Primary Trigger Problem

The problems I am having with the primary trigger is twofold. On one side, the VR sensor in the factory setup reacts to a tooth that's only 0.3mm lower than the other teeth. VEMS has very good noise suppression, it neglects noise that can be up to 50% of the signal amplitude (never happens with a proper wheel). VEMS HW noise suppression can be made poorer with higher R181, replace R181=150k with R181=270k or so.

On top of that, it turns out that the wheel has 145 teeth, not the previously supposed 72. Simplest to install 3 bolts and a HALL sensor (4-1 setup).

The TDC sensor signal was checked with a scope and now looks very neat. My configuration concern is how to setup the VEMS to deal with the 36-1 trigger wheel on the camshaft (one tooth is 20 crankdegrees. We have one event every 9th tooth). It allows setting up for sequential injection of course. Ignition will still be wasted spark for starters. Almost like a standard 36-1 (number of wheel on teeth is like that: 35), but some variables resemble a 18-1 setup.

The last 3 variables make no difference with 1.0.x firmware.

I'm als unclear on what the modification values for the rpm in megatune are supposed to do, or what they relate to. I would expect a multiplier there, not a number in the hundreds or thousands. Essentially, in one trigger wheel revolution I want 4 injector events (one per injector) and 4 ignition events (2 per ignition module).

At the moment, the primary trigger now works flawlessly without any errors. In the end it's a 12-1 4mm thick wheel on the camshaft, detected by a HALL 1GT101DC sensor for which we had to resolder the VEMS. But that all works perfectly now. On to other issues.


I have rebuilt an engine for my car, and I am working with an electro-optical Hengstler RI32 encoder. It gives 100 push-pull pulses per revolution on one channel, and 1 push-pull pulse on another.

Problem is, obviously, that cam sync assumes a 200+1 setup, not a 200+2. I have a working RPM signal now, by pretending it's a 100+1 setup, but my rpm is therefore 2x as high as it should be, and I keep getting a sec trig pos bad error even with the min and max set to 1 and 360.

Any suggestions most appreciated. It's still the same 2.5 liter side-cam 4 cylinder engine setup, it's just that PT is now on the crankshaft using the electro-optical hengstler encoder.