Audi S2
This car is owned by a friend and I have been able to use it for some AudiTrigger testing. It has been a slow project as it's hard to allocate garage cycles.
It's a clean car with mostly handling and brake modifications but the 3B engine was recently upgraded with some RS2 parts and a slightly bigger then RS2 turbo. The car is used on the road and for trackdays.
Auditrigger testing 2007-03-09:
The more or less undocmunented 1.1.18 auditrigger configuration caused some trouble initially but it was solved after making some questions on IRC questions.
- The main difference is the lack of distributor support in 1.1.18, this means that ignchmax has to match the number of cylinders even on a distributor engine. So it's set to 4 instead of 0 in this case. The 4-0 channels then has to be set to the same output.
- The addition of overlapping dwell also cause some trouble as you currently have to limit the max dwell so it will never overlap in a distributor application. If it overlaps the output will stay on. I'm sure this will be fixed shortly as a distributor is a very common on high power engines.
- I didn't have time to fanny around when hearing that the H1 table previously had to start at 0, so I changed it at once and don't know if that was an issue in Kalske's configuration.
- There is still issues with this configuration, we ran out of battery and the timing light started resetting when cranking so we had to stop testing before we could get the base timing right. But we saw some strange behaviour, the timing was very late, approximately 45 deg ATDC, when changing trigger tooth to 10 instead of 27 the timing got even later?! When changing to 45 it stayed about the same... Is the trigger tooth used for something else in this application?
Auditrigger testing 2007-02-23:
Secondary trigger
Tested secondary trigger and found that even with C40 upgraded to 1.2uF it does not prevent false triggs during the last third of the rev. This was very clearly seen on the scope.
A weak pulldown of 2.7k was fitted (1k resistors not available during the test) and the mode jumper was used to connect pin 5 of the secondary trigger 1815 to 5v. This removed most of the magnetic noise from the speed sensor wheel and improved signal quality a lot.
Signal was still very strong and for the next test a 1k resistor will be used.
Primary trigger
I forgot about that I configured the pulse length for the output signal to be shorter on the primary trigger, this resulted in a scope setting that was to slow to reliably see all pulses. The pulselength is now ca 30us with R57=33k, R57 is normally 75k which will prevent high rpm operation with Auditrigger.
This had the benefit of me scoping most signals around the LM1815 chip. The signal on the adaptive thresold pin (pin7) was interesting:
Add pin7 scope plot here.
When charging the capacitor the current is pulsed, with R181=150k this results in a very strong sawtooth signal. For Auditrigger R181 is most likely not needed and I bridged it in this application. We need to review this to check if it can cause problems!!! An additional capacitor to even out the signal could improve performance.
So far the tests has been run with R56=18k (has to be changed to 10k), no pulldown (1k will be fitted, signal is VERY strong at cranking).
Ignition:
Something is wierd with the ignition output, possibly an inductive load somewhere on the wire to the ignition powerstage. I didn't have time to investigate in the middle of the night. It produced a 0.5v negative sharktooth instead of a 5.6v positive square pulse. Very tired...