Mindspin311

Ok so I am having my car street tuned with a wideband today, what AFRs should we try for, both low and high boost.

YellowT2

iTrader: (1)

What do you mean by "low" and "high" boost?
What kind of gas (octane) are you tuning for?
How safe do you want your map to be?
Are you using the stock ECU for ignition? If so, do you do anything to retard the timing above 8.6 PSI?
Are you using any water/alchohol injection?

Mindspin311

Low/high for a point to switch over when adding more fuel
93 octane, only thing I can run
I would like it to not blow up, I was thinking 10psi
Stock ecu, no correction
No injection

SureShot

Many run 14-13 during low boost & 12-10 in high boost.
The spark timing is critical.

The THR % determines which map the S-AFC is using.
Sometimes, especially in cold air, the boost gets ahead of the throttle
I wired the THR signal to the pressure sensor (before thr FCD.)
My low THR threshhold is 50% which equates to about 1PSI boost.
My high THR setting is 85% which is about 11PSI.

After it's tuned, post up what your S-AFC settings end up at.

Mindspin311

So do you reccommend switching with throttle and not boost?

Mindspin311

So uo to 50% you are at low, and above 85% you are in high, what about between 50 and 85?

SureShot

The S-afc interpolates between the maps to give a smooth transition.

Using the pressure sensor is a little safer & saves gas.

Mindspin311

Well what map are you running between 50 and 85? I understand you are on a low map below 50 and a high map above 85, but what about inbetween?

SureShot

I have a switch on the console that bypasses the MBC to hold low boost & save gas for daily driving.

Mindspin311

Thats pretty cool, how did you do that? Are you running stock fuel between 50 and 85% throttle?

SureShot

The S-AFC averages the difference to give in-between values.
It also does it in between RPM steps.

Mindspin311

Also I was told to run the TPS wire into the pressure sensor (MAP?) pin on the ECU, would that be a better idea? Run low boost up till1-2psi, stock fuel till say 6psi then have it switch over to high boost after that?

Mindspin311

Ah, so inbetween 50 and 85, its doing its own thing and averaging your low and high values.

SureShot

Here's the schematic:

Mindspin311

So, work off of throttle position, or switch my throttle wire to the boost sensor?

SureShot

The ECU will see WOT 5 volts as about 15PSI if you wire it to the MAP input.
That would give you a fuel cut every time you go full throttle.
If you pick up the signal behind the FCD, you're clipping an important part of the correction map.

SureShot

When I was experimenting with the S-AFC, I wired it through this panel.

Mindspin311

So stay with throttle it is, what is that in that picture?

Mindspin311

up

Mindspin311

so 14s under vac and down to low 12s under boost

SureShot

You might find something like the switch on the right useful.
It just switches the line to the S-AFC’s THR signal to source either the TPS or the pressure sensor.
That way you see which works best for you.

SureShot

D/P