when do you MAF's max out if they do...? is the Z32 TT maf a straight bolt-up mod?

I still wonder if all this talk about our MAF's maxing out is true or not...I think hlh was running a stock maf and so is mardi and sx7r...

 

The A32 maf is good for 350 hp, so a 5-speed putting down about 290 hp to the wheels is maxing out the maf. So how do Hal and Matt and numerous others get away with it? Because they use a boost-referenced fmu and are not relying on the airflow-referenced maf at WOT. Once they reach 350 engine hp the injectors are at 100% DC (since the ecu detects that the maf is maxed out). Beyond that point the additional fuel is provided by the fmu. The problem with using an fmu is that it starts pumping up fuel pressure considerably earlier than the maf hits its maximum, so you end up being pretty rich at midrange. Using a Z32 maf allows airflow-referenced fuel delivery up to 420 hp.

The Z32 maf is identical in outward shape to the A32 maf, so it bolts right on, but you need to have the ecu programmed for it.

 

so if I were to tell technosquare that I have a Z32 TT maf, they would be able to program that in, how would they do that?

so with a Z32 maf, I wouldn't need an external FMU? and therefore I wouldn't have to worry about my A/F?

 

You'd have to ask technosquare, JWT is the only people I know of that can program that into the ecu.

And yes, that's the point of having technosquare setup your ecu, so you have no fmu.. BUT, you still may need to fine tune your a/f with a SAFC. Only way to really tell is dyno with A/F

 

and you need bigger injectors or they will be maxed just like the stock maf

 

So what if you have a e-manage w/ the Z32 Maf, would you still need to have your ECU sent in to JWT

 

Also, JWT claims that if you have the Z32 MAF it needs to be on the non-charged side (before the Turbo/SC) and at least 18" from the Turbo/SC. <non-charged side>

2 people however have gotten it to work on the charged side with the JWT Program. I haven't been able to. So results vary.

IanS

 

wait, so I were to keep my maf and just get a FMU, how would I avoid running ultra rich...??

when do our injectors max out? hlh is using stock injectors....does that in effect lean the mixture out for him...b/c they can't keep up with the load therefore it evens out the FMU's rich mixture?

can't I just use a SAFC to control it so it doesn't get extremely rich in the mid range? or e-manage? how would that work?

 

so if you are running less than 350 crank hp, you can keep our stock maf's and the a/f will still be just fine....so you won't need a FMU?

 

Your asking to many things at once.

And don't referrence someone else's car, unless you know what they are running and why.


1. Only use FMU. Yes you will run rich. What is ULTRA rich? I am @ 10:1 @ 3900 rpm , but @ 6500 rom I am @ 12.3

You use the best disk for your application.

 

Get some type of air fuel controller to fine tune and you can avoid running ultra rich. I have the stock MAF, 370's, FMU, and the emanage. Around 4k, the car starts to run rich because the FMU starts to bump fuel pressure due to boost, we turned the injectors down there with the emanage. Not a perfect system, but it works.

And hlh is pushing his stock injectors way beyond anything they were designed for. Not a good idea. The fuel pressure he runs is in dangerous territory. And look at his A/F curve sometime, his dyno plot is somewhere, it's not pretty.

Basically, most boosted Maximas run a bunch of bandaids because we don't have a good solution to fuel. Other cars get standalones, custom ECU's, and so on. We have to piece together the fuel management.

 

But any car can run a standalone, can it not? Just costs a crapload for a Motec or whatever other standalone you decide to use, and to tune.

 

We can use standalones, ie the AEM EMS or Motec would technically work with our car. Just a little more difficult due to the direct ignition, and the fact that we'd lack any kind of technical support.

 

What about using J&S knock guard with Emanage programed for 550cc injectors and Q45 MAF ? I have a Q MAF off my old SR20 I used to have, according to JWT Q MAF is good for 600HP. Also JWT is able to program a Ford Mustang Cobra '93 MAF using a subtractor program which will be good to 700HP. Cobra MAF is made by Hitachi just like our Nissan ones, it runs about 120 bux new. Subtractor program basically doubles the MAFs ability to read high HP.... at 350WHP you will be topping out 5V on the MAF, with the subtractor program it will read 2.5V at 350WHP. I know this is the case in the SR20 world.

 

very interesting idea....I'll have to call JWT and ask them about this subtractor thing!!! and maybe have it done to my A32 maf...

 

Keep in mind that there is a trade-off of air-flow measuring resolution involved with using higher flow capacity mafs.

The ecu in all cases deals with a 0 to 5.1 V signal from the maf. The ecu compares the maf signal to a reference voltage in lookup tables that determine timing and afr (along with TPS and knock sensor data). The lookup tables are a finite size by necessity, so the reference maf voltage is digitized.

The trade-off involves the resolution of the reference voltage in the lookup tables. A high flow maf like the Q45 can meter significantly higher air flow than the A32 maf, but is still limited to the same number of discrete voltages as the A32 maf. This results in a coarser digitization, and a rougher approximation to the voltage the maf is actually sending to the ecu. This may cause the engine to feel not quite as smooth while accelerating or even when cruising with only slight modulation of the throttle.

Does it matter? Probably not, except in extreme cases. I didn't notice any difference when converting from the A32 to the Z32 maf.

 

AWESOME post stephen