Solving engine trouble codes 22/23 OBD-1

[howdisrespectful]

Hello all I’m a newbie and am looking for some advice/tips/. I am the new owner of a 1991 4.0 ohv XLT 4wd Ranger and I’ve got some trouble codes.

the engine has a rough idle and will get very jerky when passing 3k rpms in any gear.

Code 23 is for the throttle position sensor and after some research this is what I’ve found:
there is an aftermarket TPS on (Standard Motor Products) and its voltage reads .36v at idle and 2.2v at wide open throttle. I understand that this is well below spec. I also happen to have the original Ford TPS so I plugged it in and it read .24v at idle and 1.89v at WOT.
I am planning on buying a motor craft TPS and replacing it however I was wondering if there was another reason which would cause low voltage that I am missing.

Code 22 is for the MAP/BARO sensor and this is what is really confusing me. After searching the forums I learned that some rangers of my era don’t come equipped with either and instead have a MAF sensor only. I examined the location where the MAP/BARO would be and there is only a loose connector and a plastic cover over where the sensor would be. It is very professional and looks to be from the factory.
could my MAF sensor be giving me the code 22? I have tried cleaning the MAF with iso alcohol and a q tip but there was no change in performance.


also I recently replaced the cylinder heads and fuel injectors but the problems were present before any work was done, and they have not changed whatsoever after work was completed. and I replaced ALL battery connection terminals positive and negative as well as installed a new battery and the issues are identical before and after work was completed. Any advice AT ALL would be appreciated!! Thanks!!

 

[SenorNoob]

On a 91, how are you reading the codes? It's easy to miss a cel flash if that's what you're doing. Otherwise, has someone swapped parts? Also, can you check power incoming (VREF) to the TPS?

TPS Testing

If the VREF is not at ~5v nothing else will be right.

 

[howdisrespectful]

I am reading the codes with the old paperclip method
I have done it over five times now so I am positive I am not missing a flash.

I tested the voltages of all sensor connectors and the voltages are as follows:
TPS 5.0v
MAF 11.98v
BMAP 5.0v

I also went through the entire intake system so check for holes or gaps or things not sealing but all seemed to check out. I didn't notice anything out of the ordinary.

Previous owner swapped the EEC out and new one has the number F17F-12A650-FA X1L
I cross referenced the number with fuelinjectedfords.com and the serial code checks out for a 4.0 but the X1L is nowhere on the page. Could I have an incorrect EEC?

I ordered a motorcraft TPS and will be swapping that in hopes of solving the code 23

 

[SenorNoob]

Being a different engine computer, might try grabbing a junkyard map and plugging it in. I have one plugged in on my swap. It's from the original 2.9. Whether it does anything or not, IDK.

 

[RonD]

During the conversion from MAP speed density system to MAF system Ford left the a BMAP sensor in MAP sensor location, which was just for local air pressure, i.e. sea level, or 5,000ft elevation(Denver) which matters to air/fuel mix

The MAP and BMAP are the same sensor, with key on the MAP sensor would tell computer local air pressure prior to engine startup
But after startup MAP was used to measure engine load, by measuring Vacuum in the Intake Manifold, and could no longer measure local air pressure, which DID cause issues in mountain driving when there were big changes in elevation, more than a few people using this system would comment that the engine started to run better after they stopped for gas, thats because of the key off and then key on which reset the local air pressure used for fuel calculations

The BMAP had the same 3 wire connection but vacuum hose port was left empty, it was just there to sample local air pressure, so the B was added for barometric pressure

After a few years it was found the MAF did just fine without BMAP in adjusting to mountain driving
With MAF data, RPMs, air temp and Throttle position the computer could calculate approx. "barometric pressure" and engine load of course

 

[howdisrespectful]

UPDATE:

I recently replaced my TPS with a Motorcraft sensor and it definitely did what is was supposed to do!
The idle smoothed out by a ton and it ran much better than ever before!
Before installing it I unplugged my battery and allowed my computer to reset so there would be no issue.
I took it out for a 10 mile drive or so and everything was great!!

Yesterday however, I took it out for another ten mile drive and stopped to hit a drive thru. The line was rather long and I was idling for ten minutes or so. Towards the end my idle began to get rough just as it was before and I felt a loss of power.
I headed home and on the way i felt small jerks while driving (kind of like a hesitation, almost as if the truck was being tugged slightly every few seconds or so).
I let it rest and drove again this morning, the same symptoms emerged.
I got it up to operating temp and pulled the codes.
This time I got the same Code 22 (MAP/BARO sensor) and after a long pause followed by a single light I got Code 41 (System Indicates Lean R/No HO2S Switching Detected C)
Could my sensor be bad now that I have replaced my TPS?

This truck is 30 years old with 148K miles on it so I can understand that the sensors could be past their lifespan. I plan on installing a MAP sensor even though one was not in it and while I'm at it I am going to replace the 02 sensor since they are pretty inexpensive.

Oh!! one last variable I have is a cut in my intermediate exhaust pipe. It is past my cats and just before the resonator and I have done a shadetree repair with a stainless steel band. It still lets some air puff out however it is so far from the sensor I don't think that could be causing the issue.
That being said it was running terrible and burning coolant when I got it so I may just replace cats while i'm at it. I imagine at the very least they are completely fouled up.

Anyway I will update this thread once I get the work done. If anyone has any tips or information or jokes or anything at all please post ill just be here