Subpage of InTake/ThrottlePlates


This is a DBC (Drive by Cable) VAG throttle body used on VAG models, generally 1996 to early 1999.

Firmware implementation notes

ETC (electronic throttle) is implemented in VEMS v3 fw since 1.2.14

The PWM-ing frequency is actually 488 Hz, currently unconfigurable (usual recommendation is 450-550 Hz and throttle gets warm at low freq especially under 100 Hz).

When ordering assembled ECU, it is important to write Electronic Throttle output stage-box" in the order comment.

The above information and firmware is for DBW Drive By Wire throttle control.

The VAG Passive Throttle listed on this page IS NOT DBW.

It is only electronic idle motor to throttle plate, the actual full opening of the throttle plate is cable operated

I was thinking about this throttle: what makes it special that prevents using either the IAC-PWM or (since the IAC can also effect the ETC target) ETC code to drive this throttle...

Bridge-output is needed in any case so request "H-bridge for VAGpassivethrottle" in the order comment.

How it works

The 1996-1999 VAG DBC throttle body contains:

* Motor measures 4.0 Ohms at rest.



See [DBC circuit diagram].








Note that it has 2 speed-down gears inside, about 1/7 and 1/8 ratios (1/56 effectively).

NEW Kevin Information / Control Development:

1) Idle Control Issues:

I have tried to use an Injector Output to PWM to control for this (with IN4007 Diode), but the throttle plate movement is "weak".

For example, I can have it slightly open, and take my finger and physically move the plate, and it will not "self correct".

* Does power source matter? (Ignition Power vs. Power Connected Directly to Flyback Circuit?)

This translates to the engine speed fluctuates greatly, and proper control is impossible.

(I can pin idle control to fully open or fully closed OK, but everything in between is bad).

yes, because from the schematic it looks like +12V and -12V bidirectional drive is needed on the motor to move one direction or the other

2) Idle Switch Implementation (or temporary hack)

New Wish, please add "Accel Enrichment Trim" to Anytrim options, so I can disable (lower by 300%) the TPS enrichment when the (poorly controlled at 10-20HZ) throttle plate/tps is bouncing around. KevinBlack?

Sensor Info

Sensor Measurements (on Audi V6 unit)

Pins 5-7 (TPS and Sensor Ground)

Pins 8-7 (IAC-only TPS and Sensor Ground)

* Motor measures 4.0 Ohms at rest.

Wishlist Summation:

Advanced: the throttle-controller code would watch a 2nd analog input for throttle-command (I recommend TCS abbreviation, because throttle-pedal-sensor abbreviation would collide with throttle-position-sensor we already use)

  • decision is needed for connections. In any case, for internal idle-threshold the throttle-command (pedal sensor, not the actual throttleplate position sensor) must be used, for safety

Please measure current, and try to confirm that reverse driving voltage closes it (try to be careful, and use fuses).

* TODO - Figure out proper Testing Method.

* Motor measures 4.0 Ohms at rest.

* Reverse voltage does close throttle completely.

Jorgen's comments :

There can be different versions of this throttle, but the ones I have seen worked fine.

as soon as the idle control is activated the TPS will change, and the idle control will be turned off instantly after hitting Vems TPS Threshold setting.

There is an idle switch in the throttle, you need to use that to short the TPS signal to ground.

Possible interference with TPS-acceleration enrichment

There will be a sudden jump in TPS voltage when the idle switch become inactive as the TPS signal go from 0v to the output of the TPS instantly. I have expected this to give a squirt of fuel through the acc enrich but I have not tuned any of these cars myself and the customers who did the tuning didn't notice a problem even if I asked them to look for the problem. I'm sure that we can come up with a workaround if it's needed.

But it would obviously be best if we could have an idle signal input on the ECU.

Plan - steps

We need to find out

  1. hardware requirements, like current consumption in both direction (when moving, and likely higher when stopped)
  2. if the +-12V drive assumption is correct
  3. voltage mapping of the analog feedback signals for min 8 points, and min 4 points around idle
  4. implement firmware code for it
  5. find/tune suitable PID parameters
  6. write some vemstune help text for the new dialog

(OLD info, should update) Sources

Costs > 350 Euro. Anyone knows good sources ?
  • Audi V6 uses much larger (~70mm plate) size with same design
  • Audi PN 078-133-063AP

Pre-1996 VW TPS Info(Should be moved)

See also