InputTrigger/AudiTrigger (2008-12-13 22:36:45)

Page for the 135-tooth, 3-signal trigger system found on many 5cyl audi engines

The GenBoard/VerThree trigger hardware supports the Audi 3 input signal system since v3.3:

The first successful install with this trigger-setup was done by Miska Peippo in Finland in 2005, see MembersPage/MiskaPeippo/AudiSSix.


Cam-HALL inverter

Cam-HALL signal is used to mask one of the 2 crankhome pulses.

For [Audi 7A flywheel] that has strange notches that disturb the crankhome-VR signal, an inverter is needed to neglect the big window around 134deg BTDC cyl5 (and keep the small window around 62 BTDC cyl1).

The inverter can be an NPN transistor such as TIP31

If you have an Audi 7A flywheel, be sure to mention it to your dealer when ordering. Cam-HALL inverter is essential for 7A flywheel, and recommended for all installs.


Internal trigger hardware setup

See InputTrigger/AudiTrigger/OldHardware for older information.

v3.x since 2008-07


Overview: multitooth Audi crankwheels

The old Five cylinder engines with electronically controlled ignition have 2 VR sensors and a HALL sender.

These engines use a homebrew ignition module with a visible TO-3 transistor in the ignition coil console. (at least the ones I have seen) Igniton computer is made by Hitachi (MAC-xx).

The small spacing between the teeth (together with cambelt sloppyness) makes it impossible (at least without very advanced, long-term filtering) to sync the engine without the pin in the flywheel.

Signal timing graph from 5-cylinder MC-engine:

audi_mc_trigger.gif

The same type of triggersystem is used on many older Audis, even the Audi V8 had it until it was replaced with the A8. The engines with an even number of cylinders has an 136teeth flywheel to make everything add up.

Solution:

The cam-HALL pulse (0 volt) masks out the 62deg BTDC cyl1 crankhome pulse, but (high level, usually 3.3 .. +5V) leaves the 134deg BTDC cyl5 pulse reach the processor. (just the other way around with the cam-HALL inverter)

This way the processed "cramhome" signal is timed from crank, but only 1 pulse for each cam-rotation''' (suitable for 5cyl ign). Effectively a 'cam ref signal' with no slop at all.

135 interrupts per crank-rotation still needed, but the interrupt code is shorter than for 60-2 wheels, allowing 9000+ RPM.

Above 9000 RPM most users apply 10+1 InputTrigger/MultiToothNoneMissing (5 evenly positioned crankpulse and 1 campulse). 15-1 style missing tooth crankwheel was also successfully used, but 5 evenly positioned crankpulse is simpler. The only disadvantage of 5*72 degree crankwheel is that camHALL chosen edge must clear the crankpulse even with the worst case of cambelt sloppiness (ideally midway between the neighbor crankpulses, 36 degrees from each). With 15-1 wheel just make sure campulse stays away from the tooth after the missing cranktooth.


How to connect the 3 trigger signals

Don't forget to use shielded cables, separate for all 3 signals. The shield only connected at the ECM end. "return" is to GND (sensor ground), not GND5. See MembersPage/PhatBob/UserGuide.

See InputTrigger/AudiTrigger/TestLM to see how the first installs got sorted out. Old method, likely will not work with 1.1.x, should not be needed anyway:


Signal Sloppyness - info for advanced users. Safe to skip

The sloppiness seems small, see [image1] and [image2]. Our implementation accepts if the "cramhome" (== crank-cam hybrid) pulse comes normally, or one tooth too early (which should be rare, but possible if the VR sensor is not aligned properly).

If the crank-home is sloppy, not always between 2 given crankteeth, the code will finally sync as if the crank-home always came after the tooth coming later.

Example

Here we name 3 given teeth A,B,C. If crankhome is seen


HISTORICAL configuration for 1.0.x (for 1.1.23+ is the official branch for auditrigger now, this is obsolete)

We must start from a coiltype + camsync setup (maybe like MembersPage/MichaelRichards/Projects/NicksGTX or [Fero]

Auditrigger 135 tooth config for 1.1.22+ :

http://vems.hu/download/v3/firmware/v3_firmware_1.1.22.zip\nÿ1ÿ

Find full config and trigger-extract at:

http://vems.hu/files/MembersPage/MarcellGal/Audi/etc/

Only get information for starting, tune your engine


Other Audi triggers:

There is also an other audi trigger arrangement on the older audis that don't have a knock sensing ignition. They only have a 5 slot trigger wheel in the distributor and no crank trigger and a hall sender controlling a auto dwell ignition module. If a few degrees of ignition inaccuracy is acceptable one of these distributors can replace the entire ignition system on the computer controlled cars.

The later models have a standard Motronic triggerwheel and a CAM sync sensor.


See also: