to see if that functioned properly. I've been using 87octane fuel.

The truck will idle erratically and stall at idle but only after driving for around 10 minutes and coming to a compete stop at a stop sign or in traffic. I noticed I can sometimes fix this problem in a moment by shutting off my ac or heat. Also this issue only happens if I try to reset the ecm/pcm by unplugging the battery for 30min. After a few days of driving all stalling issues at idle go away. So any ideas as to whats going on? My only next step is to go to a dealer and reflash/update the ecm/pcm and if that doesn't work I don't know what will.

 

Welcome to the forum, well first post in any case, lol

Is the engine factory or was another 3.0l swapped in?

Rich codes are unusual UNLESS someone swapped in another 3.0l that had larger fuel injectors, like Flex Fuel engines did(or they thought they would get more power, lol)
If so you will get Rich codes

Is the engine actually running Rich?
Pull out a few spark plugs and look at the tips, light brown means good burns, dark color means Rich burn, blackish means oil burns

Its possible to have a leaking injector, but on BOTH banks of the engine would be very longs odds on that scenerio
But if a spark plug shows darker tip where others show lighter then that is possible

Rich codes mean the computer calculated air/fuel mix was "heavy" with fuel, so computer is having to close injectors sooner than planed to get O2 sensor voltage down
O2 sensors see Oxygen not fuel
Low oxygen sets .9volt, rich burn
High oxygen sets .1volt, lean burn

Computer tries to get .4v back from O2 sensors, by setting correct Open time for each injector
Computer doesn't have a fuel pressure sensor, it "expects" 55psi, if pressure was say 70psi then too much fuel would flow out when an injector opened, so Rich, long shot on this one, but if Fuel Pressure Regulator(FPR) in the gas tank failed it is possible for pump to generate 70+PSI

Computer is also programmed for injector size, it "knows" how much fuel will flow out if injector is opened for say 100milliseconds, if larger injectors are installed then more fuel flows out than expected so Rich mix

Clogged exhaust should set Lean codes, and you would have running issues at highway speeds

Could be intake air restriction, check the cold air intake tube and air pre-heater valve in it, and of course air filter

Ultimately it could be a bad computer, which is hard to diagnose since there is no "test" for PCMs, it's one of those, "tried everything else" so must be computer issue

2002 PCM will have PATS so not an easy swap, have to add your keys back once new PCM is installed
New PCM will come with 2 new keys, which can be cut to match your current keys

 

Thank you RonD for answering my question. I will look at some of the things that you said and see if I have a few more rabbit holes to go down.

 

@RonD do you know what the resistance of the fuel injectors should be on 3.0 v6 ranger from 02. I tested them and they are 11.8 does that sound right to you?

 

Yes, 11-18 ohms is spec

 

Do you happen to know how to identify the regular vs flex fuel injectors? The part websites just lump them together so it's basically impossible to figure out unless you know the part number.