Since those things cost about 109 bucks, I wonder if there is a way to test them. I guess I can get my 30 bucks back for the core charge, but that's still 70 dollars for a piece of equipment that is fairly critical to fuel/air ratio - and its as delicate as all get out to boot

So any ideas on how you might test one?

 

Well my MAF went bad with no code, I tried cleaning the MAF with Electronic cleaner what leaves no residue without luck. I was like you I wanted to test it to see if it was the problem before I put out $$$$. I tested it to what the manual said but????? It tested out ok but I went ahead and replacest it anyway and the truck ran much better. Some mechanic said to me sometimes they just fade down without putting out a code and when it gets to bad it will put out a code. My truck is a 93 4.0L. I hope I was some help

 

The answer to the question is found in a "real" service manual, such as a Ford factory service manual or Alldata. It involves a voltage check; no biggie. The thing to consider as we talk about MAF sensors is the basic principle in how they work. Basically, there is a heated element upwind and a thermometer strip downwind. By observing the temp on the downwind strip for a fixed voltage on the heater (ie, known rate of heat being generated and expressed in BTU'S), the rate of airflow can be determined. So when these two strips get dirty it can now be understood what will come next, given what I just said. The typical result is an airflow less than actual is detected; the ECM responds by leaning out the A/F ratio at a time that is inappropriate, and you get engine knock.

*beware of cleaning MAF's with electrical contact cleaner; best to use brake cleaner or carb/fi cleaner.

 

All due respect I think you have that backwards CowboyBilly9Mile. carb/fi cleaners will destroy MAF sensors and brake fluid just make sure its not chlorinated and leaves no residue.
Electrical contact cleaners that leaves no residue is the way to go. Carb/fi cleaners I would think is to harsh on the element and I have heard people destroying there MAF’s using Carb/fi cleaners.

 

MAF Testing

Pull the MAF electrical connector & make sure there is battery voltage & ground connections at the wiring harness connector.

Check the MAF elements for continuity, if it reads infinite resistance, the MAF element is open, or it's electrical connections are bad.

If all that checks out ok, plug the wiring connector back in & back probe the MAF SIG & MAF SIG RETURN wires for voltage. It should be about 0.2-1.5 volts DC at idle rpm.

Increase the engine RPM to the value you normally see on your Tach, at say 60 mph & monitor the previous voltage readings, it should increase slightly, to about 2.0 VDC at the increased RPM.

If that checks out ok, the MAF is probably ok.

You could try shuting down the engine, disconnecting the MAF, restarting he engine & see how it does, with the MAF disconnected. If it's better, then the MAF is likely still dirty, or it's out of tolerance & needs to be replaced.

Another way to check it's operation, is to monitor it's operation with a "scan tool", that'll monitor live feeds from the MAF to the computer, as you drive.

If you don't have any MAF trouble codes, saying the computer is unhappy with the MAF's inputs, it's lkely ok, imo.

Just some more thoughts on the subject.

 

If possible, you can do an "MAF snap test" which supposedly is a more accurate way of testing the sensor in action.

 

Well I do appreciate all your inputs on this, its something that I hope gets filed away in the forums' technical library sticky thing.

As to my plight, I just replaced the damn thing. At 109 bucks it wasn't worth it me to fuss with it. I guess I'm gonna write this whole dang thing off as the 100k mile sensor replacement spree.

I'm still looking for a good line to use to insert the Seafoam into the intake manifold. The sticky mentioned the evaporator line but I'm still eyeballing the PCV line.


One thing that strikes me that tells me this is probably a bad sensor or part. The problem goes away for a while when I reset the computer. To me that smacks of a bad sensor. The computer gets reset, then the bad sensor slowly fills the data tables with bad input which is making the computer slowly retard the timing back the value that causes the pinging. But I'll be damned if I can figure out which one it is.

 

The easiest way to get a quick look at your MAF sensor's condition is to access the BARO PID on a scanner. At sea level, the BARO PID should read around 157hz with the ignition key "on" and the engine "off". You will have to adjust for barometric pressure in your area. If your MAF sensor is failing, the BARO reading will be significantly lower than actual barometric pressure in your area.

 

Well you could use the brake booster vacuum hose to feed the Seafoam in.

I like to use one of those metal sport inflation needles, attached to the hose that goes into the Seafoam, so that it's less likely to suck in too much Seafoam liquid, too fast & hydrolock the engine & bend something up!!!! lol

You'll probably want to consider pulling the plugs & clean them afterward, a well as change the oil & oil filter, as both will likely be loaded up with "stuff"!!!!
Just some more toughts.

BTW, did the new MAF fix things up???

 

Nope, if anything its worse now. I'm at the end of my rope with this frickin' pinging problem. I'm so desperate I might actually take it to the <gulp!> dealer to have them look at it.

We'll see what the Seafoam does for me and take it from there. I have to wait until my buddy get's back from his Guard duty so I have someone to goose the pedal when the engine starts to grumble about all that Seafoam.

 

I assume you are thinking you have a carbon problem, hence the Seafoam. Just running it thru a running engine does little to help this problem, and if you do have this problem, Seafoam is the wrong product. GM makes the best upper cylinder cleaner. It has some nasty stuff in it. Seafoam is mostly napthene. A little searching should give you the part number, or you can call a GM dealer parts dept. For this stuff to work, including the Seafoam, you flood the engine until it dies, then let it soak overnight.

Modern engines usually don't carbon up bad enough to cause a problem unless you have bad driving habits, or a problem with the engine. Many times, a hard run thru the gears peaking engine rpm will help about as much as anything. "Blowing the soot out of it" as they used to say. jd

 

Have you searched closely for vacuum leaks????

 

There aren't any vacuum leaks that I could detect.

Like I said, if this is such a complicated issue that I can't figure it out doing simple maintenance and replacement of suspect parts - then it's a job for the dealer.

This particular Ranger has always had intermittant pinging issues, one of the reasons I switched to 91 octane for so long. The problem went away using it. But now not even that is curing it, indicating a very real underlying problem that the 91 octane masked but needs/should have been fixed. I have two choices, let the dealer take care of it or trade it in. I've had my eye on a new Dakota for a while, but that would end my 16 year streak with Rangers.

I have to get to work reliably, and I ain't gonna fuss with it anymore. Sorry Ford.

 

Actually, some electrical contact cleaners, depending on the brand, leave a lubricant that can attract dirt. One must read the label very carefully. I've never personally heard of anyone destroying a MAF sensor using the "wrong" cleaner, but myself and the few that have done it have used a fine artist brush and a small quantity of cleaner in a bottle to gently remove debris. Patience is needed when doing this as a guy doesn't want to aggressively try to take care of cleaning in a few seconds; said another way, time spent doing this is a good thing. I have seen MAF's destroyed by rough cleaning.

 

Well running 91 octane in it, to stop the ping, was sorta like retarding the ignition, as 91 has a slower flame front it burns more slowly, so in an engine not designed to use it, over time, the 91 octane could have carboned up the combustion chamber.

If it's not too bad, the Seafoam may clean it up, but Chevrons Techron Consentrate, in a tank of Chevron gas would likely do as well, or maybe better, as it won't dirty up the plugs or oil & filter.

Even if you get it decarboned, you need to find out whats wrong.

It's gotta be timing, or fuel trim, seems to me & with it squaring away for a while after you pull the battery cables, seems to me that kinda points to a fuel trim, or vacuum leak problem.

With it running worse with the new MAF, makes me wonder if it was a aftermarket MAF????? If it was a aftermarket product, it's opeation response time profile, might not be the same as Fords spec for their MAF.

If you could come by, or make loan of, a good scan tool, that can read PID's, you might be able to spot the problem, by monitoring different sensors having to do with fuel trim, like the MAF, injector pulse width changes, fuel pressure, manafold vacuum, computer engine temp sensor, inlet air temperature, ect, ect. Maybe you could spot something working, but out of tolerace.

With the mileage you have on this ride, the O2 sensors would also be on the suspect list. They could be working, but lazy!!!! If you've replaced the O2 sensors with aftermarket ones, the same kinds of problems may arise as the MAF operation profile ones I mentioned.

If you have plugs of wrong design or heat range in the engine, it may protest.

If your ignition system is the "waste spark" design, you'll need the double platinum plugs. I'm not a 4 banger guy, so I'm not sure which system your 4 banger is, but your owners manual would list the proper plug for this engine.

Just more thoughts for pondeing.