ported ej22t maf

[legsportwag]

Any one ever done this? Got bored with the lathe and did this.. Thoughts?

[legsportwag]

This is the extra maf FYI. Haven't installed it yet

[mike-tracy]

On a turbo? The stock ecu is tuned for the stock piece, and im not sure it would make a difference. But i could be wrong.. Crank up the boost a psi or two and feel a real gain.

[legsportwag]

Its actually to help clean up turbulent air passing through the maf. Most everyone pulls the factory screen out to help improve air flow, yet leaves ridges in the path.. I'm willing to bet this will only help clean up fuel delivery and help steady afr's.. I may try this before the 20g ecu n green jecs.

[mike-tracy]

I think you'll find most people leave the screen in for safety. Regardless it is an interesting angle to test out.

[legsportwag]

I guess the screen deal comes from my euro love lol, vw guys port there mafs, throttle bodys, and remove screens all day long lol

[kimokalihi]

The maf is something I'd never mess with. Its designed with the geometry calculated into the ecu. If you're attempting to smooth it out that might help very mildy but its not worth the risk of messing with the readings. If you're actually porting the whole thing wider you will certainly mess with the readings. It'll flow more air than the sensor thinks and therefore run lean.

[legsportwag]

I've always pulled my screens. Bosch LH-jetronic (hot wire maf, Volvo and Porsche) has been fooled personally with 565cc injectors on a stock tune simply by messing with the maf.. Dyno showed 200whp, 250wftlb on a 2.3l 8v sohc Volvo turbo (760 motor in a 245).

Anyways vw guys do this kinda stuff all the time to aliviate stumbles and help stabilize the ecu by simply stabilizing the air as it passes through the maf. Pic shows clearly that the plane of the tip of the sensor orifice has remained unchanged in the body of the sensor housing. Thus in theory the actual capacity of the maf sensor itself has remained unchanged..

The rob tune ecu won't be here till Thursday. Thus I'm going to toss this ported stock maf in my personal 91ss and see how it does for the next few days. I'll keep a close eye on afr's and pay close attention to behavior. We'll see how it does

[wtdash]

Thought I'd share Rob's take on this.

I sent him THIS POST on RS25.com. This is similar to what Doug Vincent/RedDevil did to the JECS/AUTECS MAFs.

His response:

thanks for the info. Unfortunately the majority of that information is crap. The step in the housing has nothing to do with the limit of the MAF. It is 100% a function of the the electronics inside the MAF. The Z32 MAF is the same size as the ej20g MAF, but it can measure almost 2x.

Don't shoot/shank/flame the messenger.

TD

[legsportwag]

Why not take advantage of the larger maf? SVX blue jecs maf is same as Nissan (sensor body shape, no internal step). I've been considering calculating the % of the larger surface area of the larger maf and calculating injectors via same percentage.. Bring duty cycle down with bigger injectors gets same affect..

Let's say svx maf is 15% bigger (Moves 15% less air over the actual sensor within the maf)
So with a 550cc tune (525) 15% of 550 is 86.5cc. So add that 86.5 to 550 gets 632.5cc injectors. (15% bigger)
(Less air moving over the sensor means it won't peak out as quick)

I really hope Rob tunes in

[legsportwag]

Also found this.. Is reddevil here as well?

http://forums.nasioc.com/forums/showthr ... ?t=1822687

[legsportwag]

http://forums.nasioc.com/forums/showthr ... ?t=2167401

[mike-tracy]

in the second link Marnix says that the aa160 maf (also the same one 92+ N/A legacys use, and the one required for a robtune) flows (measures?) more stock than svx (which can measure more than the aluminum SS one).

[legsportwag]

Yea he is thinking backwards. It measures more air, but only by directing more air over the sensor (peaks out sooner)

The theory is bigger (housing only) mafs move LESS air over the sensor thus telling the ecu LESS fuel. Thus one needs to compensate for the lack of fuel with ether bigger injectors or higher fuel psi. This combination simply is to bring injector duty cycle down (%) giving the ecu more head room when the maf is at full demand.

[legsportwag]

Also just as an FYI the ported aluminum maf has helped my random idle stumble, as well as tightened up the Afr sweep during driving conditions. I'd call cleaning up the maf machining a success

[Legacy777]

What are you using the measure AFR's?

Can you elaborate what you mean by "tightened up the afr sweep..."


Regarding using a larger MAF sensor body with bigger injectors to fool the ECU, it's not that simple. First, the MAF sensor response curve is non-linear, so you cannot simply assume 15% larger MAF will work with 15% larger injectors. Take a look at this graph of the two Legacy MAF response curves.

http://www.main.experiencetherave.com/s ... ansfer.xls

Second reason a larger body MAF with larger injectors won't fool the ECU is because different injectors have different latency times, and unless you can update the injector latency values in the ECU the ECU will not be properly utilizing the injectors.

[legsportwag]

I have an innovate lc1 wideband.. Any ways Afr sweep means how much your afr's bounce around at any given condition. My afr's at idle have always bounced between 14.2-14.9. With ported maf I see the wide band bounce around a lot less. Sticks much closer to the target 14.7 mark. Just at idle. Same is true at cruising speeds.. Also the car cleans up much quicker under load..

I'm simply playing with stock ecu while its still installed.. Porting the maf has helped lean out the tune very mildly. My dohc 2.2 w/ td06 20g and a massive fmic seem to like the more stable maf..

Next on my porting list is a throttle body. See if I can clean and open up the entry way a bit

[legsportwag]

Awesome info Josh! Just the kinda stuff I'm lookin for