InputTrigger/AudiTrigger

Page for the 135-tooth, 3-signal trigger system is the factory setup on many 5cyl audi engines - see "other triggers" chapter below for alternatives

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.


Maximum RPM for auditrigger is not 25500 RPM like for many other (mostly low toothcount) triggers, but still much higher than what the rods tolerate.


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.


Some (???) 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. (other toothcounts... See below)

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.

Earlier, some users applied 10+1 InputTrigger/MultiToothNoneMissing (5 evenly positioned crankpulse and 1 campulse).

If the factory wheel is in good condition, no modification is justified. Since 2010, with proper configuration VEMS v3 firmware supports >10000 RPM with the factory trigger system.

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

# rpmk=2400 (12000 / 5 cyl)
rpmk[0]=09
rpmk[1]=60
divider=01
# alternate=14 if you like batch firing during cranking
alternate=04
# coil type, NO filtering, bit6=1 auditrigger=enabled
# 1.1.23 requires bit6=1 (while 1.1.22 does not care, can work with primary_trigger=03 or primary_trigger=43)
primary_trigger=43
secondary_trigger=19
# yes, not 87(decimal 135) but decimal 90 !!!
tooth_wheel=5A

# 54/3=18
another_trigger_tooth=12
crank_minper=33
# with divide-by-3, we have 135/3=45 per crankrot that is 8 degrees, 32 * 0.25 degrees
tooth_wheel_twidth1=20
tooth_wheel_twidth2=00
cam_sync_r_edge_phase=00
cam_sync_f_edge_phase=00
reset_engphase_after=40
# PLEASE ADJUST _YOUR_ BASE TIMING! use trigger_tooth=00
# trigger_tooth: must be min 00, max 11 (decimal 0 to 17), somewhere in the middle should be fine, eg. 09
# sync from the edge at 134 BTDC cyl5, with 1.1.22 
# trigger_tooth=09 without cam-HALL inverter. trigger_tooth=00 with cam-HALL inverter:
trigger_tooth=00
ign_tdcdelay=74
ign_out=70
ignchmax=04

Find full config and trigger-extract at:

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

Only get information for starting, tune your engine


Other triggers for 5 cyl engines:

Some primary trigger patterns for 5 cyl engines. Spark is timed from crank, but 1 pulse CAM-HALL is needed (secondary trigger) in any case (needed for any odd-cylinder count engines anyway):

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 HALL trigger in the distributor. No crank trigger.

If a few degrees of ignition inaccuracy (due to cam-belt) is acceptable one of these distributors can replace the entire ignition system on the computer controlled cars. This was used with 1.0.x firmware (coiltype, tooth_wheel=5) and could be made to work with 1.1.6x firmware (a bit more variables there, yell if you really need that) but is hardly used nowadays, because of the plurality of the more precise "timed-from-crank" alternatives above.

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


See also: