Post-Intercooler MAF

[Andy_Mac]

So has anybody gone down this route or just have any experience with it.

The tuner I'm using is having some trouble getting the tune sorted because in low load/ low rev scenarios the air is taking too long to get to the engine so the MAF scaling corrections are constantly jumping around as the ECU is thinking the air is being lost but really it just hasn't got the the engine yet.

Have heard of a few Aussie guys doing it on blended tunes where the MAF's used to a point and then switches to speed density but never it needing to be done at such mild power levels.

Only downside I can think of is losing ambient air temp boost corrections which with a decent sized intercooler shouldn't matter much i'd imagine.

[knockoutgiant]

In for information.

Post-intercooler MAF dosen't sound like a bad idea at all...

[Guest]

Sure i mentioned it to both you pricks its a bloody good idea. Gives more headroom for maf too. Stm dont like it from what ive heard. Everyone hates anything that isnt common over here. Surely someone has sorted a sd reflash for legys by now? Ambient doesnt matter f all compared to post intercooler iat and moving maf gives you that.

[Andy_Mac]

Haha probably. Were you thinking straight MAF relocation or going for a blended/full SD setup?

Yea Aussie Matt has done atleast one blended tune on a stock ECU that i've heard of, think its a ****load of work with all the additional coding but having done one already i'd say most of the hard work is already done. Straight MAF relocation is surely just a matter of knowing the pipes internal area and how even the flow is through it and then scaling tweaks can be done during the tune.

[Guest]

Jump on nasioc see how those lads do it.

[Kiwi_Fozze]

Fairly sure theres a sd reflash available, but the extra tuning is unbelievable.

Enables you to fuel directly from map sensor, maf is retained to gauge air temp or you can piggyback the loom to an air temp drill in sensor post ic

[Andy_Mac]

Had a look. Seems semi common over there. Not too many downsides other than blow-by contaminating it. May have to upsize the intercooler piping where the MAF would be though. Not sure what kind of airflow max's out the Legacy ones but the stock tube in the airbox is 2.75 and my cold side is 2.5 so it'll straight away see more airflow than it would with the stock airbox.

[Guest]

Whats stock tb size? Could always plumb breathers to a can.

[Andy_Mac]

2.75" IIRC.

Yea should really do a catch can setup anyway. Sounds like the manifold connection to the PCV needs to be capped off too, which seems to be a stumbling point for most getting things right.

[lachlan]

Ive seen it done a few times on skylines in oz . Usually it was placed not far after the cold end of intercooler .

[Marky]

Real common to do in lancers too

To be fair it seems weird your car is having such issues, when every other subaru with a FMIC you never really hear about it (at least, not to the point of it being a problem worth solving)

[Andy_Mac]

Yea its weird ay. Chucking the top mount in temporarily this week to do some logs to confirm it is the extended pipework causing the issue.

How many people actually look into their low load fuel trim results though. Sure alot out there just think since its sweet on boost its sweet everywhere else. You wouldn't know there's any issue driving it but the ECU just keeps swinging the fuel trims all over the place. Think the tuner was only finding it problematic with it going rich on initial acceleration which could be part of the issue with its slow spool up.

Did you ever spend much time looking into those values on yours Marky?

[Kiwi_Fozze]

Worth having a look at your tip in enrichment too to possibly pull out some fueling

[Andy_Mac]

Say I grabbed something like that at 3", any idea how even the airflow would actually be if mated to 2.5"-3" silicone adaptors at each end. Silicone adaptors have a fairly short diameter change so thinking it might not give the best readings, even with the air straightener.

http://www.treadstoneperformance.com/product.phtml?p=68092&prodname=DENSO+MAF%2C+Mass+Air+Meter+Pipe%2C+Subaru%2C+Scion%2C+Mazda%2C+Toyota%2C+Lexus

Or there

http://www.kstech.biz/blow-thru-maf-2/

Edited April 5, 2016 by Andy_Mac

[Andy_Mac]

Expanding on this slightly. Think this weld on option will work out better as the silicone couplings will just make the whole thing even wider and harder to fit than it already is between the battery terminal and oil fill tube. Thought about making one but haven't yet found anyone who can supply the reducer sections.

http://www.kstech.biz/megamaf-weld-on-blow-thru-maf-housing-aluminum/

Based on the info on there I think the 77.5mm(3") option may be the way to go. Their power calcs (probably conjured out of thin air) show it maxxing out the MAF at about 340wkw.

Or drop down to the 73mm (2.87") option which allows about 310wkw which may make fitment slightly easier, and allows a smaller diameter transition to the 2.5" current pipework, which may help consistancy aswell.

They rate a straight 2.5" pipe at 240wkw which doesn't leave alot of headroom for future modifications so pretty confident upsizing at the MAF is the best way.

Thats my plan at this point anyway..

[Guest]

Where are we at with this andy?

[Andy_Mac]

Nowhere. Dave reckoned it was a crock of **** that a post intercooler MAF was the best way and that it shouldn't be an issue at my power level for him to tune out the issue. Tune at DTech is this friday so should know for sure after then. Looking damn forward to seeing how fast it spools with a real tune on it and not the ****ty lag loving current one

[Guest]

So good idea just wont fix your problem?

[Andy_Mac]

Good idea, would definately work but he seemed to think it'd be easy enough to tune out and not worth the trouble setting it up. Would need a proper catch can setup to go with it I think.

Edited June 28, 2016 by Andy_Mac

[Kiwi_Fozze]

Dtech are getting themselves a reputation

And my God is it a good one, wonder if he's noticed a big increase in demand. Probably the best pro tune outfit in the north island atm...