Forum thread on www.vemssupport.com : http://www.vemssupport.com/forum/index.php/topic,2248.0.html
Engine setup:
- V12 with ITBs and turbo
Sensor/setup
- 6 teeth on crank
- 1 tooth on cam
Problem
The issue with 12 cylinders and this trigger setup is that you require 12 actual events to be defined between cam sync pulses. One for each crank tooth. The trigger reference tooth table is limited to 8 cylinders.
I have previously asked for a more flexible solution for 10 cylinder engines as well.
Simple solution would be :
- Increase length of trigger ref tooth table
- Or allow the trigger logic to accept cam sync every other crank revolution and still use only 6 rows of the ref tooth and ignition output table. Wasted spark (even fire) engines only.
A: If its an even fire v12, the coils can easily be wired in pairs (as well as injectors). Therefore 6 only 6 cells would be needed in reftooth table - DB.
Q: This is not my car or my project, it is many 1000 kms away. I will try to help him. He can not change the trigger wheels. The fact that it can be set up as wasted spark is no surprise to me - the point of this page is that we know it can be, but the trigger setup does not agree. or does it? Here is how I would try to do it, VemsTune complains about setting this up :
- Number of teeth of full engine cycle : 12
- Setting to 6 and it does not complain
- Next trigger tooth : 1
- Ref tooth table : 0,1,2,3,4,5
It would be nice if someone could simulate and check that both revolutions of the crank get spark and fuel, not only the first. If the firmware logic expects to see 6 teeth and then camsync, and doesn't until 6 more teeth have passed, will that just cause trigger errors?
If what you're saying is true a 4 cylinder engine with 2 teeth on the crank and 1 pulse cam sync should be able to run with wasted spark by defining only two rows in the ignition output table and trigger reference tooth table.
- Number of teeth of full engine cycle : 2, 4 ?
- Next trigger tooth : 1
- Ref tooth table : 0,1
Will the firmware automatically understand that the cycle repeats twice or throw trigger errors?
Avoid primary trigger settings visual dialog, it can sometimes wreak havoc with the settings when you try things outside what it knows, so open the dialog carefully.
Hello Mattias,
Suggested setup, VemsTune complains but accepts it (indeed don't use trigger settings visual for this cheated setup).
- Number of teeth of full engine cycle : 6
- Number of cylinders: 12
- Next trigger tooth : 1
- Ref tooth table : 0,1,2,3,4,5
- Cam sync enabled.
- Number of ignition outputs: 6
- Number of injector outputs: 6
I have verified this on bench but indeed found some problems with the automatic reset when camsync is missed.
These have been corrected. It now works correctly but complains about missing secondary trigger in second phase (which is correct) but will otherwise run fine.
These changes will be included in the upcoming 1.2.27 firmware release.
This will also enable:
a 4 cylinder engine with 2 teeth on the crank and 1 pulse cam sync to run with wasted spark by defining only two rows in the ignition output table and trigger reference tooth table
Number of teeth of full engine cycle : 2
Next trigger tooth : 1
Ref tooth table : 0,1
I hope this helps you and your customer out.
Best regards, Dave (DB)