Hey guys, I swapped a motor in a 2001 A4 (B5 right?) 1.8T a while ago and managed to keep the throttle body from the blown motor.

I'm trying to get involved with the Formula SAE team at my school(http://metweb.spsu.edu/sae/initial.htm). They were talking about coming up with a new throttle body system, so I took this thing apart, diagrammed it, and measured resistances of what looks like a control system.

The idea is to develop a throttle system that open viariably in relation to pedal position. For example, at 50% pedal, the throttle pos. would open slowly to 25%. Then from 50% to 100% pedal, the throttle would accelerate toward 100%. If you were to plot a graph x=pedal pos., y=throttle pos. the graph would be a curve concave upward. The slope would be less than 1 until x=50%, at which it would be 1 and rise from there until 100%. The idea is to give a more linear throttle response from a butterfly style throttle body.

I've spent a good 3 hours searching through forums (here, audiforums, VAG-COM yahoo group, google, etc.) looking for some technical data on the system and perhaps a wiring diagram. There are 6 pins on the throttle body. I found that 2 (pins 3 and 5) are + and - for the servo motor, and 4 (pins 1, 2, 4, and 6) lead to the variable resistor array which follows the butterfly. It looks like pin 6 is reference voltage and the other 3 will show voltage with relation to throttle position. The resistance ranges vary, and some are curved. What I am trying to figure out is what info this array is giving the ecu about the throttle's position, and how it interprets that information and drives the motor in the throttle body, of course with dependency on throttle pos. input.

Does anyone have a service manual with this kind of info, or anyone/anywere to go for info on this system?

 

hey hey cool, i am the president of SAE in my school, good to hear your involved in it, good stuf

 

Why not make the mechanical roller that the cable goes around to open the throttle elliptical?

GM has done that for years, but the other way. The first 25% is 50% of throttle travel.

 

Yeah I know, keep it simple. That's why I'm trying to do some research on it, so that I may gauge the usefulness and feasibility of the idea. These cars are really fast and the throttle can be super sensitive. We've used cam throttle sprockets before. As a matter of a fact, I was thinking about milling one out for my car, since it's a torqueless beast that would much benefit from a more linear power-to-throttle. It might be pretty sweet to have a DBW setup on the racecar and perhaps be able to adjust the throttle curve on the fly.

I'm not all that familiar with the system yet, but we're using Haltec fuel management.

 

I found out today what the real problem is. The rule book (80 freakin pages) requires a 20mm restrictor on the 600cc GSX-R motor we're using. The throttle body is about 3 times that size, I'd say 60 maybe 70mm. SO the throttle body flows waaay too much air and it's useful working range is from like 0-15% throttle. The restrictor caps the motor at about 10,500rpm. I also believe that DBW is prohibited in the rules, but hey, I'm gonna hold on to this thing for whenever I get a cycle-powered road rocket of my own.

if I ever come across another running Audi, I'm gonna probe it