The difference between NA and TT MAFs

[scott.mohekey]

Today I had the MAF out of my new legnum to replace it with a spare, due to the previous owner fitting it with a 4" pod filter, resulting in the grill being completely removed from within the MAF. I'm guessing he was trying to increase air flow or something.

Once I had that out of the way, I decided to take the MAF I'd just removed from the car apart, and compare it with the innards of a NA MAF which I had lying around. I also intended to swap the internals over so I would have a spare VR4 MAF in good condition instead of an NA MAF in good condition.

What I found out is quite interesting...

If you look at the top left of the following two photos, you'll see that the only difference between the two, is what looks to be an atmospheric pressure sensor on the first one (the VR4 MAF). The first one also has two extra pins soldered on the connector (the top two, right next to the pressure sensor).

I'm assuming the ECU uses this to make adjustments based on the atmospheric pressure. I wonder if it makes any use of this for boost control?

[Adam.Findlay]

well that answers my question in me head of where evo scan pulls the atmospheric pressure from and why it registers a different temperature reading to the air conditioning system

[scott.mohekey]

The temperature you're talking about is measured by a sensor at the front of the car, behind the front bumper. It's near the stock recirc valve location.

[taylor]

The temperature you're talking about is measured by a sensor at the front of the car, behind the front bumper. It's near the stock recirc valve location.

So where does the ext temp on the climate control read from?

[bradc]

External temp for the air con is at the front next to the stock BOV.

[scott.mohekey]

Yeah, I got them mixed up. I'm not actually sure where the temp that evoscan reports is measured.

[taylor]

Must be in the maf?

[scott.mohekey]

Actually, now that you mention it, there is at least three sensors visible in the VR4 MAF.

[Adam.Findlay]

i know the air con sensor is by the BOV but the evo scan one must register from the maf

[cobraest]

can i use the 6a13 N/A airflow sensor in my biturbo 6a13TT? what are these airflow sensor differences? will it work?

[scott.mohekey]

I can't comment on whether it will work or not, but the MAF for the 6A13TT has a barometric pressure sensor in it that the NA one does not.

[cobraest]

my mitsu mechanic says that n/a has the baro sensor. okey, i did take the n/a air sensor and put it to my turbo legnum and it worked it idles, in evening i'll go for a testdrive. no fault codes in ecu.

[swinks]

The only difference is operating frequency scaling.

[cobraest]

and that means? maybe the emission could be bad? i go friday to check that but it drives well in and stock boost.

[swinks]

It means that ecu will make engine to run too lean or too rich in areas you don't want to happen.

[Davezj]

If you look at the original pictures, you can see the additional sensor and all the associated circuitry next to it and the what loocks like the Revision of the PCB changes from C to D see board number at the bottom of the PCB.
and the modification record label at the top of the board changes also. so you are comparing two completely different Board designs, alot can change from one revision to another. the rev C PCB seems to be older and does not have the additional sensor fitted.

[Miss_laatjuh]

sow , 3 jears after last post time to re-open .. as u can see in the wtb topic i drive for 6 years with a v6n/a maf on my vr2 ..after control marksanne find out (big surprise for both of us) that he also drive a vr4 engine with v6n/a maf !!! sow somebody can explane us something about the different scaling's of the 2 mafs ? i go for a vr4 maf ufcourse and mark also decides to go look for a vr4 maf also (excuses for my english but i think you guys understand everything)

[swinks]

sow , 3 jears after last post time to re-open .. as u can see in the wtb topic i drive for 6 years with a v6n/a maf on my vr2 ..after control marksanne find out (big surprise for both of us) that he also drive a vr4 engine with v6n/a maf !!! sow somebody can explane us something about the different scaling's of the 2 mafs ? i go for a vr4 maf ufcourse and mark also decides to go look for a vr4 maf also (excuses for my english but i think you guys understand everything)

All your answers here below. This article is about Evo's but all principles applies to your question:
https://www.revvolution.com/auto-for...ormation-p-354
http://www.club3g.com/forum/3g-eclip...our-maf-s.html

[Miss_laatjuh]

thanks a lot !!