S-AFC install wire question
07-01-10, 06:33 PM
#1
WTF is a Piston?..Anyone?
Thread Starter
S-AFC install wire question
hey guys this might be in the wrong section so mods if it is im sorry i just need a fast answer.
kk i bought a car with a SAFC alredy installed. the PO did a good job but for some reason had the TPS wire that needs to go to the safc spliced in from a BROWN/Red wire off the car harrness. after looking at a wiring diagram in the FSM it states the TPS wire is Green/red.
this being i the case i know its an S4 car so it wont rread the throttle position past 45% approx. it will just assum after that its WOT.
question is what way is best? is there a reason he used the brown wire. (wire in FSM says its for the boost pressure sensor) or should it be hooked up via the green/red (which in FSM is the TPS wire) then just set up the SAFC accordingly?
kk i bought a car with a SAFC alredy installed. the PO did a good job but for some reason had the TPS wire that needs to go to the safc spliced in from a BROWN/Red wire off the car harrness. after looking at a wiring diagram in the FSM it states the TPS wire is Green/red.
this being i the case i know its an S4 car so it wont rread the throttle position past 45% approx. it will just assum after that its WOT.
question is what way is best? is there a reason he used the brown wire. (wire in FSM says its for the boost pressure sensor) or should it be hooked up via the green/red (which in FSM is the TPS wire) then just set up the SAFC accordingly?
07-01-10, 07:44 PM
#2
http://www.1300cc.com/howto/how2/safc.htm
Should be hooked up to the TPS, thats odd he spliced into the boost sensor. I am not too familiar with how the SAFC works, but if it has the capability to modify the pressure sensor signal also then it should be ok. The link above shows a guide specifically for the SAFC though.
Regardless, there should be a calibration on the SAFC for the throttle so it "knows" what 100% open and closed are. So don't worry about the issue with the TPS only reading to 45%, the SAFC will take this as 100%...
Should be hooked up to the TPS, thats odd he spliced into the boost sensor. I am not too familiar with how the SAFC works, but if it has the capability to modify the pressure sensor signal also then it should be ok. The link above shows a guide specifically for the SAFC though.
Regardless, there should be a calibration on the SAFC for the throttle so it "knows" what 100% open and closed are. So don't worry about the issue with the TPS only reading to 45%, the SAFC will take this as 100%...
07-02-10, 12:52 AM
#4
This is an n/a engine? He hooked it up to the MAP sensor because it will provide a wider range single than the factory s4 TPS.
The s4 TPS will read full voltage at like 40% throttle as you've said. The n/a 1 bar MAP sensor will read full voltage at atmospheric pressure, which corresponds to WOT. It's pretty much a bandaid to account for the fact that the s4 cars do not have a full range TPS. There is at least one writeup about this floating around. It's kind of an oldschool thing, people were discussing it a lot when I joined the forums in '04.
Just leave it.
The s4 TPS will read full voltage at like 40% throttle as you've said. The n/a 1 bar MAP sensor will read full voltage at atmospheric pressure, which corresponds to WOT. It's pretty much a bandaid to account for the fact that the s4 cars do not have a full range TPS. There is at least one writeup about this floating around. It's kind of an oldschool thing, people were discussing it a lot when I joined the forums in '04.
Just leave it.
07-02-10, 06:15 PM
#5
WTF is a Piston?..Anyone?
Thread Starter
no this is a turbo 2 motor so would it not mess with the voltage range as it goes from manifold vac to 0 to 10 psi? i already changed it to the tps wire but would i be better to switch it back?
07-03-10, 10:35 PM
#7
people actually OFTEN use the map sensor instead of TPS for wiring the AFC. our TPS is so narrow ranged compared to our map sensor...at 1/3 throttle the tps voltage is maxed out.
it uses the map sensor signal as the tps signal, allowing you to tune for boost% values instead of throttle% values.
the biggest drawback is if you have boost dropoff...then using the TPS may be more beneficial.
it uses the map sensor signal as the tps signal, allowing you to tune for boost% values instead of throttle% values.
the biggest drawback is if you have boost dropoff...then using the TPS may be more beneficial.
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