DSM AFC - A New Way Of Thinking...

[Maxx Mazda]

Basically, can the DSM AFC be used to control fuel trims while in vacuum? That way, I can do away with stalling without having to relocate my MAF. If I can tell the car how much fuel to get as soon as the car enters vacuum, it won't stall. Now, that being said, it will only modify the MAF voltage, correct? So if the MAF is stil lseeing a s*** ton of air (it's mounted just before my turbo) the AFC can only modify that signal, and I will still stall in theory, correct? I was looking at the PSC1 manual, and there is an alternative way of wiring it, so that instead of modifying MAF voltage, it connects directly to the ECU and will take manifold pressure, and output it as a raw value. If we can determine what the voltage values are for say 100%, 20%, etc. we can in effect remove the MAF completely and tel lthe stock ECU how much fuel to add based on the boost pressure sensed by the AFC.

Am I smokin crack here, or does someone follow me?

 

[03MSP]

Just get the damn Microtech!

 

[Moeed]

PM igdrasil. He did it with an mpi.

 

[MSP608]

it doesnt stall bc the car goes into vac. it stalls/dips bc the maf reads air thats actually not going into the engine so it dumps in fuel. i dont see you being able to modify it so it doesnt over rich itself between shifts but then not go too lean at idle.

 

[Maxx Mazda]

^^^ That's what I thought, however that being said, isn't it possible to use the AFC instead of modifying the MAF signal, it instead outputs the pressure based fuel trims in place of the MAF signal, and the stock ECU takes that and adds fuel?

 

[igdrasil]

It can be done, however, it can take weeks or a month to make the car run right, its not difficult, its just need some work. Depending on the MAP resolution (2bar, 3bar) the highest, the difficult.

You will have to at least to find the voltage that makes the car idle, then you start from there.

I dont know if my thread can help, but at least is a good start, I dont know how the DSM AFC works or what can be done, but if it can receive a voltage signal and adjust the output...it can be done.

http://www.mazdas247.com/forum/showthread.php?t=96397&highlight=maf+map+conversion

 

[Maxx Mazda]

Check it out:

http://www.airflowlogistics.com/psc1-001_ds.pdf

I think if I wire it up in the "signal modify" mode (second one down) I can basically output the MAP reading as a raw voltage, and like you said go from there into the ECU to tell it how much fuel to add, etc. It will take a LOT of tuning I'm sure... Wideband and laptop. Do you think that would work best? Or do I run it i nthe "programmable MAP sensor" mode (the first one?)

 

[Maxx Mazda]

Just re-read it, and I think i want the first mode. Basically, at "x" boost / vac pressure, output "y" voltage to the ECU. Simple as that. Where it complicates is matching the voltages to what the MAF would send. I basically need a range. IE: "q" volts is max vacuum the car will see, and thus least amount of fuel. And "t" volts is max ECU can see, giving 100% injector duty cycle. Am I thinking about this the right way?

 

[igdrasil]

Problem is, the fuel curve will be affected very little, at least thats what I learned from the stock ecu. Even if you output 4.99v it wont open the injectors full, it will just add a bit and advance a lot of ignition timing.

 

[Maxx Mazda]

Okay, is there any way to directly control the fuel delivery, through the stock ECU? I know the MPI uses additional injectors and leaves the stock ECU alone, but that's not my objective here. I know I could go and buy a Microtech or whatever, it's not a money issue, I'm actually intrigued and want to do this. The Split Second AFC is capable of doing what I want, I jsut need to figure out how.

 

[igdrasil]

Okay, is there any way to directly control the fuel delivery, through the stock ECU? I know the MPI uses additional injectors and leaves the stock ECU alone, but that's not my objective here. I know I could go and buy a Microtech or whatever, it's not a money issue, I'm actually intrigued and want to do this. The Split Second AFC is capable of doing what I want, I jsut need to figure out how.

Not that I know, I didnt try with the MPI, but its a possibility you just have to try. I think the emanage can do it but I havent tried it on the protege.

 

[Maxx Mazda]

Sorry ma, I read your other thread completely. Did you use the MPI to modify the signal to the stock ECU or what? I thought that's what you did?

 

[igdrasil]

Sorry ma, I read your other thread completely. Did you use the MPI to modify the signal to the stock ECU or what? I thought that's what you did?

Yeah, I first played with it in parallel, both the map sensor and the MAF were installed. Used one of the wires, probably the Coolant Sensor wire which was unused...to monitor MAF voltage and the MAF wire reading the MAP sensor.

So, I know the car idles around 2.3v so I set the output voltage to 2.3v when in 20in of vacuum. Lets say the MAP sensor reads .15v when in idle and 2.0v when on 0vac.

For example (using hipothetical numbers):

MAP - MAF
.15v - 2.3v (when the MAP reads .15, adjust so the output send 2.3v)

2.0v - 2.7v (when the MAP reads 2.0v adjust so the output send 2.7v)

So the best way is to keep the maf and try to get the voltages closer and you are done.

 

[igdrasil]

This is a 2bar map sensor voltage matrix:

Manifold Pressure
(relative sea level / absolute)2 Bar
MAP Output
14.31psi / 29.01psi - 4.90V
14.00psi / 28.70psi - 4.84V
13.00psi / 27.70psi - 4.67V
12.00psi / 26.70psi - 4.50V
11.00psi / 25.70psi - 4.33V
10.00psi / 24.70psi - 4.16V
9.00psi / 23.70psi - 3.99V
8.00psi / 22.70psi - 3.82V
6.00psi / 20.70psi - 3.47V
4.00psi / 18.70psi - 3.13V
2.00psi / 16.70psi - 2.79V
0.00psi / 14.70psi - 2.45V
5.00inHg / 12.24psi 2.03V
10.00inHg / 9.78psi - 1.61V
15.00inHg / 7.33psi - 1.19V
20.00inHg / 4.87psi - 0.77V
25.00inHg / 2.41psi - 0.35V
29.10inHg / 0.40psi - 0.02V

 

[KySpeed]

see if a HKS EDIS will work with your guys's car. They work on evos

 

[Maxx Mazda]

Did you find that matrix somewhere? It's a 2.5 bar MAP sensor. I'm seriously gonna try this. It can totally work. If I go off what you said, that at 20in of vac, it will output 2.3V and at 0 vac, output 0.15V or whatever I can do it.

Does the MAF input signal only control fuel delivery, or timing as well? See, the MAF sees air only, and same with the new MAP sensor. So, it's basically a different way of measuring how much air is getting to the engine. I don't see how that could cause any problems per se', but this is gonna be a b**** to get working the first time. Once I get a sweet tune though, it'll be phat!

 

[igdrasil]

Did you find that matrix somewhere? It's a 2.5 bar MAP sensor. I'm seriously gonna try this. It can totally work. If I go off what you said, that at 20in of vac, it will output 2.3V and at 0 vac, output 0.15V or whatever I can do it.

Does the MAF input signal only control fuel delivery, or timing as well? See, the MAF sees air only, and same with the new MAP sensor. So, it's basically a different way of measuring how much air is getting to the engine. I don't see how that could cause any problems per se', but this is gonna be a b**** to get working the first time. Once I get a sweet tune though, it'll be phat!

Yeah, it will adjust both timing and fuel, but in small increments based on a standard map, not full control.

For example...if you are in 4500 rpms and the base map says 25deg of timing advance and 4ms on the injectors with 3.1v on the MAF, sending 4.5v to the ecu will probably output 29deg of timing advance and 4.5ms of injector open time.

The same if you put lower voltages, it wil retard timing and and cut injector open time.

 

[Maxx Mazda]

Okay, but thats not a bad thing completely. Agesssive timing is good for power, and as long a the ECU is then in turn adding more fuel as well to compensate it'll be great. Because with the 440's, I'll want a slightly shorter injector open time since they flow so much more, correct?

 

[FunkyBuddha]

Nick, by the time you figure it all out, you'd have your own standalone

 

[Maxx Mazda]

This is fun and cool to me. I wanna make it work damnit! Glen, you know how stubborn I am when I want somethign to work.