bad MAF? 93 2.3L

[yonu]

Ok quick question I decided to test my MAF to see if it was the culprit of a problem I have been having and I think it is bad I am hoping someone can help me.

the base Vdc is 1.25-1.27 at idle as I rev the engine it goes to 1.35Vdc then to 1.68Vdc then to 2.5Vdc if I understand the testing procedure right I have a bad MAF does this sound about right?

Yes it jumps no inbetween voltages

Thanks,
Yonu

 

[RonD]

No, MAF seems OK

MAF is a "learned" sensor, because it's voltage will vary through out its life, there is no specific or exact voltage that is correct, it is a range, .5v to 5volts.
Read here for where to test voltages: http://www.therangerstation.com/tech_library/CleanMAF.shtml

Once you have an idle voltage, like 1.25v, then when you increase RPMs the voltage should increase, changes in voltage should be semi-steady and if you hold a higher RPM voltage should hold there as well.
You would expect above 3v at full throttle but not sure on a 2.3l, it draws less air than 3.0l or 4.0l, and voltage is air mass dependent.

Also clean the MAF and retest, if you haven't cleaned it yet.

And not sure on this statement: "Yes it jumps no inbetween voltages"

What are your symptoms in suspecting a MAF sensor issue?

 

[yonu]

The problem I am trying to solve is very low power it started this about 4 months ago and this is literally the last part I haven't changed.

Yes I did try cleaning it before I tested it.

As to "Yes it jumps no inbetween voltages" sorry I should have been more specific there are no readings between the voltages I provides my meter literally jumps from say 1.25 -1.35 or 1.68 there is no gradual increase in the reading. to make sure that it wasn't my meter I have used a analog meter and my good digital that does to the 4th decimal and it straight jumps voltages.

Here is the testing guide I used http://easyautodiagnostics.com/ford/4.9L-5.0L-5.8L/maf-sensor-tests-4

 

[Mark_88]

Did you check for slack in the throttle cable? It can be a long, slow process when the cable stretches...it will eventually snap sometimes, but rarely...

If there is ANY slack in the cable then try adding a few zip ties to remove the slack...works like a charm in most "losing power" situations...if it's not something like a plugged cat or carbon buildup...

 

[yonu]

will check the cable tomorrow

yonu

 

[Mikel89us]

As for testing the MAF you shouldn't test it for voltage. The fords use a frequency as a signal to the ecu. You should be measuring the sensor output in hertz.

 

[yonu]

The throttle cable is fine. the catalytic is fine I put a new one on aabout 4 months ago as the heat-shield had came apart on the old one. so guess I am back to square one unless someone can suggest a proper method for testing the MAF.

Thanks,
Yonu

 

[RonD]

You put on a new catalytic converter on 4 months ago?

And you started losing power 4 months ago?

The problem I am trying to solve is very low power it started this about 4 months ago and this is literally the last part I haven't changed.

An engine is an air pump, sucks air in and pushes air out.
If you were to cover the air intake you would lose power
If you were to block the air output you would lose power

If your cat was bad then muffler could be as well, which blocks the "air output".
Feel the tail pipe flow as someone REVs the engine, make sure you have strong hard flow out the tail pipe.
As the RPMs go up so should the flow, if it doesn't increase as much as the RPMs then you have blockage.
Vacuum gauge can test for this as well.

That could also explain the odd MAF voltages, air being pulled in is being blocked because air can't get out, flow at MAF is not linear it is pausing.

 

[yonu]

sorry the power issue started before I changed the cat but not by much the only sad thing is I didn't change change the cat for the power issue.

yonu

 

[tomw]

I would check fuel pressure and volume. The MAF will show as hesitation on acceleration in a lot of cases. Lack of fuel would lead to lack of power.
Have you checked the pressure and delivery volume? It could need a new filter, regulator or pump if there is a problem.
tom

 

[Mark_88]

The throttle cable is fine. the catalytic is fine I put a new one on aabout 4 months ago as the heat-shield had came apart on the old one.

Thanks,
Yonu

OK, thanks for the feedback...it helps to eliminate some of the more obvious causes...

Did you, by any chance, try pulling codes?

 

[tomw]

For those who have loose shields on their catalytic converters, read:

I used 4 stainless steel 'screw clamps' from Home Depot to tighten up a shaky shield. Use two clamps, head to tail, to gain enough length to reach all the way around the shields & converter, and tighten in place. Repeat for the second pair of clamps placed where you think they'll hold tight. Over time, the clamps may need to be tightened a bit from vibration or more clamp deterioration, but the clamps WILL tighten up and eliminate the noise of rattling shields. In my case, the converter itself was fine internally, but made noise at certain engine rpms.
tom

 

[yonu]

as to trouble codes I havn't gotten a trouble code since I changed out the coolant temperature sensor. I did a fuel pressure test and get between 31-39psi as I rev the engine does this help?

yonu

 

[yonu]

I did notice while I had my hand back there that the vacuum hose from the throttle body had split and came off of I changed that hopefully it will help

Yonu

 

[Mark_88]

Well, I just went to the top of the thread to see what you posted originally...and don't recall seeing anything about symptoms...but a broken vacuum line (or even one with a hole in it) can give you all kinds of problems...won't idle properly...sensors usually off so you eventually get codes (which you said you haven't gotten) and just poor response over all...

So, yeah, fix that hose and see if it's any better...maybe post more symptoms as to what it's doing more specifically (if you didn't already...that is...)