S-AFC hooked up to boost sensor instead of TPS!
 

I am doing a turbo conversion- and I had an idea.

I currently have no way of controlling fuel under boost- just estimating by way of throttle, and adding it with the S-AFC.

My idea- Why not get a TII boost sensor (which measures boost and vacuum, unlike the N/A one, which only measures vacuum), and run it in parallel with the stock N/A one?
Tee the vacuum line to it- run power to it, and then run the signal straight to the S-AFC?? (not to the ECU at all)
I'd leave the stock sensor untouched- to the ECU.

I'd change the S-AFC mode from TPS to pressure sensor.
Wouldn't this give me control over fuel, dependant on boost and indirectly- throttle position/engine load?

Can't regular TII guys do this too, especially those with s4's, and their crappy narrow range TPS'S??

I see no reason why this shouldn't work!- Can anyone??

bump... is this such a dumb idea no one is bothering to let me know???

it's been done before.

Yeah, for TIIs w/ a FCD you basically have AFC low throttle position for pre FC voltage and high throttle for post FC votage from boost sensor. This allows you to add ALOT of fuel where you need it- after the computer no longer sees boost rising, but it is...

Ya- I did a search the morning for a related topic- and came across the fact that somebody beat me to this!!
I PM'd Chris Ng about it- he did it a while ago- so long ago that the threads he linked to have been deleted!

I just wanted to knoe if people changed the mode on the S-AFC or not.
This is a little different than with a TII computer- since the TII computer adds fuel anyways aunder boost. The NA ECU has no way of knowing about boost. That's why I wanted to use a TII pressure sensor, and use the S-AFC to accomodate for boost...
I'm still proud of myslef for coming upu with it though- but I guess I'm not the first one! (Damn.... like when I invented a screwdriver when I was 10...)

Inventing the screwdriver - that's easy!
Inventing the screw - now that's the hard part!!
:)