hally

this experiment would clarify big injector & stock AFM fueling abilities:
1) take your favorite AFM chip, edit FQS table to accomodate big injectors (scales back to stock equivilant fuelling for identical idle, PT and WOT map values)
2) now edit the WOT fuel map, puttting maximum value 255 (FF) in the upper RPM bytes. (for a k26 running 16-18psi you might see up to 150ish values here = 150 / 128 = 117%)
I am guessing you will run very rich even with a big *** turbo, as map values dominate over load in WOT calculations, so the AFM being maxed out is not that relevant (thats why a piggy can't help much here) 255/128 = 199% scaling factor, (i am unclear of the precise weighting given to this factor, but my a/f ratios certainly are very responsive to small changes, if we knew this weighting we could clarify this theoretically)

Actually if that didn't supply big enough duty cycles, you could increase the FQS scaling factor and reduce all then map values buying you more range. Idle map values are in the 30ish vicinity so there is room to scale down a fair bit.

Transaxle

That's right. This picture shows the AFM (LMM) signal at a WOT test drive. It reaches it physical limits at about 5000/min - that's how the DME expect it and every AFM replacing MAF should do. The more challenging part is during the shifting. The AFM flap closes completely when the BOV opens - and that is not so easy to simulate with a MAF.

Duke

Perhaps I misread your post...

But it seems you are missing a vital point. The limit of the AFM (or any flow metering device as Tomas pointed out) is not that it's limited to X amount of fuel.
You can't "buy more range" because everything above a certain flow results in the same voltage meaning you don't get any resolution. And that's the limit.

hosrom_951

That why why the Greddy unit i have could run sub-injector mode when the AFM get's maxed out.

I haven't maxed the AFM yet, and i am running 72lbs injectors and a bigger turbo.

UK952

Can you explain sub injector mode further please? Not something I have come across before.
Tony

hally

understand what u are saying Duke on metering, i was just attempting to clarify the fuel side of things in that u can still add more fuel even if the meter is maxed out by editing the chip WOT map.

hosrom_951

The eManage is set to give out a certain voltage by the user (0-4.6v in my case), during normal operation.

When the AFM is maxed, the eManage see's that the voltage comes in at say 5v, there is a software/programe in the eManage called sub-injector mode, which only comes in when the AFM is maxed out.

The sub-injector mode is basically where the eManage controls the injectors when the AFM/MAF is maxed out.

By using this, one must set the target AFR in the sub injector mode, the unit will compensate for the difference and give out correct voltage for the DME, but will still control the AFR.

Basically, the eManage acts like a temporary DME/ECU when the AFM get's maxed out to control the AFR.

Offcourse, the user should enter the desired AFR in the sub-injector mode at the rpm wher ethe AFM gets maxed out.

Like i said, i still didn't max the AFM just yet

Hope it makes sense

jimbo1111

Hi Tomas. I have a VR maf and love it. I am just pointing out that an afm signal can still be use efficiently with maf and larger injectors. First let me point out that a maf has the ability to spread load out using larger injectors. This might come as a surprize to you but it's bin done for years. All I have stated is if someone sizes a maf meter to the same output as a afm. The output signals will be very close. When one installs say 55lb injectors. The load spreads out evenly and will allow the maf an additional 37% before it maxes out. If you don't believe it's possible. That fine. LR and many others tune this was. The only thing I believe that they lack is a maf sized to the specs of a afm. They use off the shelf mafs witch throw off the output. For instance. If someone uses a 24lb maf they are off by 20% or so. This will be ok if you run stock injectors and with a little voltage manipulation but once larger injectors are installed it compounds the offset making it difficult to setup a good part throttle. VT truly has a very good system. Programing the chip for any off the shelf maf is great. I'm assuming that's the way you are intending to do it. Don't over look what I have stated. It's a different approach that can work. I'm not selling anything. I don't ever plan to. If someone can disprove me than do so. I Think it's pretty easy to recalibrate a maf. I have said this before. It's pretty simple. Install a maf infront of the amf. Power both units up data log both systems at the same time. Write down the value that the maf puts out at idle. Than go for a full throttle run. Assuming one can max out the afm with a larger turbo. When 4.7 volts is achieved by the afm. Write the voltage output of the maf meter down. Send the maf to pro m or who ever has the ability to recalibrate it. The voltage will tell them what cfm rate you require at idle and max output. They will recalibrate the meter to the same cfm as the stock afm. Explain to me why this will not work?

streckfu's

Well in that case, you may find some good Huntley or Windward stuff on E-bay.

There are plenty of MAF users out there that are offering their experiences. I can only emphasize the resounding satisifaction with John's products that is expressed on this forum.

I can tell you to stay away from the APE products (Autothority). The were the King 10 years ago but far better products are available today.

Happy hunting.