Some diagnostic assistance please (Fix Or Repair Daily )

So the elderly Ranger is still giving me issue. I had thought it was the MAF as the problem (complete and abrupt power cut) went away when I unplugged the blessed thing.

So a couple weeks back I sprang for a new MAF from Autozone. It seemed to work......for exactly 10 miles. So that one got returned and I bought a Ford unit from the Ford Dealership.

This one didn't appear to work directly out of the box. Now before I enlessly replace this thing is there something else I should look at that is also "taken out of the loop" when the MAF is unplugged?

vital stats: 1994 Ranger 4.0 5 speed 80,000 miles. New plugs, plug wires, battery, fuel filter, charge air temp sensor, MAF. Tried the "count the blinks" trick and it came up with litterally two dozen different codes (some related to the automatic transmission ??!?) and since it's OBD1 I got the "mechanic" at work to put a scan tool on the thing, according to the scanner it had no codes happening.

So what else should I replace? TPS? MAF pigtail? Some as yet unknown third party I haven't thought of? I'm much happier fixing brakes than dicking with some electrical gremlins, this is outside my skill set.

Try unplugging O2 sensor.

Sorry, forgot to include. New O2 sensors as well.

What would unplugging them accomplish?

So uh...whats it doing? Edit: i see you said complete power cut, please divulge a bit deeper, when and how? Is it loss of power, motor dies, misfire, ect

You seem sure it was a maf and by unplugging it and it running better sounds like it, but weird the two you bought didnt work. Got any junkyards around to grab one or two for cheap? Or even better find someone with a similar truck and swap mafs

More detail: well, the truck will free rev perfectly, no problems at all. But when you put a load on it it will start to pull and then cut out BANG, hard cut of power, enough to chirp the tires and slam the motor over on it's mounts. The engine dosn't die, just goes to idle. You can bring it back by feathering the throttle, but it's so unpleasant and frequent the truck is effectively undrivable in that mode.

KyAllroad wrote: Sorry, forgot to include. New O2 sensors as well. What would unplugging them accomplish?

They're likely taken out of the loop when you yank the MAF plug.

Have you checked fuel pressure? Sometimes they'll run deceptively ok on E36 M3 fuel pressure. Also, did you reset the computer (unhook battery, turn on headlight switch, walk away for a while)? The trims can get screwed up enough that they'll run like crap for a while with all the parts in good working order if you don't start from the defaults, at least with OBD2.

We need to talk about your tps reports.

Did you get the memo?

Seriously though, sounds a lot like a 90's ford tps gone bad.

TPS was high on my list, I'll do it next. Thanks.

Does it have one of those camshaft position sensors that look like it was made out of half a distributor? I've seen them cause some weird driveability issues.

What codes did you get?

On a car of that era, I would suggest doing a KOEO and a KOER test. Those will cycle through the systems to see if it can find something obviously wrong. It's been a LONG time since I ran one, but I don't think it was hard.

See what those tell you.

In reply to alfadriver:

I did those and got a LOT of codes (the aforementioned 2 dozen). If it weren't for the fact that it was my late fathers' truck I'd sell it and drive almost anything else on days I don't take the Miata.

But it was and I'm keeping it as an around town scooter for the foreseeable future. OBD1 just sucks.

Replaced the TPS. No luck there.

It appears I've found the culprit. Plug for the MAF.

Replaced it this weekend and no problems since. Here's hoping!

KyAllroad wrote: It appears I've found the culprit. Plug for the MAF. Replaced it this weekend and no problems since. Here's hoping!

That could do it. Bad connection from a sensor that throws the voltage the ECU is reading off a bit can cause some weird E36 M3 to happen. I had an intermittent sticking high idle in the Jeep for a while that I couldn't figure out. Seemed like I was just killing a TPS every few months. Until I noticed that wiggling the TPS connector wires would fix it. New connector and boom, problem solved.

KyAllroad wrote: It appears I've found the culprit. Plug for the MAF. Replaced it this weekend and no problems since. Here's hoping!

Early Ford Focus was famous for this. Half the MAF problems could be traced to a broken wire just where it went into the connector.