94 Ford Ranger MAF, IAC?

NETAW

MEMBER
1994 FORD RANGER
4 CYL
2WD
MANUAL
72,000 MILES

I bought a 94 ford ranger 2.3L from an auction, Ran great of course til I got it home. Started to loose power when I pushed the accelerator it acted as if I hadn't pushed on it at all. I got some codes from a reader, 157, 159, 116, with key off, with key on 412,538,521. After using a Ford Site for help, I started trying to figure out what was wrong. I started by replacing wires and spark plugs. I cleaned the MAF and IAC with cleaner. Those didn't work. Oddly when I unplug the MAF, the truck seems to run find outside of the Service Engine Light being on. Plug it back in, and the truck with either die or idle badly for a few minutes and die. I bought a new MAF and IAC, put them both in and it's changed absolutely nothing.
I'm sort of at a loss now, what to do, any ideas. I'll be running out of money soon.
Thanks for your feedback.

4 Replies

ERNEST CLARK

MECHANIC
1,730 POSTS

First, let me advise you not to chase down problems by replacing parts. That is expensive and never works. Always test parts before replacing them.

Now for your issue, it's almost impossible for all of these sensors to fail at the same time. So your problem is in the wiring harness, the computer or bad grounds in the electrical system.

Your grounds are easiest to check, so start there. Check all cables for breaks/high resistance. Check all connections at frame, engine and body for looseness/corrosion.

If they all check out, move to wiring harness. You'll need to get a diagram that shows colors/connector views. Trace the wires/connectors with a volt/ohm meter looking for breaks and high resistance. (Don't forget a visual inspection for broken/bent pins in connectors and for burnt wires in harness)

If harness checks out, check computer by first making sure it's grounds are good as well as the connectors are all tight. If they're good, your computer is bad.