Ideal fuel ratios?
Ok so I am having my car street tuned with a wideband today, what AFRs should we try for, both low and high boost.
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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? |
Originally Posted by YellowT2
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? 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 |
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. |
Originally Posted by 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. |
So uo to 50% you are at low, and above 85% you are in high, what about between 50 and 85?
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Originally Posted by Mindspin311
So uo to 50% you are at low, and above 85% you are in high, what about between 50 and 85?
Using the pressure sensor is a little safer & saves gas. |
Originally Posted by SureShot
The S-afc interpolates between the maps to give a smooth transition.
Using the pressure sensor is a little safer & saves gas. |
I have a switch on the console that bypasses the MBC to hold low boost & save gas for daily driving.
http://208.62.166.66:82/guest/pics/9...C/TECH0005.JPG |
Originally Posted by SureShot
I have a switch on the console that bypasses the MBC to hold low boost & save gas for daily driving.
http://208.62.166.66:82/guest/pics/9...C/TECH0005.JPG |
Originally Posted by 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?
It also does it in between RPM steps. |
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?
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Originally Posted by SureShot
The S-AFC averages the difference to give in-between values.
It also does it in between RPM steps. |
Here's the schematic:
http://208.62.166.66:82/guest/pics/9...connection.jpg |
So, work off of throttle position, or switch my throttle wire to the boost sensor?
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Originally Posted by 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?
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. |
When I was experimenting with the S-AFC, I wired it through this panel.
http://208.62.166.66:82/guest/pics/9...itch-panel.JPG |
So stay with throttle it is, what is that in that picture?
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up
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so 14s under vac and down to low 12s under boost
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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. |
D/P
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