completely guttless AND terrible mpg

[RonD]

O2 has the biggest "say" in the air:fuel department, as far as sensors, computers interpretation of the sensor data is of course the ultimate control.

MAP sensor allows computer to set baseline 14:1 air:fuel
After cylinders burn this mix, O2 sensors report lean/rich oxygen levels
Computer adjusts mix ratio, fine tunes, for best MPG
Computer changes mix slightly a few times a second to hover around the O2 sensors "sweet spot", .4-.5volts
This switching allows computer to test if O2 sensor is responding fast to changing mixes and also responding correctly to lean or rich.

Computer has pre-set parameters for engine size and injectors dwell time, if injectors are being opened to long to achieve .4v O2 response then computer will set a Lean code, engine isn't running lean the code is set because there is a problem with the system, could be a vacuum leak, more air than calculated or low fuel pressure, so longer injector open time needed.

 

[nesralyrrej]

That much I understand, but when I unplug the O2 sensor won't the computer just disregard the rest of the sensors and run how it wants to?

 

[nesralyrrej]

okay so, I unplugged the oxygen sensor and the cel doesn't illuminate, and furthermore it runs seemingly exactly the same. so does that mean that my computer is bad?

I tried to run the codes, via the flashing cel and it just stays off until I turn the key off and back on then its just solid on. any idea what I should do??

 

[RonD]

Yes, starting to look like a computer issue, might be worthwhile pulling the top of the computer and look at the circuit board.

Good look at EEC-IV here: http://www.auto-diagnostics.info/ford_eec_iv

Did you add the jumper wire so CEL would flash the codes?
Good read here on retrieving OBD I codes

 

[nesralyrrej]

Yeah I out the jumper wire in and it didn't flash any codes at all

 

[RonD]

Computer should at least flash "OK" code.

So computer may be the problem.

OBD I testing methods are here: http://www.therangerstation.com/tech_library/OBD_I.shtml

If you want to try to test computer response with test light or meter

 

[nesralyrrej]

So once upon a time I read that you can use a v8 ecu for a v6 as long as it's the same metering and stuff, but not a v6 ecu in a v8 because it would be missing information Like injectors and what not, is that true? I have two 5.0 Ecuador I can try right now if so

 

[RonD]

I would say no, different firing order for injectors would be primary reason, even if batch fired.
1-4-2-5-3-6
1-3-7-2-6-5-4-8

And because of your specific issues you really wouldn't accomplish anything, IMO

 

[nesralyrrej]

True, so this time I ran the codes again and actually got a flash, It flashed 6-7. 6-7 then stopped so code 67, neutral position switch? It's a manual

 

[RonD]

Manuals have the Clutch Pedal switch, and some did have neutral switch on the upper trans shift housing, but not Rangers.

It could just be a broken wire on the clutch switch, or switch itself.
Does the clutch pedal have to be pushed down to the floor to get starter motor to turn, if not then clutch switch is broken or by-passed.

I can't see 67 causing your issues through?
Pin 30 on the PCM is the "neutral" detection circuit

The fact you did get a code means computer is at least "talking", even if it doesn't make alot of sense, after clearing codes and retesting can you get the 11 code, System checks OK

 

[nesralyrrej]

Clutch needs to be pressed all the way down, I'll reset it again and check. I still may pull one out of a salvage yard truck and see if it helps any