Hey guys! New guy here looks like a lot of great info here! So here is the problem, 93 2.3 ranger will only run with maf unplugged. With it plugged in, it starts and dies right away. I took the computer apart and it looked good to me anyways. Only codes I get are a 157 and 159. If I start it with the maf unplugged, it will run and when I unplug the IAC the idle goes to crap and wants to die. I took the IAC off but left it plugged in and I don’t see it move at all when I start it.
I have to plug the driver side port hole on the back of the throttle body with my finger or it will die without it connected. But the fact that idle goes to crap and wants to die with it unplugged tells me it’s good. Fuel pressure is 40 after I turn key and is about 35 psi running so I don’t think it’s a fuel issue. Also I dont think it’s a fuel issue because it will run. I did put a new Maf on it and it still does the same thing. All vacuum hoses look good. I don’t want to start throwing parts at it and I don’t know what to do! Help!

 

Have you put a vacuum gauge to it? I would start there.

second I would check the continuity of the MAF plug wires. maybe there's a short on one of the wires.

 

I’d love to check the continuity of the wires but I have no idea where they go/where the ends are.

 

I should add, the only codes I get are a 157 and 159 for maf. Can I check codes with engine running? And how do I test the maf sensor harness?

 

Try this link;
https://easyautodiagnostics.com/ford...nostic-tests-1
Read through it and decide if it can help or not.

 

Thanks for the link. So I tested the maf according to the link. The red power wire has 12 volts and the black wire/chassis ground checks out good. While checking for ground to PCM with the tan/blue wire, it says to have the key turned to on. For this test, I’m only getting 7 volts but with the key off, I get 12. Now I wonder if the PCM is bad? I cannot check the fourth wire because it will not run with maf sensor hooked up.

 

I should add, that ground to pcm wire and that fourth wire all passed the continuity test to the pins on the PCM. I also checked for vacuum leaks with propane and all checked out fine.

 

I'm just guessing, but I doubt a 5v drop with the key on would be considered normal, but I don't know for sure.
RonD seems to be the most knowledgeable here, I'm sure he'll respond at some point and help you.

 

Many times a corroded or damaged wire will pass a continuity test while causing a large volt drop when energized resulting in component failure. The wire only needs a strand or two intact to pass a continuity test, but when energized will have a high resistance to current flow.
I don't know if that's your issue, but it's a possibility.

 

What i would do is get a wire piercing probe.

pierce the PCM ground wire at the MAF plug and ground it.

then try to start the car with the MAF plugged in.


My 92 ranger had an issue with the PCM ground for the fuel relay. no matter what i did the PCM wouldn't ground correct and would never activate the relay until i spliced in a ground to that wire. now the car runs fine.

 

Thanks for the advice. Just tried it. Had 12volts with key turned to on. Started it. And it died right away. ☹️

 

Maf is shot. Replace it!

 

I already tried that.

 

This might not be relevant but a lot of aftermarket parts that are listed as "OEM Replacement", aren't. It's often hit or miss. I'm not saying to go out and buy another MAF sensor, just keep in mind that "new" doesn't always equal "working" or compatible.
As an example: I replaced the original Motorcraft IAC valve for my 2000 Ranger 2.5l with the Hitachi valve that was supposed to be the proper replacement. After almost a year of RPM surging between gears and at stops, along with a constant CEL and a code I decided to put the old Motorcraft back on. (I had kept it and cleaned it prior to buying the Hitachi, but figured
it was probably time for a new one anyway so I went with the Hitachi). As soon as I reinstalled the old IAC everything went back to normal. I wish I had followed my instinct and put it back on sooner, it would have saved me the $200 for a smoke machine to track down the non existent vacuum leak I thought I must have had and a whole lot of headache.

Did that link I posted have a test procedure for the MAF itself? Like I said, I didn't read through it. If not I can try to find a specific procedure to test the MAF, if there is one, I can't remember off hand.
I was lucky, my MAF just needed to be cleaned with MAF cleaner.

Another thought; if you know someone with a good bi-directional scan tool. or a garage you trust, you might just have them throw the scan tool on it and see in real time what it's doing, or not doing. Then go from there. The price for a good scan will probably be cheaper than loading up the parts cannon.
I hope you get it figured out.

 

Thanks for the reply. It was a Walker brand maf from rock auto. I installed it, no luck, took it back out and sprayed with maf cleaner, still no luck. I took the backing plate off on the maf sensor port as well and it was clean. The testing procedure showed all 4 wires. 3 wires checked out good. The only wire I couldn’t test was the maf signal wire because it has to be plugged in and running for that, and it won’t run with it plugged in.

 

Got a vacuum gauge. FPR looks good. EGR is working as well. I don’t see any vacuum leaks.

 

Check out this video by ScannerDanner.

Although he's referring to a GM MAF sensor, some of the information is relevant to MAFs in general.

 

Here's another video where ScannerDanner tests a MAF on a Ford Explorer, showing some testing and values.

 

Just wanted to post the fix! After checking out sensors and what not, I decided to check codes again. Now I am getting a 543 code. Something about a fuel pump secondary ground or something. I have 31 psi at fuel rail and that jumps to 40 if I unplug the vac line on the fuel pump regulator. So there is no fuel issue. I replaced the PCM with a different one from a local pick a part. Fired up and runs great! No check engine lights either! Thanks for the help folks!

 

Good to hear you fixed the issue.

 

I've been having some issues with my 1993 ranger and wanted some advice.

As I was driving at highway speeds, I noticed it started to struggle and misfire... very lumpy and chugging while idling, pedal to the floor and its not accelerating and struggles to get up to any speed over 60km/h.
I ran a code reader on it and it read error 159, MAF +/-. I had it replaced and the performance immediately DECREASED so I put it back on and it improved, but still significantly worse performance than normal and the CEL light is still on.
I have also recently changed the fuel filter and O2 sensors.

Any suggestions for further trouble shooting?

 

Hi,
I have no experience with an OBD1 2.3L engine so I'll post some links for you that hopefully get you started toward a solution.
Here's one for a 93 Ranger with the 4.0L engine but the MAF code should be the same.

https://www.ford-trucks.com/forums/1...ode-159-a.html

A couple of points were made in the replies:
1- The 159 code is different depending on which test is performed. Key On Engine Off or Key On Engine Running and both are listed.
2- The OP later states the truck seemed to run better with the MAF Unplugged, much like the OP here.

Here's a list of Ford OBD1 3 Digit codes

https://www.therangerstation.com/tec...3-digit-codes/

But to get you started you might want to check cylinder compression. You'll need a compression tester.
It's always a good idea to start with compression before throwing parts at a problem.
I'm pretty sure each cylinder should be around 150psi but it's more important that they all be within 10-20% of each other. For instance- If 3 cylinders read ~ 140psi and the other reads 100psi or lower, you have a problem.
Other issues could be:
Timing- The timing belt could have stretched and slipped a tooth or two resulting in incorrect timing.
Note- If your timing belt has over 75,000 miles on it, it's only a matter of time before it fails ie breaks. The 2.3 is a Non-Interference engine just like my 2.5L so "when" it breaks there won't be any valve to piston contact hence the "Non"- Interference designation. But it's best to just change it before it breaks if it hasn't been changed and save yourself a tow charge, trust me on that.

Exhaust- Your Catalytic converter could be clogged.

Fuel- You could have a bad ground or faulty pump.
Or bad gas ( old gas or high water content ) can be an issue.

There are other things you can check but these should give you a starting point until someone more knowledgeable responds.

 

Thanks so much for following up! A couple updates to add that may be relevant:

I returned the 'new' MAF and installed a new, American made one and it's performance improved immediately. I also cleaned the IAC and butterfly valve on the throttle body. The CEL light went off but then returned a day later, reading codes 159, 177 and 185. Upon further inspection, the mechanic I had taken it to previously had only replaced one O2 sensor, so I replaced the other old one. Since doing so, the performance DECRESED (losing power at high speeds and going up hills) and is still throwing the same 159, 177 and 185 codes.

I'm very shocked by the results as the O2 sensor I replaced last night was original to the engine, so over 31 years old. The O2 sensor my mechanic installed was an NTK and the one I installed was a Delphi, could the brands be conflicting? Could a faulty fuel pump be causing both the MAF and O2 sensors to not run properly?

The mystery continues........

 

If the mechanic only changed one, was it the pre-cat (upstream) o2 sensor? The post cat (downstream) o2 sensor usually lasts longer under normal conditions, but they're all considered consumable and will wear out after a certain time or mileage. When changing anything like an o2 sensor I would think it's usually better to get them from the same company.
Keep in mind that there are different types of o2 sensors, and some engines will take the same part number for both upstream and downstream while others require different part numbers for each. Some engines take 4 sensors, while some older engines with a Y pipe apparently only have one.

Today's market for aftermarket parts is hit or miss, and more often it's a miss. It's common now to get bad parts right out of the box, even several back to back. If you happen to be friendly with a good mechanic or garage owner familiar with Ford Rangers, maybe you can talk to him/her.
As far as the forum here, Ron D is a wealth of information. I'm surprised he hasn't replied yet, but I'm sure he will at some point.
Until then, have you searched the forum for your engine/year/problem yet? I'm sure at least a few threads with posts from Ron should come up in the search.