Dual tach input

[feak1]

For the tachRef i showed at the begining of this post:

stock VR1 sensor+ to MS VR1+
stock VR1 sensor- to MS VR1-

stock VR2 sensor+ to MS VR2+
stock VR2 sensor- to MS VR2-

**note :stock VR connector was unplugged from the TCI unit.


For the latest tachRef :

VR1+ from MS and VR2+ from MS are left floating

stock VR1 sensor- to MS VR1-

stock VR2 sensor- to MS VR2-

** note : i had no rpm reading on tunerstudio unless i connected back the stock VR connector to the TCI unit.


I did a couple of test today but didnt make any progress

[dontz125]

Ok, I did mention an edge detection circuit, not just wiring the sensors directly to the uS ...

Try this:
Sensor 1+ to diode (band towards uS) to VR1-
Sensor 1- to diode (band away from uS) to power GND

Sensor 2+ to diode (band towards uS) to VR2-
Sensor 2- to diode (band away from uS) to power GND

Any rectifier diode with a rating over 100v will do; I might suggest Schottky as a high Vf might absorb the signal at cranking.

[feak1]

i ll try that tomorrow but what do you mean by "power GND"?

[dontz125]

Some of the pins are labelled "Power GND"; there is also "Sensor GND" and "Serial GND." Just rechecking the schematic, all the ground pins are tied together at the circuit board, so it doesn't particularly matter.

[feak1]

ok thanks !!

heres a pic of my VR1 wiring:

VRWiring.png

(567.82 KiB) Not downloaded yet

I used 1N4004 diodes which are rated for 400V i believe.

SO in the morning i wired up like this , only using VR1 and check the tachRef which gave me a nice reading , i tried it twice and worked great.

I was very happy and felt excited but...

then i wired VR2 the same way and checked the tachRef but it didnt gave me any reading at all not even for VR1.

So i disconnected VR2 to check back at VR1 signal on tachRef, nothing came out, no readings at all.

i know sometimes i forget the boothloader connected to ground after loading code and tachRef wont work but in this case boothloader cable was floating when i tried VR1.

Checked my wiring and diodes with a multimeter and everything looks OK.

Checked MS VR1 and MS VR2 circuit and they work.

So i dont know why it worked twice this morning and got nothing after that, didnt have time to print screen the tachRef to show you the new signal

i dont know if tachRef is playing me some tricks but i ll run some more test tomorrow , battery had a long day and needs charging.

i ll keep you updated thanks for your help!!

[feak1]

Update :

ok so now i got a signal like this on tachRef

TachRef.png (5.08 KiB) Viewed 3485 times

Why cant tachRef see the 180 deg offset that seperates both signal like i see in my oscilloscope?
I mean in the picture they dont look like they are separate equally like an even-fire would be...

[dontz125]

Looking at your pic, the wiring is incorrect. The uS pin VR1+ is not used. The +ve side of the VR sensor goes to uS pin VR1- (diode band towards the uS); the -ve side of the VR sensor goes to uS GND (diode band AWAY from the uS).

[feak1]

i tried different variation including what you told me to which is exemple #2 on this picture.

FZX_TachRef.png

(173.22 KiB) Not downloaded yet

on exemple #2 , vr2 was connected too but signal didnt show up on tachRef thats why it only shows one signal.

Still no offset showing in tachRef , but i guess that its how tachRef works...

[feak1]

ok im starting to get good results here but there is so much confusion about my understanding of the manual and how MS handles spark calculations for my setup.

1- Since in dual tach input mode M = 0 :

-how does MS knows the engine position and fire at an accurate position if there is only one teeth? Does it calculate it based on "Time since last teeth"?

- how can trigger offset be applied if M = 0 ?

- What about cranking trigger mode "Calculated" or auto-trigger ? How does MS handles that if M = 0?

- how does MS knows when to start charging the coils?