My engine has gremlins (read below)

[tommo77]

So I got a ranger on the cheap but the motor is 'funny' idles 'ok' runs ok some times, then some times it's rough as guts. Attached is the stored codes.
Changed the maf, plugs, wires, and coil.
Maf reads 0 signal on my blue drive scanner.
And some times randomly the CEL blinks slowly for a few min then goes back to solid on.
My question is, can it be a timing issue? ( I guess the timing chain was done over the winter before I got it.
Could it be a fuel or vacuum problem?
Any help is greatly appreciated.
Thank you in advance.

 

[tommo77]

This is the lower half of the scan

 

[rusty ol ranger]

This is the lower half of the scan

What year and how many miles? SOHC or OHV?

 

[tommo77]

What year and how many miles? SOHC or OHV?

2004 230k not sure if it's ohc or ohv. It's belting down with rain at the moment once it stops I'll go have a look.

 

[rusty ol ranger]

2004 230k not sure if it's ohc or ohv. It's belting down with rain at the moment once it stops I'll go have a look.

Eh all 4.0's were SOHC by 04.

Im not sure if a timing chain issue would cause that. With that many codes it seems maybe its a wiring or ecm issue. Someone who knows them more will be along to help more

 

[Broosedamoose]

Doesn't sound like a timing chain issue. It would be consistent and either run crappy or run decent. Seems like an A/F problem.

 

[tommo77]

Doesn't sound like a timing chain issue. It would be consistent and either run crappy or run decent. Seems like an A/F problem.

Yea, if anyone knows what voltages I should get on the maf that would be helpful, I can't find a schematic for it but I'm getting 14v on red and 5v on the light blue on the opposite side.

 

[superj]

i guess its a heated wire maf? not a swinging barn door style?

google brings nothing on what readings you need?

 

[tommo77]

I think it's a wire type, Google is less than clear. I'll keep looking I just figured someone might know what reading I should be getting to determine if the ECU is junk or there's a wire issue

 

[rubydist]

The mafs issue is the primary one - you need to fix that first. It could be a bad wire in the harness, a bad connection, a bad mafs, or a bad pcm. Once you get that sorted out, the other issues may go away, else you can tackle them one by one.

 

[tommo77]

The mafs issue is the primary one - you need to fix that first. It could be a bad wire in the harness, a bad connection, a bad mafs, or a bad pcm. Once you get that sorted out, the other issues may go away, else you can tackle them one by one.

That's what I'm thinking I just need to figure out what wires go where and what signals I should be getting

 

[rusty ol ranger]

5v should be the reference signal...14 coming out is probably the actual reading signal. And seems oddly high but im far from expert

 

[tommo77]

5v should be the reference signal...14 coming out is probably the actual reading signal. And seems oddly high but im far from expert

That's a picture of the wires im guessing red is normal battery / alternator voltage and the light blue opposite is the 5v. Then there are 3 others excluding ground that have no signal. My next guess is to unplug the ECU connection and tone out each line for continuity but that's a stab in the dark

 

[tommo77]

Ok so attached is the diagrams I believe are for this truck.

I have continuity for the maf return signal to the PCM (light blue/tan)

So I'm leaning to the PCM being faulty?

 

[tommo77]

Ok so since it's not raining I've done some probing.
All wires to and from the PCM are fine. I unplugged the maf and truck runs fine no misfire codes, just the code for the maf being unplugged.
I'm really starting to think the PCM is junk.