vems trigger problems on aan

[diesel des]

Yea there are some trigger faults shown in vems when cold. Then vems thinks its ok when warm with no indicated trigger errors shown.. more testing required I thinks

[a4kquattro]

Thanks guys, I'm going to try more testing with the scope tonight to confirm the pulses. And also try 58 teeth timing. Basically at the moment the car shows some small amount of triggering error on vems when cold. Then when warm vems shows no triggering faults on the screen but I get ping coming almost randomly when I shouldn't. I Think due to false triggering.
Eg afr at 0.82 at 3k rpm boost 1 bar and timing 9 deg advance. That shouldnt ping should it. Cheers des

there is a difference between trigger error and trigger OFFSET. ping can be caused by a trigger offset if the timing should make sense for the given boost. if vemstune/megatune is reporting trigger ERROR, thats a different problem.

[diesel des]

Thanks guys, I'm going to try more testing with the scope tonight to confirm the pulses. And also try 58 teeth timing. Basically at the moment the car shows some small amount of triggering error on vems when cold. Then when warm vems shows no triggering faults on the screen but I get ping coming almost randomly when I shouldn't. I Think due to false triggering.
Eg afr at 0.82 at 3k rpm boost 1 bar and timing 9 deg advance. That shouldnt ping should it. Cheers des

[a4kquattro]

CAM sensor signal is at pin 2 - should be 5V except during the window when it is low (0V).

If the VEMS gurus cannot filter out your rogue pulses I will have a look into for a small cheap box that eliminates... There is plenty of help I can call on from some fantastic analog electronics engineers if I get stuck.

Something like this might be a good starting point. All you need is an opamp and couple resistors/pots which can be used as the gate control for the G4 signal - preventing these low amplitude pulses from getting into the VEMS unit.

http://en.wikipedia.org/wiki/Thresho...ith_hysteresis

as I mentioned to Des before, he must get the details of the filtering resistors used in his ECU on the primary and secondary trigger inputs. whoever he ordered the ECU from should have spec'd this at the time of the order.

[S2central.net]

CAM sensor signal is at pin 2 - should be 5V except during the window when it is low (0V).

If the VEMS gurus cannot filter out your rogue pulses I will have a look into for a small cheap box that eliminates... There is plenty of help I can call on from some fantastic analog electronics engineers if I get stuck.

Something like this might be a good starting point. All you need is an opamp and couple resistors/pots which can be used as the gate control for the G4 signal - preventing these low amplitude pulses from getting into the VEMS unit.

http://en.wikipedia.org/wiki/Threshold_detector_with_hysteresis

[newsh]

"inverted" might be a bad term for it, but its what the vems guys call it.

VEMS has two trigger inputs, so the function of the hall inverter is to tie a transistor to the hall sensor that basically prevents the reference pin from sending a signal to the secondary input channel unless the hall sensor is in-window. This is critical on the 7a flywheel due to the large extrusions on the flywheel that show up as triggers without the hall transistor in place.

This absolutely makes loads of sense, I would say that "gated" would be a better term than inverted though.

[diesel des]

I'm thinking if I put my scope ground on the 5 v sensor supply by mistake with dc coupling input the signal would look inverted. Must test this tommorow.

[a4kquattro]

If vems is plug and play then why is hall cam signal inverted ?

"inverted" might be a bad term for it, but its what the vems guys call it.

VEMS has two trigger inputs, so the function of the hall inverter is to tie a transistor to the hall sensor that basically prevents the reference pin from sending a signal to the secondary input channel unless the hall sensor is in-window. This is critical on the 7a flywheel due to the large extrusions on the flywheel that show up as triggers without the hall transistor in place.

[diesel des]

Ok just checked, my cam signal is inverted compared to everyone else's! Wtf . What pins or wire colours were you on Paul on the cam sensor. Think I need to retest tomorrow night.

[diesel des]

Paul, it seems that it is to do with filtering. On the wiki page the guys are saying that the cam sensor output is normally high and drops low during its window. This seems the opposite to what we have found. But they say it needs inverted to go high and maybe enable the waiting for the crank pin. But why are our outputs already high during the window. There is nothing weird or inverted in the scope is there. Maybe I need to remove the inverter in the vems.

[diesel des]

Found a picture of the 7a flywheel and clutch setup. Clutch i got from Marc and is gooood...
I welded the extra steel on the pin after these pictures.

[S2central.net]

If vems is plug and play then why is hall cam signal inverted ?

[diesel des]

This is great feedback guys. Ok Marc, yea both the vems ecu's have the cam invert BUT on the wiki page the guys are now saying that it might cause a problem. What ya think??

http://www.vems.hu/wiki/index.php?action=edit&page=MembersPage%2FDesmondAudi

Paul, yea im sure the input could be processed to help vems out, but thats yet another box of bits which i could do without. And vems is ment to be a simple plug in setup, even with the 7a flywheel, so i think the software can be sorted to deal with this.

Jamo, thats interesting about the teath setup. I will ask Peter my supplier to confirm. Also will check about the injectors.

Cheers guys.

[a4kquattro]

Ok so now my car runs on VEMS but gets some trigger faults causing PING in engine. Look at the scope. Blue is crank pin, yellow the cam. The 7A flywheel gives 2 small extra pulses before and after the main crank pulse confusing vems.

and you have a cam hall inverter? You'll get extra pulses without one for sure.

[A80Avant]

Des, if it makes a difference, that pin looks definitelly bigger than the piece we made on my flywheel. BUT i cannot be sure if that could cause the problem, as this is something completelly new here.

i aggree about the trigger setting. Mine is set to 58 as well, although on older version (1.1.27)