Remove the SAFC's grey wire from the tps output wire that it is connected to now.

Now connect the grey wire of the SAFC to the brown/red output wire of the boost/pressure sensor. You need to do this before the brown/red wire gets to the FCD if you have one.

If you don't have a FCD, then just connect it to the brown/red wire at the ECU. I THINK it's pin 2A

About the afm. Do this. Take the air filter off. Turn the key to ON. Push the afm's vane all the way to open. Observe the SAFC as you do that. It should go to about 100 percent. Do that several times and hold it full open for several moments.

What you might do with the pressure/boost sensor is put a MittyVac on its vac port and put some pressure on that port around ten or so psi and hold it there for several moments. Look at the SAFC and the *TPS* reading should go up as you do that.

You do those things because.......someone convinced me that the SAFC needs to LEARN, and you make it learn by doing the above. I'm not so sure after thinking about it for a while, that this NEEDS to be done. I'd do it just to see that the afm and *TPS* readings will respond to inputs from the afm and boost sensor (TPS).

 

ok that idea about the afm sounds like a good one, ill just even see if it will read 100 percent, then if it doesnt and only reads the 49% at least i know its opening all the way, but if it does read 100% when i do this how do i correct the AFM so it will open all the way, just get a new one or what?

about the TPS one i do have a FCD its a racing beat one, so where would i re wire the TPS wire from the SAFC to exactly?

 

The AFM.......it's probable that your not getting it to go full open. You have to be at wide open throttle and under fulll boost for it to go wide open or 100 percent. I'd guess there's nothing wrong with the afm.

The TPS......you need to buy about ten feet of 18 to 20 gauge wire and run it from the grey wire at the SAFC into the engine bay to the connector on the boost sensor. Find the brown/red wire on the boost sensors plug. Attach the new wire to that brown/red wire. Your choice on making the connection. Solder, crimp, whatever.

 

Just as a note........I notice that if I watch my boost gauge and the SAFC Monitor at the same time, the safc percentage will be approx 50-53 percent when the boost gauge hits zero.

Just in case that did not make sense right off.....usually the boost gauge reads below zero, or in the area of 15 in/hg (ah, heck, reads vacuum, I might have gotten the in/hg thing wrong), but as you apply the pedal to the metal the needle gets to a gauge pressure of zero and anything above that is boost pressure.

Also if the key is to ON and the grey wire is connected to the boost sensors brown/red wire, the voltage in Sensor Check, reads approx 2.2 volts. As you boost, the voltage will RISE and get up there around four volts or so. I forget the max right now. Dependent on how much boost your engine/turbo makes.

On the afm it's just the opposite. The voltage drops as you press the pedal to the metal.

Bottom line is that my HIGH throttle setting begins around 53 percent or as you figured out....just when the boost comes on line.

 

OK so i did the AFM check and on the SAFCII when i hold it full it reads 84% and i still dont hit 84% under full boost and flooring it, i hit around 50% tops.

next question about that TPS to boost sensor swap, im planning on taking my car into the dyno shop to tune , is this a good idea to do before hand or should i leave as is?

 

On your S4 you want the S-AFC's throttle wire connected to the pressure signal.
If not you will be doing another dyno session later.

 

So... leave it like i have it (connected to the TPS wire at the ECU) or re-wire it to the other spot in the engine bay before the FCD???

 

There you go..

The S4 TPS is not linear, the pressure sensor is.
And, the pressure sensor reflects other variables like ambient air temperature, TID & exhaust mods.

Here's an example: When the air cleaner is a little dirty, boost is reduced, so the S-AFC backs off the high map some.

 

ok, so where abouts is the boost pressure sensor located under the hood, my FCD is racing beat if that makes a difference.... and its a 87 TII, thx..

 

bump.

 

You want to tap the pressure signal between the sensor & the FCD, right at the sensor on the front of the right front strut tower.