abuelo ralliart

Yes guys, it is possible (with a little work); an it is not being connected to the map sensor (it does nothing that way - I've tried it too). Im using this setup with de maf sensor for about 2 months now with no problem...

First, thanks to Dangerous Dan for the tips he posted that lead me to the solve of the mistery.

What is happeing here is a load incompability between the ecu and the apex unit; meaning that the ralliA ecu has a 1k ohm internal resistance that is not very compatible with the safc. How to do the intstall:
First let me clarify that ralliA maf IS a hot wire type.

1) Install a 1k ohm resistor between the maf signal and ground so that the maf "sees" that load if you dont it will send 5-7volts to the safc. Do it between the black and the white cables of the safc.

2) Now, the safc doest not have enough power to cope with the ecu resistance so you need to raise the power of the apex output. I used an LM358 operational amplifier configured as a voltage follower so it mantains the voltage but gives more power (current), I used the LM358 because it can be operated with positive and ground voltages (not dual power), becuase it is very chap (less than one dollar - at lest in mexico), and because you can find it in any electronic equipment store. Connect number 8 pin to swtiched 12 volts (safc red cable), pin 4 to ground (black cable), pin 3 to the safc output signal (yellow wire) and finally to make the voltage follower join pins 1 & 2, this last will be your signal output to the ecu (pin 64).
Do not solder directly to the opan or you will fry it; use a base to solder the wires, and the plug the chip to it.

3) Configure the safc as sensor type: hot wire, sensor No. 3 - 3 & sensor cal 1 - 1.

Use APEX wiring diagram M7-a.

This really works I tested the results with my wideband, and now I can really control my air/fuel ratio!!

If you are buying a new piggy back for your ralliA I would recomend to go for a rrm but if you aready have a apex or found a bargan used one (like me) it is worth the trying.

abuelo ralliart

by the way the link to the LM358 datasheet: http://www.datasheetcatalog.org/data...r/DS007787.PDF

RalliDew

can you define what pins are on the lm358 and the pins that are on the ecu , to me its confusing

abuelo ralliart

Of course, (thought it may be confusing).. all pins I'm refering to are on the lm358..except for: "ecu (pin 64)"

All other lm358 conections are refered to the apex wiring, thought it would be a little easier to understand thay way..

Any way, give me a couple of days to make a diagram so it's easier to undersand..

RalliDew

k thanks ya i read it slower it made more sence but i cant seem to find the lm358 with out an m or an n or somthing on the end of it
do you have a link to a website that would have it cause the ppl at radio shack or dumb.

Edit : if its not to much trouble c an you take picutres and define them.

abuelo ralliart

any of the lm358 series should work, the difference comes on the housing, pin form and some voltage and current characteristics. I think I'm actually using a lm358n......if tomorrow I get home early (while there is still light) I'll take the pictures.

abuelo ralliart

you can find them at newark.com

http://www.newark.com/jsp/search/res...isGoback=false

abuelo ralliart

Here is a photo as you can see it is "encapsulated" with tape...
You can also find a diagram. Hope this makes things easier.
Remember do no solder directly to the lm pins you will fry it, use a base.

RalliDew

what do you mean by " use a base" as in heat the solder first then touch it to the lm and let it cool w/o letting the gun touch it?

abuelo ralliart

It can also be done that way....actually I did my first prototype like that and worked fine. But when I did my second I damaged the lm. So all that I am saying it is safer using a 8 pin base (they are very very cheap).

If you have a good (not mine) and are handy enough (no me ) you can do it

DangerousDan

iTrader: (8)

that's fantastic. nice work.

what's your tune look like, since you have a wideband?

abuelo ralliart

Thanks Dan! I was a LOT of work..
About the tune, well I removed the turbo 'cause my custom manifold craked, so I will re make it and get bigger inyectors...but that will have to wait a while; I'm running a little low on cash right now
So now that is NA again (hopfully not for long) it really helps i didnt think it would change that much with only this... the car is bone stock except for the SAFC. Im aiming for a 12.8 afr at wot; before the mivec switch I'm adding between fuel after that Im decreasing a little.

DangerousDan

iTrader: (8)

I bought some amplifiers to see if this will work with the mpaecu2. I'll post up in the next few months with an update hopefully.

cyanide

iTrader: (4)

Hi. Did you actually get the MAPECU2 working with this modification?