How to do it.
I had prepared a long, detailed post once I had solved this problem but, since there didn't appear to be a lot of interest, never did send it.
The local Ford dealers all told me that the 1991 Ranger HAS NO MAP/Baro sensor. NOT TRUE!
The answer is that Ford plays games with the parts terms. And went out of the way to make this part hard to locate on the 1991 Ranger.
Open the hood and look on the upper firewall just a little to the passenger side of the middle.
The sensor is IDENTICAL to the previous years' MAP/BP but is about 3/4 hidden in a recess in the firewall. All that can be easily seen is the electrical connector and the nipple (to the driver's side of the connector) where the vacuum hoze WAS connected in earlier years.
No vacuun hoze connected - can't be a MAP/BP sensor, can it? Yeah; riiiight. BTW, mine has a white piece slid over the vacuum hoze nipple that changes the appearance enough to make things even more confusing.
The sensor unit is loose inside a "pocket" made by a plastic "cup" held in the firewall by a plastic cover over the front of the sensor, with cutouts for the electrical connector & the nipple. This retaining piece can be removed by using a flat head screw driver to pop loose the "clips" that secure it to the firewall.
And, YES, I DID buy a MAP/BP sensor for a 1991 Ford Ranger from Advance Auto here, identical to the old one, & replaced my old one with it. Reset the self diagnostic systems and have had no "code 22" problem since.
And all the other problems mentioned cleared up after to system "relearned" the truck's operation patterns.
BTW - The MAF (Mass Air Flow) sensor does NOT replace the MAP (Manifold Absolute Pressure) sensor (by what EVER initials you wish to call it) in the 1991 Ranger. MINE has them BOTH. The first on the air intake & the second in the firewall.
Bob W
Miami FL
