Educate me on primitive flappers

As most of you know by this point, i've recently become the proud owner of a 1990 MX6 GT Turbo. The plans at the moment are to daily drive it, and work on it some to be a more reliable DD, as well as to make some more power, and just enhance it overall without going overboard.

The current list of modifications installed on the car:
1) Supra 440cc injectors
2) Supra 50trim turbo
3) Tial 38mm external wastegate
4) MBC
5) FMIC w/ 2.5" piping
6) 3" exhaust
7) Greddy Type S BOV

Modifications being performed in the next week or so:
1) Innovate LC-1 wideband
2) Probinator EPROM ECU chip
3) EBC
4) AFPR(?) Question mark will be explained
5) Walbro 255lph fuel pump

My goals for this car, in terms of power and handling, are to make this into a decently competitive Challenge car, as well as an entertaining, but not entirely stupid DD. At the moment, on only 7psi, this car should run mid to high 13s, traction permitting. It is WAY faster than my roomate's DC2 Integra w/ H22a swap, which is a low 14s, high 13s car. It handles like absolute crap, due to blown struts and ridiculously high ride height w/ soft springs. The suspension, i can figure out. The tuning aspect, i can't.

The problem: The Mazda VAF throws out voltages that are outside the range of piggybacks such as the SAFC and Emanage boxes, and i'm not willing to make the commitment to Megasquirt at the moment, and any other solution is WAY out of budget. I MAY entertain the idea later on of piecing together the components needed to burn my own EPROM chips, but right now, that's more than i feel comfortable with. Previously on this board, i was recommended to try an FMU, which from my experiences, are fine for WOT scenarios, but the car won't be seeing WOT much, and i need to keep my driveability. In addition, the FMU creates a very mixed bag of responses on the MX6 forums, and almost nobody has one on their DD for because of the aforementioned problems.

I have the fuel to support 15-16psi, and would like to take advantage of that. All the Probinator chip really does is remove the boost cut, move redline up to 6800rpms (won't use it), and smooth out the timing map a bit.

Is there any glaring reason that i wouldn't be able to reach my goals using the modifications listed above? Do i even need the AFPR?

I apologize if this sounds like something i've already asked, but i don't think i went into this much depth, and this stupid flapper thing has me flummoxed. I don't understand how it works, i don't really understand the limitations, and i'm a little gun-shy of going to town with it.

Thanks!

I wonder if you could make a simple circuit to alter the output voltage of the flapper to what is required by the ecm/piggyback boxes...

RossD wrote: I wonder if you could make a simple circuit to alter the output voltage of the flapper to what is required by the ecm/piggyback boxes...

IF (and that's a big one) I remember correctly, the signal from the MX6 VAM is in the range of 0-10 Volts. Lots of VAMs work in the range of 0-5 volts. If you find a piggy back that supports 0-5V and the signal is no longer needed by the stock ECU, you can halve the signal simply with a pair of resistors (voltage divider).

Dang. I thought this thread was gonna be about cute skinny dancers in short skirts from the Roaring 20's.

kcbhiw wrote:

RossD wrote: I wonder if you could make a simple circuit to alter the output voltage of the flapper to what is required by the ecm/piggyback boxes...

IF (and that's a big one) I remember correctly, the signal from the MX6 VAM is in the range of 0-10 Volts. Lots of VAMs work in the range of 0-5 volts. If you find a piggy back that supports 0-5V and the signal is no longer needed by the stock ECU, you can halve the signal simply with a pair of resistors (voltage divider).

I'd still have to use the stock ecu to process that, since it's actually what would control the boost cut, etc.... To do what you're suggesting, i'd have to pretty much go with a full standalone, and if i go that route, i'd just ditch the VAF anyways, and go to a MAP, simply because i hate these things. From what i've read, it's 0-12v, too, making it worse. To make matters REALLY screwed up, anything over 75% throttle goes into open loop and the sucker just jumps to the full 12v right off the bat.

The stock ECU is capable of dealing with the higher boost applications with the chip... i'm just more wondering if i'll be able to control the fuel to at least the point that i won't damage my engine horribly with the stone age injector/afpr/walbro setup.

It's already running the 440ccs like a champ, with nothing to tune out extra fuel. I'm sure it's a little rich, it'll blow flames between shifts on occasion, but it's not like black cloud smoke screen like a lot of the turbo hondas and DSMs that i see that still last forever anyways, so i'm sure my cylinders aren't being washed or anything.

NYG95GA wrote: Dang. I thought this thread was gonna be about cute skinny dancers in short skirts from the Roaring 20's.

It can be about that once someone pats me on the back and says that my old school idea will work just fine to 15psi.

What about your list of modifications are you worried about? I thought your main reason for wanting the FMU (or something like it) was for idle and cruise conditions. If you're going to accept how its running now, then, sure you should be able to turn the boost up until your wideband says you're getting dangerously lean.

ANd if you want to add fuel on the top end with next to zero $$ go here:
http://gusmahon.org/html/fuel.htm and read up on the "extra injectors" section. Its ghetto, but it certainly works.

The stock ecu tune drops into the low 9s at full boost/high rpm so I'd bet you're not washing the cylinders anymore than stock

problemaddict wrote: What about your list of modifications are you worried about? I thought your main reason for wanting the FMU (or something like it) was for idle and cruise conditions. If you're going to accept how its running now, then, sure you should be able to turn the boost up until your wideband says you're getting dangerously lean. ANd if you want to add fuel on the top end with next to zero $$ go here: http://gusmahon.org/html/fuel.htm and read up on the "extra injectors" section. Its ghetto, but it certainly works.

I've already got plenty of fuel.... it's got 440cc injectors vs the 330ccs stock.

I guess i'm just wondering if going at it the way i am (440s, 255lph pump, and Adjustable fuel pressure regulator) is acceptable.

Strizzo wrote: The stock ecu tune drops into the low 9s at full boost/high rpm so I'd bet you're not washing the cylinders anymore than stock

Good point.... probably especially not with the much larger turbo on it...

Guess i need to just put the wideband on and start cranking the boost and keep an eye on it.

With the bigger injectors, you should be able to pop the lid off of it, and tighten the spring. That will buy you some range (room to add boost) back.

http://history1900s.about.com/od/1920s/a/flappers.htm

In the 1920s, a new woman was born. She smoked, drank, danced, and voted. She cut her hair, wore make-up, and went to petting parties. She was giddy and took risks. She was a flapper.

suprf1y wrote: With the bigger injectors, you should be able to pop the lid off of it, and tighten the spring. That will buy you some range (room to add boost) back.

Can you elaborate on this? I can add as much boost as i want with the EPROM chip that's installed, up to and past the point where the motor spontaneously grenades. I could turn the boost to 25psi right now if i wanted to run lean and melt all my pistons...

But if this gains me something, i'm more than interested.

The flapper is moved by airflow, and sends a corresponding signal to the ECU to provide fuel.

Install a bigger injector(s), more fuel is being provided, and less signal is required to send the correct amount. The flapper has a coil spring which the airflow must overcome to move it. These are usually adjustable. If you use your wideband, my guess is you'll see that you're already be rich. You should be able to tighten the spring a few notches at a time to bring your A/F ratios back to normal. The greater resistance will allow more airflow for a given position, and you can add boost without using all the flapper door movement, and still get enough fuel. It works, I've done it.

You could always add an extra injector in the intake tract, too. I made my own adjustable electronic extra injector controller. I can send you a drawing, if you want to build one.