S-AFC idea

[Marlon]

i was thinking about why the s-afc won't work well on out cars(cause when in wot it has a preset fuel map) and i was wondering if anyone has tried running a safc but not letting the stock ecu know that your are at wot, only letting the safc know, so then u can still have 2 different fuel maps one for crusing and one for wot

would this work

[Marlon]

anyone

[maldo]

That is the reason it doesn't work effectively with "our" cars. The TPS is an on/off version, it does not provide a signal for anywhere in the middle of the on/off signal. So in effect, the low throttle setting is anything that is not at WOT, high throttle setting is only at WOT. A remedy to this, and a mod that many have started to do is to remove the TPS as the actuator and replace it with a MAP sensor. A MAP sensor will give you the low throttle setting for essentially all stages under vaccum and high throttle setting for everything under boost.

Here is a tech article for the mod: Fooling the S-AFC

I hope this is what you were getting at, if not, clarify and I will try to help further.

[cjthor]

When I go to the monitor part of my AFC I see more than either a 0 or a 100 percent. It is not just an on or off thing. Maybe the DOHC guys dont have this problem? I sure dont.

<small>[ January 18, 2004, 12:05 PM: Message edited by: cjthor ]</small>

[maldo]

When you go and monitor the input voltages, what voltages are displayed for the TPS? You should see approximately 0V and 5V. Possibly the DOHC versions had a TPS with variable voltage, in that case the S-AFC would work as it is supposed to. Not sure why yours would have a variable TPS when not even the Miata came with one.

[cjthor]

Almost positive its variable. I will check today.

[Marlon]

the S-AFC only has 2 fuel maps right
so then why do you need variable tps?

[maldo]

The simple on/off TPS that the MX-3 has will provide the low throttle fuel map for all conditions other than WOT which is when the high throttle map takes over. Essentially then, 99% is covered by the low MAP and 1% is covered by the high MAP. The benefit of the variable voltage TPS allows blending, meaning that when you set your S-AFC to have the low map for all voltages 80% or less of the max voltage it will do so, likewise 20% of max voltage or greater will be the high map. It will allow better tuning under acceleration.

[monty73741]

u know.....
i saw an article where they converted a miata maf to map, but superstreet doesnt have on there site anymore, i was thinking i could be done on the mx-3...i might try when my mx isnt a daily driver anymore

[cjthor]

Ok for all you guys with an afc. When you are on monitor mode what does your throttle percent show...does it progressively go up or is it just 0 and 100 percent.

[maldo]

0 or 100%, never in between.

FYI, the Superstreet conversion from MAF to MAP was with the installation of a FM link.

[cjthor]

FYI guys the DOHC TPS is variable. 0-4.5 volts.

[maldo]

Lucky for you.

[monty73741]

yeah i know that the link was for a fm link.....
but would the conversion be possible in the mx

[BATTOSAI]

In my Gs the TPS voltage raises progresive and accurate, and the S7afc works on Wot or partial. It has been shown on my A/f ratio gauge!