Hello everyone,
i did the TB mod (S5 TB on my 84SE), and was wondering how much gap there should be between TB plate and housing/wall at rest? I noticed the TB stop screw was hardly bumping the plate open at all. The FSM seemed to be a bit unclear for me to understand.

 

if it hasn't been touched (the seal is still there) then its best to leave it alone. in the stock system the throttle plate is mostly closed, and the BAC supplies any additional needed air

 

S5 NA M/T TB primary plate gap 0.020"-0.030"

 

Thanks guys. Yeah the seal is missing, so the TB stop screw was messed with in the past.

Hotdog, I did see that in the FSM. But it's asking you to measure the primary gap when the secondary plate starts to open. I don't have a secondaru plate. That's why I am wondering what the primary plate gap should be at rest in light of the TB mod. If I'm missing something please explain.

 

Ok, now I see what you're saying. Like j9fd3s said, the throttle plate is mainly closed in the stock system. Since you got no reference point, I'd just tighten the screw until it makes contact when the plate is closed and then give it an additional 1/4 to 1/2 turn. Readjust if necessary once the car is running and warmed up.

 

Unless I'm missing something, I think there's a misunderstanding here.

When you do the throttle body mod you remove the double throttle system. It's the two throttle blades closest to the mouth of the throttle body with the little vacuum actuator. On S5s I think it has a spring too, but that's beside the point.

The secondaries that the FSM mentions are the blades further down the top two bores. You obviously didn't remove those for the TB mod, because if you did the car would redline immediately on start from all the extra air rushing in.

So the FSM spec is measured based on when the two secondaries deeper in the throttle body by the primary blade open up. Not the two outer blades removed in the TB mod.

 

Thanks hot_dog. Since I was shooting for a 1K idle, I did what you said and turned the screw in until I got it up to about 900 (air adjust screw all the way in). Then I turned the air adjust screw out about 1 1/2 turns, which brought to about 1K. It idles exactly where I want it now.

 

and then since you moved the throttle position, you need to do the TPS too

 

Roger that my friend. I calibrated the TPS in the Haltech. But for some reason it shows 1.8% at rest.

 

Yes, I believe you are correct. I explained myself a bit unclear.