Versions of the '96-'97 80 mm MAF

[GEN 3 SHO FAN]

Since I saw a beautiful '94 RM Mark VIII, I turned my attention to this car by curiosity.

Their 4.6L engine use a 80mm MAF too. But according to an enthousiam site, this engine used 3 differents MAF between 93 and 98... More precisely, there are 3 identicals MAF but they use different transfert fonction chart. If I compare 93-95 vs 96 MAF transfert fonction, the 96 will send a little bit less voltage for the same amount of air.

Correct me guys, but looking at these, my deduction is :
- olders will do richer ratio
- newer will do leaner ratio

It seems that we are able to modify by a little bit the air/ratio when replacing with a different part number 80mm MAF. (!?) Each are calibrated for their ECU.

https://mark8.site/mark-viii-featured-tech-and-schematics.html
(see "Mark VIII specific" section)

I put here some notes to see if part numbers could help understand.

Mark VIII :
- 93-95 : F3VF-12B579-AA
- 96 : F5OF-12B579-AA
- 97-98 : F8LZ-12B579-AA
(Also, according to cross numbers on Rockauto, 97-98 Mark can take the F5OF-12B579-A.)

SHO :
- 96-97 : F5OF-12B579-AA
- 98-99 : I'm not considering the plastic MAF here (F81F-12B579-BA / XL3F-12B579-BA)

F-150 (Triton engines) :
- 97-98 : F5OF-12B579-AA
I found this one on too :
-97-98 : F8LF-12B579-AA (presently on my SHO...humm, is my a/f ratio is good, too lean ?)

I tryed to compare with our tranfert chart on V8SHO site but the measurements were taken differently. If someone know more about that, I will be interested to learn.

https://forums.corral.net/threads/can-i-use-a-maf-from-a-lincoln-mark-8-on-my-fox-5-0.1195688/
https://www.corral.net/threads/used...nterchange-on-different-ford-vehicles.986360/
https://www.corral.net/threads/junkyard-horsepower-summary.1092402/

 

[SHOZ123]

All the MAF calibration would be in the PCM. Unless your car is not running the proper AF I do not see any advantage to a stock motor.

Do you know what your AF ratio is?

The MAF can be tuned to accommodate almost all exhaust changes by changing the table values.

 

[GEN 3 SHO FAN]

Thanks Paul.

I don't know if my A/F ratio is correct (I don't have the equipment for that sadly), but I have some misfires on idle that cannot find the cause and the engine seems to be a little bit more hot than factory (will climb at 2/3 rapidly on a stop light even at 73F).

But according to some internet sites (Mark and Mustang links up here), MAF with different part numbers can send different voltage (for the same volume of air). I put one found some years ago on a F-150 thinking is was the same part. Now, I'm wondering if this MAF could do tricky things on my engine...

 

[luigisho]

Yeah. I bet the calibration is not spot on. I think I've seen some transfer over and sorta work but you really have to have data tables and really performance of the current unit to be sure.

 

[SHOZ123]

Unless you can tune the tables MAF a resistor will do the trick on the IAT......

 

[GEN 3 SHO FAN]

Thanks guys.

I will not go on a complex way (tune). I took the MAF of the '96 Mark VIII in a nearby scrapyard (same part number) and I will put it on and watch if some changes occur.

 

[SHOZ123]

I fiddled around with a single exhaust once. Went 2.5" with a single muffler. When they installed it they used an 2" pipe to link the Y pipe and the rest. It cut the power like crazy, but was quicker off the line.

The place was 30 miles away and I had to suffer all the way home. I could change the MAF values to get back a lot of lost power though. I took it back and they went the full 2.5" and I had to change it again but got her dialed in. I would use load figures to see what my changes did in the real world.

 

[luigisho]

Have you thought about maybe grabbing a used oem SHO one? Might be cheaper

 

[GEN 3 SHO FAN]

Sorry, I made a mistake in my last post : "I will not go..."

The one I found cost me 30$ CA without shipping fee. Its a fair price for the exact same part. (I think I was very lucky to have a 1996 Mark VIII which still have his MAF on nearby...)

 

[SHOZ123]

I vaguely recall trying out one of the plastic Gen 3 MAFs, '99 I think. Wanted it for the smoother flow but could not get it to work well enough. Probably some other programming parameter not available at the time.

 

[GEN 3 SHO FAN]

Well...

I must tell that after some time rolling yesterday in city with the F5OF-12B579-AA (the good one for a 1996-97 SHO) there are some differences. Mostly :

-> less heat
-> a bit more power
-> less ramdom misfires

The heat gauge which stay between 1/2 and 3/4 and could climb rapidly (I heard often the fans kicking in) now stay between 1/3 and 1/2 and the fans kick in rarely even when the car is parked with the engine turning (79F).

The engine seems a bit more powerful (by let say 15-20%), before it has to reach 3500-4000 to offer a good accel and now he does the same around 2500-3000 (before the growl).

I'm not sure but the F8LF-12B579-AA offerts a leaner ratio causing more heat. It's confirming what it's said on the Mustang forums (some with 70mm want to try a 80mm) : differents MAF can send different voltage to ECU. These are designed to work with different injectors (biggers in this case). The interesting thing is the Intech 4.6L of 1996 used the same transfert fonction as our 3.4L.

On Mark VIII forum, we can clearly see that they doesn't send the same voltage :
93-95 MAF :


96 MAF :


In comparison (for the same amount of air), it's seems that the 96 is sending more voltage at low rpms but less at mid rpms (by very small margins). They become almost the same for higher rpms.



I don't have the curve for the F-150 one sadly but the curve is probably more different. I'm sorry if I misled some with this F-150 MAF. The 2 are identicals in appearance except it doesn't have the same part number. I also remarked during replacement the mention "Japan" on the good one...

However the F-150 one could be useful for some heavy modifications (bigger injectors, , tunes, SC or maybe NOS). Hope some SHO source guys are reading this.

I'm glad that the heat problem seems resolved.

 

[gamefanatic]

Thanks for the info. My MAF has been giving me problems. It randomly gets stuck as far as the computer is concerned. I haven't diagnosed the wiring yet, but the only thing that seems to resolve the issue is pulling the battery. I ordered a replacement MAF. Hoping its plug-n-race, but when is it ever that easy? Being that pulling the battery helps vs unplugging it, I am expecting replacing it not to fix it...