MembersPage/FPhil/SomeOddFireConcerns (2015-01-20 10:46:34)

I shall report here some of the problems I had while configuring the parameters (odd-fire, low toothcount maserati VR / VR trigger engine).

Related to [this report]

For a reasonable setup like a 60-2 a missing or an extra primtrig pulse does not cause serious out of sync usually. For a low toothcount setup (which is a bad idea in general, and especially bad idea if it's not HALL but VR), the trigger pattern should be high quality signal (it would be interesting to see why the lights effect it, maybe grounding can be improved ?).

So the options are:

Switching on lights influencing trigger is almost certainly a grounding problem somewhere. Getting out of sync with a lost primtrig pulse (especially for a low toothcount setup) is not a firmware problem. The install wiring (and perhaps VR sensor bias pullup resistor?) should be reviewed and fixed so that the VR signal is sufficient quality and turning on lights should not cause lost pulses or noise pulses: than the engine will stay in sync.


Missing primtrig pulse in the case of the coil type trig setup

I was steadily driving at 60km/h entering a tunnel in a busy trafic. At the time I switched on the lights the engine shakened badly, made big noise, big smoke behind the car, seemed to have no more power.The engine stopped when clutching off. Then the engine restarted ok when clutching on by the car still moving on.

At my parking slot, I was able to record the trigger log of what may has happened the night before.

Switching on and off the car lights, I noticed that sometimes the engine was accelerating or slowing or eventually may stop.

Here is trigger log when the engine stops. (prim trigs are 30°, 90°, 30° apart, there are 3x2 pulses on the crank wheel). One can see that Vems came out of sync but was still firing.

outofsync.jpg

Here is the same log without the fire events.

config2trigmissing.jpg

It shows that one prim trig is missing (@ first complete revolution).

Indeed, to further what the Vems support has told me, with a reasonable setup like a 60-2 an extra trigger pulse or a missing pulse does not cause serious out of sync. However for a low tooth count setup such as coil type, the trigger pattern can have a high quality signal, (I scoped mine several times before), but comes to get a default, per ex. because a ground problem occurs (one does not install a non oem ecu on a new car).

I believe that an operational software should detect those trig errors and takes proper action: This does not seem to be a big fw update to check if the incoming pulse is in a good window or not, and, if it is not the case, do re-sync (per example)

At least, Vems should let people know that there is no trig error management with the coil type set up and that there is some risk of engine damage or car crash in a tunnel incoming Paris ;p)