Can the MAF-with-built-in-IAT issue on 2000 5.0L MM be clarified please?

[rigbyrigz]

For my 5.0L 2000 Mercury Mountaineer at 200K miles, I got 10 years ago, I am greatly in need of authoritative word on the MAF and IAT issue. That being, is the IAT on this model (year) 100%-always-part-of -->built-in to the MAF?

I'm not mechanical, but I have driveway helpers. Basically, rough driving and frequent P0171 and P0174 codes influenced me to get another MAF - $25 (new, just the sensor no housing or assembly) that matched the pn spec and what the current one looks like - and have them replace it. Checked for air leaks, tears, loose, etc. of course first. Replacement (with proper unscrew bits) went smoothly.

At first the P0171 and P0174 codes went away (several trips and miles of course for historical fuel trim numbers to make them reappear if "pending") and seemed a bit improved, but soon a P0112 (IAT or related wiring) popped up. Checked for loose wire harness and other things, and actually went so far as to order the Fitting IAT part (specc'ed) from Advance.

(Then) On the way to town, it held back at 20mph when I accelerated for a bit, but then freed up. Some normal driving then but twice at 50 as I was giving it gas it instead dropped to 40. When I started it after a stop, it sputtered, and after a few feet, seemed to lurch and stall, so I stopped. After some rest, it actually bucked and sat there shaking upon starting. However, after I disconnected the MAF it was then OK. Sent that new MAF back to the retailer, and re-installed the old one. So, I am back to somewhat rough driving at times and frequent P0171 and P0174. (note: last year replaced O2 sensor and fuel filter, sea-foamed, etc.)

While thinking about the MAF issue, I looked for the installed IAT, and "we/none of US" could find it (on intake tube or near manifold, or anywhere.) I won't mention that the genuine FITTING IAT Intake-Air-Temperature-sensor part I finally ordered from Advance (1 of 2 - the other is a Manifold Intake Air Sensor) has an etched part number on it that corresponds to "MAP - Manifold Air Pressure" sensors. I also won't mention that the ECT Engine Coolant Temperature Sensor (sender?) is often called IAT in the gads of write-ups online I saw while looking at forums and diagrams.

Neighbor "experts" that said "nahh it aint IN the MAF" (when I suggested THAT) were perplexed they found no place FOR the IAT (i bought) or located the (old/current) IAT itself. Lotsa other stuff (senders/sensors) of course seemed possible (as IAT) but "Nahh" on all we checked. (AND) The current(old) MAF seems to have a little window-opening with a fuse-like prong that some say: yeah that must be the built-in IAT (different than the sensor piece of course, to the outside right.) Maybe yes?

Not sure if the returned MAF (after the bucking/stall) had that same window&prong, I think yes. I NOW wanna buy another MAF, to spec, and under $30 if feasible. Ford genuine and name brands get ya up to $300 or so. But no one seems to say OEM and third-party MAFs tend to be crap. I want the right one for my vehicle (in its current state) of course. (I’m thinking remanufd. isn’t a great path.)

Yeah, if there is an IAT problem and IF there is a separate IAT connection location we can find, and find the right sensor to install, I want to do that as well, eventually. But I'm insanely perplexed as to if any MAF to spec I buy ($30 or $300) will (always?) have the IAT built-in for my 2000 5.0L MM model? If yes, of course I don't need(want?) another separate IAT. If no, how do I buy the right MAF and figure this all out without more migraines? THANKS!

 

[imp]

For my 5.0L 2000 Mercury Mountaineer at 200K miles, I got 10 years ago, I am greatly in need of authoritative word on the MAF and IAT issue. That being, is the IAT on this model (year) 100%-always-part-of -->built-in to the MAF?

I'm not mechanical, but I have driveway helpers. Basically, rough driving and frequent P0171 and P0174 codes influenced me to get another MAF - $25 (new, just the sensor no housing or assembly) that matched the pn spec and what the current one looks like - and have them replace it. Checked for air leaks, tears, loose, etc. of course first. Replacement (with proper unscrew bits) went smoothly.

At first the P0171 and P0174 codes went away (several trips and miles of course for historical fuel trim numbers to make them reappear if "pending") and seemed a bit improved, but soon a P0112 (IAT or related wiring) popped up. Checked for loose wire harness and other things, and actually went so far as to order the Fitting IAT part (specc'ed) from Advance.

(Then) On the way to town, it held back at 20mph when I accelerated for a bit, but then freed up. Some normal driving then but twice at 50 as I was giving it gas it instead dropped to 40. When I started it after a stop, it sputtered, and after a few feet, seemed to lurch and stall, so I stopped. After some rest, it actually bucked and sat there shaking upon starting. However, after I disconnected the MAF it was then OK. Sent that new MAF back to the retailer, and re-installed the old one. So, I am back to somewhat rough driving at times and frequent P0171 and P0174. (note: last year replaced O2 sensor and fuel filter, sea-foamed, etc.)

While thinking about the MAF issue, I looked for the installed IAT, and "we/none of US" could find it (on intake tube or near manifold, or anywhere.) I won't mention that the genuine FITTING IAT Intake-Air-Temperature-sensor part I finally ordered from Advance (1 of 2 - the other is a Manifold Intake Air Sensor) has an etched part number on it that corresponds to "MAP - Manifold Air Pressure" sensors. I also won't mention that the ECT Engine Coolant Temperature Sensor (sender?) is often called IAT in the gads of write-ups online I saw while looking at forums and diagrams.

Neighbor "experts" that said "nahh it aint IN the MAF" (when I suggested THAT) were perplexed they found no place FOR the IAT (i bought) or located the (old/current) IAT itself. Lotsa other stuff (senders/sensors) of course seemed possible (as IAT) but "Nahh" on all we checked. (AND) The current(old) MAF seems to have a little window-opening with a fuse-like prong that some say: yeah that must be the built-in IAT (different than the sensor piece of course, to the outside right.) Maybe yes?

Not sure if the returned MAF (after the bucking/stall) had that same window&prong, I think yes. I NOW wanna buy another MAF, to spec, and under $30 if feasible. Ford genuine and name brands get ya up to $300 or so. But no one seems to say OEM and third-party MAFs tend to be crap. I want the right one for my vehicle (in its current state) of course. (I’m thinking remanufd. isn’t a great path.)

Yeah, if there is an IAT problem and IF there is a separate IAT connection location we can find, and find the right sensor to install, I want to do that as well, eventually. But I'm insanely perplexed as to if any MAF to spec I buy ($30 or $300) will (always?) have the IAT built-in for my 2000 5.0L MM model? If yes, of course I don't need(want?) another separate IAT. If no, how do I buy the right MAF and figure this all out without more migraines? THANKS!

Easily solved quandary. BOTH MAF and IAT sensors are mounted in the inlet air duct, sometimes right next to one-another, before the airflow enters the throttle body, sometimes COMBINED into one small module having only one electrical connector instead of two. Here are the separate units:

Above, typical IAT disconnected. When combined with MAF, two additional wire leads are used in the MAF connector.

 

[rigbyrigz]

Thank you very much for reply... hope you will entertain a follow-up clarification request.

My current (and aged) MAF has six wires (which reading leads me to believe it therefore has the integrated IAT). The connector (plug?) for it also has six holes, so I guess the vehicle is "expecting" the MAF-w/IAT...

(...and there is no (separate) IAT in view, disconnected, a spot for it, or otherwise)

But apparently, some 2000 MM 5.0L do(???)have a separate(d) IAT as in your second photo. This implies that the MAF on THOSE said vehicles, if that IAT is connected and active, should be NO-integrated-IAT, or 4-wired, or whatever makes sense (for an MAF on such a vehicle...)

...but when you order or buy a FITTING-2000MM5.0LV8 MAF, using original manufacturer part numbers or reliable OEM replacements, there does not seem to be:
XYZ-AA: for vehicles needing an MAF WITH integrated 6-wire IAT ---or---
ABC-AA: for vehicles needing an MAF withOUT IAT (because it is separate )

So, my purchase wasn't a choice of 2 pn's, but just what brand what condition what price for the single part number...

...could the retailer have sent me an MAF withOUT IAT (when my vehicle needed one) -> hence the P0171 P0174 codes went away, but an IAT code (P0112) then popped up first time... and eventually all hell broke loose, as in my post?

Do you see my continued quandary? You said it would be easy to ascertain, and I'm not finding it easy at all, and feel very dumb, and sorry to bother you for hand-holding follow-up, but thanks to you (and all others who may be reading).

 

[fastpakr]

Do you see a part number on your current MAF?

 

[rigbyrigz]

Thanks I do see a partnumber on my current MAF (with several other numbers that google to confusing or strange results) and other than the 4 digit prefix for Genuine-Ford I did an exact match... even to the AA as suffix, not Ab or other....

...but here's the glitch I think. They sell FITTING MAF (with THAT part nbr for my 2000 MM V8) but they also say FITS 2005 focus, 2003 mustang, etc. The great guy rocket5979 here said many times these guys using OTHER model MAF to better their fuel mileage are playing with fire because the MAF is very sensitive AND is CALIBRATED to the make and model.

in fact the 46 minute you tube i watched the read was 7.8 so he THEN got a genuine Ford MAF that read 9.1 and sure enough the fuel trims went from 20 and 40 to 1 & 2 and he was good (along with fixing an air leak to brake booster.)

So even if i get 6-wire WITH IAT don't i need to worry about that? getting a $30 MAF from anyone no way i think to know it's calibrated for my 2000 MM V8 if that is as important as some think. Heh.

 

[rigbyrigz]

oh yeah just to fully answer, there is (also) a white paper stickon label on the current (old) MAF but worn thru so can't read anything on it. yeah its pretty obvious im trying to get a better MAF match next try (as the first replacement was near-disaster) but still be economical (efficient, effective? lol.)

and of course the previous owner 10 years ago may have replaced the original MAF with one not exactly perfect (calibrated or whatever) yet it lasted for 10 years. so these numbers on the current one have the distinction of that possible glitch. sigh.

 

[rigbyrigz]

I get the impression from articles such as How to Calibrate MAF Sensor (What is The Mass Air Flow Sensor ) and other literature, that when you clean and install (or replace new) an MAF sensor, and disconnect and reconnect the battery, it will clear out (of the computer) the historic fuel trim settings. Then the vehicle will relearn the operating conditions... and a functional MAF will do it's job...

...it seems this is also a form of calibrating, and perhaps it doesn't matter that you get a CALIBRATED MAF to spec when you buy and install a replacement. Sound right to any expert reading? So just the PN and a reliable retailer may be enough here (still not sure if AB is as good as AA as a suffix, just a later version, like on F150 part numbers...

It was also fun to learn (in a way) why a car may run (at all, or better) if you unplug the MAF when having issues. The computer will guess at the best air-fuel (trim) ratios, and while not a good long-term idea, this in the interim could be a vast improvement. heh.

 

[rigbyrigz]

Hate to be annoying, but discussed this all with my local yokel helpers (affectionate term) they never heard of explicitly Calibrating an MAF. Yet rocket5979 and others seem to point at that as a potential pitfall...

...some of have heard of calibrating an IDLE where you have to disconnect certain things in order. But just disconnecting the battery node 10 minutes or something (as they did) is supposed to clear the computer and be a reset, and I guess that would wipe out historical (detrimental) fuel trim data...

...yet I see many retailers talk about calibrated MAF for sale. But its not like they ask your make model and engine so that they can do the calibration on some expensive machine there, before sending it. What am I missing (if anything?)

upd: so some are saying get the scan tool that let's you do tuning (I am old enuff to remember bringing car in for a pricey tune-up regularly!!)
some are saying just live with the codes (p0171 p0174)
some are saying do an ECU ReLearn (but how, other than idling and driving and rinse and repeat)
im starting to think just darn getting another $30 MAF - with 6 wires (IAT) of course - resetting battery - and taking on other life challenges may be best for me, lol (subject to further guidance here of course)

 

[C420sailor]

You shouldn’t need anything fancy. Calibrated MAF sounds like a sham—truck should run fine with normal parts.

If you have live data (you just if you can see trims), what is IAT reading?

 

[rigbyrigz]

You shouldn’t need anything fancy. Calibrated MAF sounds like a sham—truck should run fine with normal parts.

If you have live data (you just if you can see trims), what is IAT reading?

Thanks! Unfortunately my nephew, a Ford mechanic, is in Jail, and some folks around here stole his scan tool and tools. I bought a cheap code reader that reads the check engine codes, and allows resets/erase, and that's all, no Live Data

Again, due to slightly rough driving, acceleration, idling, and frequent P0174 and P0171 codes, after fuel filter, O2 sensor, cleaning, checking... I finally decided try a new oem fitting MAF. Seemed OK at first, but then IAT codes (P0112 popped up). I actually bought an IAT to spec at Advanced then, before I realized I didn't have a separate IAT but it was built in to MAF...

...on the way to town to get the IAT, after a few previous trips of no drama, the crazy misbehaving started on accelerating, and finally it would start but only buck and shudder. Disconnected the MAF it was OK> Put old MAF back in, still OK (thought still a bit rough and still getting P0171 and P0174.

Do I need a fancy scanner tool and get some trim and temp data? or- Do I just buy another fitting MAF, reset battery, try again, and not worry about ECU relearning, tuning, calibration, etc? I think the answer is yes, but open to further guidance and insights ----and thanks.

 

[C420sailor]

I would check for continuity between the ECU connector and the MAF/IAT connector pins. Rule out wiring.

If that checks out, shift attention back to the sensor. Someone on here a while back posted about how to determine whether a MAF sensor has the IAT built in. It was a visual difference in the part. Can’t remember.

 

[rigbyrigz]

I would check for continuity between the ECU connector and the MAF/IAT connector pins. Rule out wiring.

If that checks out, shift attention back to the sensor. Someone on here a while back posted about how to determine whether a MAF sensor has the IAT built in. It was a visual difference in the part. Can’t remember.

Thanks!
I'm thinking if the MAF has 6-wires it means IAT built-in, but only 90% sure on that, in case someone has 100% agree.

 

[CDW6212R]

The MAF uses four wires, power, ground, reference and signal. The IAT uses two wires. Look at your air inlet hose between the MAF and the TB, the IAT is in the side of that.

 

[rigbyrigz]

The MAF uses four wires, power, ground, reference and signal. The IAT uses two wires. Look at your air inlet hose between the MAF and the TB, the IAT is in the side of that.

THANKS! Here's my MAF and surroundings; a friend car expert of sorts said he doesn't see where the IAT is to be expected so probably yeah it's IN the MAF, which in my case has six wires and a 6wire connector. For 2000 MM 5.0L V8 it's XF2F-12B579-AA.... others have said Nahh it ain't IN the MAF but seems it is... so I am back as to which one to Buy... oh instead of P0171 P0174 today I got P0156 = o2 sensor (replaced LAST year) hope the MAF default ECU running hasn't damaged anything, been at this several weeks (driving)as I try to solve this MAF (IAT) issue.

 

[CDW6212R]

Someone else should post in here who owns another 2000 302 Explorer to say for sure. The confusion seems to be that Ford moved the IAT to the MAF, which on yours the connector has six wires. You did the right thing by asking, the parts books have errors at various times, it's very complicated the number of parts, and changes that happen regularly. So parts sources of information often conflict.

So you have a six wire MAF connector, then it needs the matching six wired MAF, which will have the IAT as part of it.

 

[CDW6212R]

For the lean condition code, what is the fuel pressure, as the last time it was checked? That could be the pump, or fuel filter, less likely a vacuum line cracked etc. But check the fuel pressure soon, be sure it's above 55psi at least, preferably 60psi or more.

 

[rigbyrigz]

For the lean condition code, what is the fuel pressure, as the last time it was checked? That could be the pump, or fuel filter, less likely a vacuum line cracked etc. But check the fuel pressure soon, be sure it's above 55psi at least, preferably 60psi or more.

THANKS
I don't have live data. i asked Matt at OBSoftware about a purchase of their app, and the OBD2 tool on Amazon called FOSEAL Improved Vrsion Car Wifi OBD2... looks like a GO, so maybe i will have data later in week... for now using a cheap code reader can read and reset thats all.

Hello,
We do have an enhanced package for your vehicle that's available for $10 in OBD Fusion. For most vehicles, fuel trim data is available over OBD2. However, the enhanced package provides access to a number of additional modules and sensors.
Thanks,
Matt

 

[CDW6212R]

Unless some other issues may exist to affect the A/F ratio(prior electrical issues etc), I'd quickly go rent a fuel pressure testing kit from any parts store, and check it. Auto Zone etc, they all rent that tool, you pay for it, use it for a day or two, and bring it back for a refund. It's easy to use, takes about five minutes to hook it up and turn on the key. Your fuel pressure should be the same under all conditions, idling, WOT, and with the engine off, just the key turned on.

 

[jr230]

Unless some other issues may exist to affect the A/F ratio(prior electrical issues etc), I'd quickly go rent a fuel pressure testing kit from any parts store, and check it. Auto Zone etc, they all rent that tool, you pay for it, use it for a day or two, and bring it back for a refund. It's easy to use, takes about five minutes to hook it up and turn on the key. Your fuel pressure should be the same under all conditions, idling, WOT, and with the engine off, just the key turned on.

have them also run the codes they have better scan tools and it is free

 

[rigbyrigz]

my nephew the Ford mechanic in jail still but through a third party been trying to exchange info about my vehicle which he worked on a lot (replaced o2 sensor last year when i coded... sadly maybe i let the default ECU trims go too long because all of a sudden i got a P0156 o2 sensor code yesterday first time in a year... been getting frequent p0171 and p0174 and yeah i understand they are pending and may take 2-3 trips or 50 miles to pop up, and i may have a better scanner tool by weeks end with live data even) anyway i asked him if i have a schrader valve...

seems all pre-2004 GM have it but not sure of Ford. saw 2-3 nicely reviewed fuel pressure testers for sale amazon/ebay for about $30 i can afford but seems to need a schader valve doubt my local yokel driveway mechanics can handle the adapters or other workarounds if needed if doesnt.

maybe more a curiosity: i ordered the six-wire MAF
NEW - OUT OF BOX - OEM Ford XF2F-12B579-AA Mass Air Flow MAF Sen...
$24.95 eBay.seems worth a shot and good PN anyway for me and good price

but my prior try to replace the MAF... which ended badly with the lurching, shuddering, stalling that resolved when the new MAF was in a few days... (but)i believe successfully reLearned ECU which i think means will suffice for Calibration, after 10 minutes left battery diode and all that done to do a reset and clear the trim numbers and other data...

...but the curiousity was that before that happened and the p0171 and p0174 seemed to disappear (may have been pending but didnt have tools to know that) i got a P0112 code - IAT (or wiring). that hasnt happened since im back to the old MAF (just getting intermittent p0171 p0174 UNTIL YESTERDAY's p0156) ...but how does an IAT (p0112) code work with an IAT BUILT-IN to the MAF. the usual remedy for p0112 is check the wiring/ REPLACE the IAT... but of course i dont have an IAT i can replace. actually ordered a fitting one to spec but found no place to put it which is how all this Tale Began lol. Cheers. and Thanks for reading.