I've been looking into this for the past few days now, and I can not find anywhere an explantion as to why you would want to do it.

I've got an Apexi Power FC at the moment so I know unless I can find that deleted attachment Apexi did, I'm gonna have to change to another system such as Simtek.

But still, whats the point of this mod, other than it means you won't have to replace it whwn it fails

I'm preparing for a 400bhp conversation, and its mods like these people keep meaning to me. But as I've normal hung around the 330bhp mark, I've never looked into this sort of mod, so forgive my ignorance.

 

the faster the airflow the more likley the MAF is to fail, as i understand it other than risk of failure at lower power theres not much difference, higher the power band they dont work correctly due to not being acurate enough, i may be wrong on that but thats as i understand it.

i've gone mafless because mine shat it out during mapping with a bigger turbo and front mount, i went down the autronics route

 

your better off with the maf gone as most induction kits cause the maf sensor to fail so when its remapped with for example a simtek ecu you can cancel the maf so you can work away with an induction kit and dont have to worry about the maf going

 

Went through 3 MAF's in a few months on my my99, the simple fact is (as stated above) they are sh1te and cannot cope with the higher airflow and the induction kits. They even fail regularly on non modded cars as well.

I had a new MAF from Subaru go faulty within a WEEK!! Cost me £95 as well!!

I now have a Haltech aftermarket ECU and no MAF and things are great!!

 

slightly duff information above but hey ho thats what you get nowadays.

MAF is an excellent way to control the fuelling, the problem came about with the 99 cars that changed the sensor type to a bubble between 2 plates irrc.
As the pressure increases or decreases the pressure on the plates does the same and the bubble increases or decreases in sectional area.
Early mafs are great and seldom go wrong, later mafs are also great but cost a bleedin fortune.
The early uk/wrx maf isnt that great because the tubing is quite restricted so uprating to an sti is a good move.
There are also other options like blow through and nismo mafs.

People here heard a rumour, added their tuppence and came up with a theory.

MAF = good.
99 maf = fragile, however subaru attended to this with the "green spot".
newage = good.
As for running out of measurement? Well maf can be rescaled on much of the aftermarket ecus and software so thats not strictly true either.

 

The above is true but doesn't mention one of the main reasons for ditching the maf, smoothness.

The maf will only read up to a certain amount of airflow before you need to rescale in into a larger diameter housing. The thing is it can't sense a difference between air going into the engine whist on boost and air trying to find it's way out of the engine when you lift off i.e. compressor stall. It see's the air leaving the engine, thinks it's going in and adds in more fuel. All of which results in a jerky on/off throttle response.

The mafsim route is available to apexi users, I ran one for a few years. They had some reliability issues but if you get a good one they seem to be ok.

 

you can bypass air with good results Colin.
Basically using the take offs on the inlet you can have more air running than the tube diameter and as it can be mapped for like that.
Maf voltage remains good.

How's that 2.33 going?
One of my biggest regrets is not striking sooner and then when I did get it ready there were no bloody blocks left

 

I'm with Peanuts here.

A MAF weighs the air perfectly. Didn't realise the V5&V6 ones had a bubble in. I've never cut mine open, I was under the impression they switched to a hot film type which once contaminated just burns up. The earlier ones I thought were hot wire type which can be cleaned.

Without a MAF you normally head to a speed density system which uses the MAP sensor and a temperature sensor to work out the amount/weight? of air.

My tuppence

H

 

Interesting. I had the my99 style and never rescaled, just went with the mafsim for simplicity

I have experienced a 400/400 sti2 that was rescaled and that was a jerky as anything, he runs mafsim now.

As for the 2.33, you probably don't want to know. It's bloody great. Just got it mapped last week with a gt3040r and fooken ell it's got big *****. It's got a 4k powerband with standard heads.

Might have a link to some more box fresh ones, just waiting on a reply to an e-mail.

 

You could very well be right now I think about it, the point being that its not a hotwire version like early cars.
I have one at home and I'll butcher it open tonight.

Colin, I'm glad to hear its going well, in the end I plumped for a forged 2.5 with a 321T so I'm reasonably happy

The jerkyness is a red herring I reckon, injector lag times not correct may give that symptom

 

Jerkyness on off throttle is caused by MAF , VTA dump valve and front mount combo generally speaking...
Doesn't happen anything like as much with recirc dump valves..

Having fitted many SimTeks in direct replacement for Apexis in some circumstances , all of my customers have reported that their car is smoother on the map based system...

 

Jerkyness isn't a red herring, it comes through large volume of pressurised air in the FMIC all trying to go through a relatively small diameter pipe vis the DV upon a closed (and worst case patially closed) throttle, result is the air being forced back past the turbo and through the MAF, hence the MAF reading high when airflow through it should be less. This results in the jerkyness.

It isn't the MAFs fault, just inlet pipework / DV management, but the jerkiness is often seen on the popular large turbo / FMIC / MAF setups. Basically the DV can't get rid of (or recirc) the volume of air quick enough, the excess gets pushed back past the MAF and gives unwanted readings.

Going mafless ot blowthrough solves this.

But yoou know that anyway Andy

 

OOps I was writing my reply during your post Martin

 

Happens when you delete the dump valve, you can drive around it, but it is a bit annoying on occasion though! I do love the "Squirrel blender" sound though

 

I'm no expert on this matter but shouldn't it be pointed out the most salient thing re MAFs... Namely that if the sensing wire/film gets contaminated it's possible for it to fool the ECU into underfuelling (ECU thinks the engine's getting less air than in actuality).... And serious detonation can set in (more so on the 99/00 ones).

I thought this was the main reason why it's attractive to go MAFless - gives colossal peace of mind and all that...