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This is my first post and I am looking for some advice. 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.
Empty hole behind plastic cover Cover where MAP/BARO sensor would be
i would appreciate any advice/tips.
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.
oh 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.
Each should have 3 wires and one is a Brown/white wire, that's a 5volt wire from computer pin 26 it "powers" both
Since you are getting codes 22 and 23 then there could be a problem with this 5volts
That can be caused by bad capacitors in the computer, after 20+ years they fail and leak causing running issues
Free to open computer and have a look, there should be 2 or 3 Blue capacitors, have a close look at them and under them
Just replace my 1994's 3 caps(june 2020) and issues I was having are gone
And could just be a corroded connection on pin 26, causing a voltage drop
Yes, input voltage at the TPS should be 5volts and then output voltage at closed throttle .69-.99volt, and wide open 4.5+volts, so you are reading lower voltage than you should but that may be an input voltage issue not a TPS issue
BMAP sensor was used just for local air pressure, i.e. at sea level or in Denver, 5,000ft elevation(thinner air), so wasn't connected to the intake manifold vacuum like a MAP sensor was
In later models BMAP wasn't used since it was found that the MAF sensor could compensate for "thinner air" at higher elevations
3rd PDF has TPS and BMAP wiring, but thought you should have all 3
You will see the Grey/red stripe wire as well, all sensors share this wire, its a ground reference wire hooked to computer pin 46
The sensors work by the difference between pins 26 and 46, so the EXACT voltage is not a big deal within reason, i.e. 4.8volt to 5.2volt on pin 26 is fine as pin 46 would have the same off-set from 5volts
Hey Ron, thank you for that detailed response!
I checked the voltages of all sensors and they were as follows:
TPS 5.0v
MAF 11.98
BMAP 5.0v
It seems they are all receiving enough power, so it may be the sensor that's at fault. I ordered a Motorcraft TPS and will install it when it arrives in a couple weeks.
Judging by the pictures I posted do you think someone has removed the BMAP? Would it be advisable to buy a completely new sensor and instll it to get rid of the trouble codes?
Also I forgot to mention but the previous owner replaced the computer. I don't remember what he said caused a failure (water damage maybe?)but there is a new computer installed
I cross referenced it to the Fuelinjectedford website you posted (thank you for that!!) and the three digit code is not listed. My computer is F17F-12A650-FA X1L
I looked on every vehicle but there was no X1L code on the sheet.... Could I have an incorrect EEC?
Hmm that is slightly concerning then. Mine is definitely X1L so it may be an incorrect computer.
i will retest the MAF soon and see what the actual voltage is. If the new TPS does not help I will look into a replacement eec.
i actually have the old eec here as well (F17F-12A650-JA A1S) so maybe I will plug it in and see if it helps at all.
thank you for all the help so far!
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 reading responses.
Thank you RonD, your knowledge is incredible and I would not be making nearly as much progress without it!! Your next drink is on me (once covid is over of course)
I put in the Motorcraft MAP sensor and replaced my O2 sensor with a brand new bosch sensor and all i well!
I reset my computer and drove around for about an hour to let things get calibrated. Check engine light came on once after about 20 minutes of driving but when I turned off the car and started it back up it went away.
Since then it has not come on a single time!
An interesting note: I went for a spin after only replacing MAP sensor (with old 02 sensor still in) and the 3krpm shakes I was getting changed. They were slower but more pronounced. After replacing 02 sensor I get the familiar shakes I had when I bought the truck.
This makes me think the shakes are being cause by an air/fuel problem. I still have cut up cats so I'm thinking they are backing up flow and causing the issue.
I had a shake on my 4.0l above certain RPMs, and it turned out to be the Fan clutch, going out of balance
Engine off, wiggle fan, shouldn't wiggle at all
You can use a vacuum gauge to test for clogged exhaust
Hook it up
Start engine, should see 18-21" of vacuum
Raise RPM to 2,000 or so and hold there, vacuum should settle in above 15" or so, and stay, if its slowly dropping then exhaust is clogged, backing up into engine, so vacuum starts to go down
Silly me. I replaced the computer with the "broken" computer the previous owner had taken out and guess what, literally everything was fixed!
The previous owner must have purchased an incorrect ECU and installed it. All 3krpm shakes are gone and the amount of power I now get it unbelievable! (I imagine this is what a 5.0 swap feels like )
Anyway I was getting only 12-13 miles per gallon before the comp swap so I am going to fill up my tank today and see if I get some better mileage with the new computer.
Thank you RON for your infinite ranger wisdom. I wish I would've tested the old computer sooner. I admit the weathered look of the ECU case and the previous owner's word made me doubt it worked at all. I guess I learned to always double check anything a PO says
Anyway I will update in a couple weeks on how it's running just for forum records (should any other weary soul finds themselves in a similar situation)
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