MAFS testing

[Xeek]

ive come down to this as one of the things that possibly causing my problems.
i tried this method awhile back, early '11.: http://ford40.com/sputtering.shtml

whats the proper testing with a voltmeter?
A: solid red - B: black w/white - C: tan w/black - D: light blue w/red
ABCD is labeled on the sensor itself and those are the color wires going to each pin.

which ones do i want and what reading am i looking for?

 

[jd4242]

I think its a FI bleeding off!!

 

[Xeek]

i havent heard it doing it anymore. but it may be due to the awkward position i need to get into to turn the key and get my head in the engine bay to listen.

but this test cant hurt. stalling in cold weather leads me to the mafs.

 

[Xeek]

no one knows the way to test it?

 

[Xeek]

i found this by a stroke of luck seaching youtube



doing that, after revving to get the truck to not stall, the voltage jumps around from 0.02-0.04 at idle(600rpm). revving all the way to 3k rpm does nothing except when i let go itll hit 0.01 then go back to 0.02-0.04.
so im pretty sure this is the problem

 

[Xeek]

got one from the junkyard, same issue. tested it and it jumps all over the place between 0.01V-0.10V at a 750-800rpm idle, revving doesnt do anything, it still jumps.

unplugged it and started, idled nicely at 1000rpm, cel for it being unplugged.
put it back in and it idled at 800rpm smoothly with a warm engine. if i had driven it cel #41 wouldve came back and it wouldve stalled if it was cold.


i think i may go for the wire harness. i wanted to replace it anyway as the old owner has it hacked up to fix shorts in the coilpack and blower motor(loose wires not even tucked into the loom at all). and a couple spliced pigtails.
lets say i wanted to test continuity on the wires, where do i tap the other end? at the pcm? i would need specifics on what colors/pins im after.

 

[2000StreetRod]

MAFS PCM pins

My Haynes manual shows two different pinouts for the 60 pin PCM connector.

For 1994 & 1995:
MAFS signal - pin 50 (LB/R)
MAFS return - pin 9 (T/LB)

For 1991 thru 1993:
MAFS signal - pin 15 (T/LB)
MAFS return - pin 14 (T/LB)

 

[FIND]

Wow.... That is one of the worst, most misinformed sites I have ever seen on the internet. Most politician's websites don't have as much misinformation as you find on there.... Black paint on your bumper to avoid speed traps? 10 HP for cutting a hole in the inner fender? A K&N panel filter giving you more power and fuel economy? Parts store thermostats are 212 degree t-stats?

wow.... just wow.

BTW Xeek, your MAF sounds fine to me, though, I think you were testing on the wrong pins to get the numbers you got. Have you tested your IAT? What about JD's thought, an injector bleeding off. Any of your plugs getting significantly more fouled than the others? You should think about having your injectors cleaned and tested.

 

[Xeek]

lol. yea that site is odd, but the maf cleaning seemed reasonable.

my tps and iac are new. unless i wasnt getting a good enough connection, the voltage is supposed to rise evenly with throttle, not jump around like crazy. all my plugs were fine, except #2 and #3(rear and middle, ac box side). but that was due to bad plug wires.

when me and jd tested my wires he noticed an injector sounding like it bled into the cylinder after they all clicked. i havent heard it at all recently, but there is one 'click' thats longer and sounds a little different, but its not the same sound as before.
and my injectors are brand new, flow matched, 3 nozzle sprayers. went in with the engine build. so i doubt theyd be dirty unless one was damaged during shipping. or it got clogged from my fuel lines being open with duct tape wrapped around them while the fuel rail was off for 2 months.




edit: you said iat not iac. the temp sensor right? if so, all ive done was clean it with brake cleaner when i rebuilt the engine.

 

[boominXplorer]

Unless you are using a Fluke multimeter your voltage will jump all over the place. Cheaper multimeters do not have the ability to read potentiometers and voltage spikes correctly.

 

[Xeek]

Well if that's the case, then there goes that plan. Don't know the brand but its a $20 digital one from autozone.

 

[FIND]

Yeah, IAT, the temp sensor. Somewhere on here is a chart for testing it, I'll see if I can find it later. Is it sputtering at all RPMs?

 

[Xeek]

its fine. when the engines cold, i ahve to hold the throttle for ~5mins or else itll just stall. above 800rpm works good for that. when its finished trying to stall and i let it idle, it stays at 600-ish rpm and shakes the truck, then rises to 1k rpm slowly for a minute then back down to 650rpm quickly and stays there with not as much shaking.
after driving and coming to a stop itll idle in drive at 850rpm, sometimes itll stick at 1k rpm.

i went and bought a iat sensor for the hell of it on my way home today. gonna let it cool off a bit then go test my current one. if its bad ill replace it, if not ill save it for later.

 

[Marv]

Try this one:

http://easyautodiagnostics.com/ford_maf/maf_sensor_ford_1.php

 

[FIND]

its fine. when the engines cold, i ahve to hold the throttle for ~5mins or else itll just stall. above 800rpm works good for that. when its finished trying to stall and i let it idle, it stays at 600-ish rpm and shakes the truck, then rises to 1k rpm slowly for a minute then back down to 650rpm quickly and stays there with not as much shaking.
after driving and coming to a stop itll idle in drive at 850rpm, sometimes itll stick at 1k rpm.

i went and bought a iat sensor for the hell of it on my way home today. gonna let it cool off a bit then go test my current one. if its bad ill replace it, if not ill save it for later.

that is sounding a little more like a bad ECT sensor..... but the warm idle issue you are seeing is kind doesn't really fit. I would ask about vacuum issues, but I'm sure that is the first thing you checked. ECT and IAT you can just check resistance. In my experience, the only thing that will throw a code on either of them is if you have a closed circuit or infinite continuity. They never seem to throw a code for when they are just a "little" broken, unlike the TPS, which is good at throwing codes.

That cam you use isn't even that aggressive over stock, so I wouldn't think that is the culprit either....

EDIT

This is accurate for ECTs in our Explorers and for in F-150s

This one should be accurate for our IATs

 

[jd4242]

Could be true.maybe you messed up the senor with the efan.

 

[Xeek]

new results. i put the new iat in last night, reset the battery.

got in this morning(30*F) and had to throttle to keep it on again. then not but 1 mile of driveing, CEL light came on. coming to lights it idled at 1k rpm.
when i got to work and put it in park it jumped to 2k rpm and stayed there.

KOEO: 11 | 41
KOER: 23 41 13 73

13
(O) ISC did not respond properly (extends to touch throttle then retracts for KOEO) - ISC
(R) Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too high)
(M) ISC sticking, open ITS circuit or TP sticking


23
Throttle sensor out of range or throttle set too high - TPS


41
(R) System lean - Fuel control

(M) System was lean for 15 seconds or more (no HO2S switching) - Fuel control


73
(O) Rerun test, if 73 is still output replace TPS

(R) No Throttle Position Sensor (TPS) change in "goose" test Must get at least 25% throttle rotation - TPS

i did the KOER test 3 times. 73 stayed each time. and i revved from an idle(1200 rpm to 3200 rpm) for the goose



IAT is new as of last night
TPS new 3/2011
ECT new 5/2010
ECT(gauge cluster) new 5/2010
MAFS junkyard from a 94 12/11
IAC new 5/2011

CPS, FPR, oil level/pressure are all the same since i bought the truck. the new tps was also tested when i got it. i remember it came to .1 over the 'perfect' voltage. 0.97V i think?

 

[Xeek]

Could be true.maybe you messed up the senor with the efan.

you know what. maybe. its not throwing any ECT codes tho

for anyone that doesnt know, i have my spal fan controllers temp sensor wire tapped into the signal wire on the ECT harness. fan works properly according to the engine temps

 

[jd4242]

Maybe you just have a bad ecm.

 

[Xeek]

i almost bet its the wire harness if its not a sensor. if it is the wires/computer im just gonna leave it alone until i pull the tranny and engine.
but if its not, i want it fixed now.