93 Ford Ranger 2wd, Manuel, not sure how many miles, the odometer has turned over but honestly not sure how many times. So, it could be 135,000 or 235,000 or 335,000. I've owned the vehicle for 7 years and absolutely very few problems. I'm going to tell the entire story of what has happened, some things may seem irrelevant but I want to cover everything since you never know what may spark a reason for what is happening. I am admittingly an amateur in automotive work but enjoy working on my vehicles and believe in if you want something done right do it yourself.

Problem: Vehicle stalls while driving. It doesn't matter if I am accelerating, decelerating, coasting, etc. It just stalls seemingly random. To restart the vehicle I have to turn the key all the way back to the "lock" position and then restart the vehicle, which it does the first time without issue. If I do not turn it back to the lock position and just attempt to restart it from the on position the vehicle will just turn over without starting but as soon as I turn it off/lock and restart it, it fires right back up. The vehicle runs fine at idle whether cold or hot other than the surging or oscillating up and down which it has always done since I have owned it and nobody can seem to tell me why it does that. I have taken it to numerous mechanics to try and get an answer as to why it oscillates but none have been able to tell me. I put a code reader on it and it threw the codes 157, 218, 222, 223, 224. 157: MAF-low voltage. 218, 222, 223, 224: IDM codes (Ignition Diagnostic Module) which mechanics don't know what I'm talking about when I say IDM, though that is what the code book calls it, mechanics call it the ICM (Ignition Control Module). Anyway, I changed out the ICM (using dielectric grease) and it still threw the same codes. I changed the MAF and all the codes cleared and now all it throws is codes 10 and 111. NOTE: Since changing the fore mentioned parts the vehicle runs noticeably better. It seems to have increased HP and just feels and sounds like it runs better. It also does not stall nearly as much. It was stalling once or twice every hundred yards but now it will stall maybe once or twice every 100 yards but then it can run fine without issue for five miles. When it stalls it kind of flutters to a stall and no matter what I do such as pumping the gas, it will not run until I restart it. It also will sometimes backfire when it stalls but not every time.
LEADING UP TO THE PROBLEMS: The water pump is leaking which I was going to replace but haven't yet due to the stalling. I had to replace the "Idler pulley", the bypass pulley where the power steering would be. It originally had a 5.25" pulley on it. It broke off and went flying down the road somewhere. The belt stayed on the spacer and continued to work while I drove three blocks further to get home. At that point I knew something had happened but did not know that the pulley had broke completely off. The only replacement I could find anywhere was a 3.25" pulley and left the same size belt on it.
I changed the oil and overfilled by less than a qt. The problems started right after the oil change. It started out filling like an engine does when you overfill it with oil. I drained the excess oil out as soon as I knew the problem existed. (Reason mentioning this is because my thought is that I may have clogged the catalytic converter???)

I have checked for vacuum leaks and do not detect any. I am going to check the relays and ground next. I know the failure of other sensors can cause these same issues but shouldn't a failure of a sensor throw a code? Any other suggestions or people who have ran into this problem? I have read other threads that said their PCM was bad. I haven't checked that as of yet.
Also, I have only checked the spark plugs and wires for spark, which all 8 do at least spark.
Any help would be greatly appreciated and any suggestions. I'm not going to give up on this truck. This is the best vehicle I have ever owned! I am going to drive it until it or I are absolutely dead.

 

Welcome to the forum

Because of the amount of trouble codes I would pull out the computer and have a look at the circuit board

There are 2 or 3 capacitors that will leak after 20+ years and cause issues in the computer, they are easy to see and change, under $5 fix
Picture here: Ford EEC-IV

there are 3 Blue "barrel type" capacitors seen, they can also be black and there can be 2 or 3 of them
You need to replace these regardless, when the computer is out because they WILL fail, 100%
Each has a uF value on it, and a Voltage
You need to match uF exactly but can use a higher voltage if thats all thats available, i.e. if cap is 16uF and 20v then you can use a 16uF 100v
Do not use a lower voltage
Take pictures of board and cap values, and orientation, Caps have a + and - side, there is a stripe on one side for "-"

Images here of bad caps: Capacitor Repair: Ford A9L ECM « Moates Support
Caps are at different locations and different uF values even in the same years
You can get Ford Capacitor replacement kits, they come with several caps(4 or 5) that may work on yours, but may be missing a value you need

Also check the pins and slots on the 60-wire connector, clean as you see fit
And clean any corrosion on the circuit board
And di-electric grease is used because it DOES NOT conduct electricity so won't cause shorts, BUT....................
You do not want it ON the pins or IN the slots where electricity NEEDS to be conducted
Most of the sensors use UNDER 5 volts, so need a good connection to give the computer a valid voltage reading for that system

If you have 1 code, or maybe 2, that can be a system issue, but when it gets above 3 codes you should first check the source, the computer, if its OK then you can chase down each system code

 

Ron,
Thank you for the reply and all the information, that is great!. I will pull the computer today and take a look but I'm willing to bet that you are right. I don't mind that I replaced parts because fact is, they were probably due for a replacement anyway after almost 30 years. I can't complain about that.

A question, just so I can better understand the workings for future diagnosis. If it is turns out to be the computer, how come after I changed the ICM and the MAF the codes cleared? I get the fact that if it is the computer the computer may not necessarily throw codes to show that it is bad because it can't, something has gone wrong with it and it may not be able to send the codes indicating that it, itself is bad. Or, is it because what is currently wrong with the computer, it may have been telling itself that the ICM and MAF were the problems and now it sees them as fixed so it clears the codes? ( I think I just confused myself-lol) I hope that makes sense.
It only stands to reason that after almost 30 years the capacitors would go bad. Hell, even I had to have some things operated on to clear out the old junk by 30-lol. I'm just trying to make sense of how the computer works to better understand the working of a vehicle.

Thanks again for the reply! It really helps me as well as others who might have the same or similar problem in the future. These old Rangers are fantastic trucks!

 

1989-1994 2.3l ICMs are a known issue so, yes, if there is misfires or running issues, and no starts after ICM is hot, then that would be the first stop
And ICMs can be tested, but they can still be bad, even if they test "good", lol
They are much like Coils or Coil Packs in that regard, you can test them and they can pass all the tests and still cause misfires after they heat up

If the pre-1995 computer has never been touched then when there are multiple codes that's were you should start just to take it off the table
Because computer can cause intermittent issues, so you replace a part and it seems to run better, then similar issue comes back or another issue, and it can keep you chasing your tail for weeks, months, even years, lol
Its like you don't have a Ford Truck anymore, its now a wanna be "Chevy" :)

Computer may be fine, or maybe the issue, no crystal ball here


If you have misfires on an older engine you should do a compression test first, just to take burnt exhaust valves off the table, it's the most common cause of misfires in older engines
You can change spark plugs and wires first, these DO wear out, and new spark plugs may get less or no misfires for a bit, problem may or may not be solved
But doing the compression test first tells you if its a mechanical issue or a spark/fuel issue, not really a "grey area" with mechanical issues, lol

And if you are going to change spark plugs anyway...................might as well test compression while one sides(2.3l) spark plugs are out

 

Thanks again for the reply. I pulled the computer today and I'm surprised at how good it looks. Looks to me like it is brand new. Visibly, and I know a visible check is no where near definitive, I cannot see any signs of anything wrong, no scorch marks, no bulging, no leaks etc. I am going to put the new one in as soon as it gets here and see if that clears up the issue. I will post the results here in hopes that it will help the next person but if not, then onto the next step.

 

I have the same problem! I'd appreciate if you could reply to update if the new computer fixed yours, I know your 4cyl 2.3 is much different than my v6 4.0L but they're the same years and same exact problem and I've replaced a bunch of sensors and mine has the same idle you explained and it started to act up after I did an oil change slightly overfilled like you explained and I'm giving up thinking of bringing it to the shop next week but if I'm able to fix it myself I would be so happy since it's had this problem since I bought it and the previous owner just said it needed an egr valve but mine doesn't even have one, it has bad egr valve symptoms though Lol