91 Ranger XLT 3.0L v6 EFI Code 22 BUT Ford says NO MAP sensor

So far nobody has an explanation for this one.

The "check engine" light on my 91 Ranger came on some time back. The truck did not run any different after the light came on than it did before the light.

The self-test just gives Code 22 on KOEO (both O & C codes). Every reference that I have found says this is "MAP/BP sensor out of range". But Ford says the 1991 Ranger XLT 3.0L v6 does NOT even HAVE a MAP sensor.

Yes, I know that it has an MAF sensor instead thought nobody has been able to explain how a Mass AIR FLOW system can replace a Manifold absolute PRESSURE (ie vacuum) based system.

So what is causing the computer to read the code 22? And what can be done to correct the problem & turn the "check engine" light off again.

And, BTW, yes I have reset the soft code storage. And know that the reset worked because immediately after having done the reset the KOEO test gave 22 22 1 11 indicating that the C (soft code) storage had been cleared.

On the same topic, can anyone tell me for certain where the microprocessor unit that generates the self-test codes is located on the truck? I have 3 different answers so far but none appear correct.

While we're at it, how exactly does an MCU differ from a PCM or an EEC or an ECU. Are they all the same unit or different physical modules?

TIA!

Bob W Miami FL

Reply to
raweeks
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That's correct.

They replace a MAP system because the MAF sensor can very accurately measure the mass of the air that is flowing into the engine. MAP systems are rather crude in comparison to a MAF system, though either one can get the job done in many instances.

Repair the problem with the barometric pressure sensor.

Your truck -does- have a MAF sensor. Your truck -does not- have a MAP sensor Your truck -does- have a BP sensor.

Have you looked behind the right side kick panel?

BTW, the BP sensor is supposed to be mounted to the firewall adjacent to the heater/evaporator housing.

MCU, PCM and ECU are all acronyms for the engine control computer, some are significant to the type of system they were used to identify (EEC-III vs. EEC-IV vs. EEC-V). EEC itself simply means Electronic Engine Control, a generic term much like saying dessert versus cake. Back when it all started in the early 80s, GM favored ECM, Ford Favored ECU and EEC processor, Chrysler used logic module/power module and then went with SMEC, SBEC, JTEC etc. PCM is now the SAE defined acronym for the engine control computer.

Reply to
aarcuda69062

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