[SOLVED]: VTwin, VR Sensor, Noise

[afornwald]

Hi guys!
I need your help reading the crank vr signal:

1. Yamaha XVS 1100
a. VTwin
b. OddFire (75deg)
c. VR Sensor measures two long(!) teeth. A random noise of around 0-1.5V has been detected. This noise comes from alternator and starter. Alternator is situated very tight to VR Sensor.


2. Microsquirt V3.0
a. ms2extra3.3.4_alpha
b. twin trigger setup in wasted spark
c. source code modified in order to read from one crank sensor. TESTED

3. Readings@240rpm with stock 5kOm shunt + stock 10kOm VR+, VR- inline resistors. A lot of noise.


4. Readings@240rpm with 470 om shunt + 100kOm VR+, VR- inline resistors. Readings are good but I assume that max992x is reading around 10mV max on VR+, VR-. Is this ok?


I assume that MAX992x is not working in adaptive mode because there is a gap > 85ms at 240rpm. How can I filter this noise in order not to read such a weak signal 10mV? Is it ok? Is there any special tweaks?

Regards,
Andrei

[jsmcortina]

The long tooth is a problem. The MAX chip isn't designed to support that waveform.

James

[racingmini_mtl]

You could try disconnecting your sensor from VR- and grounding this; leave the VR- input not connected to anything.

That might work if the signal is always above 2.5V in amplitude.

Jean

[afornwald]

You could try disconnecting your sensor from VR- and grounding this; leave the VR- input not connected to anything.

That might work if the signal is always above 2.5V in amplitude.

Jean

You mean:
1. Connect one wire of VR Sensor to the ground
2. Connect the other wire of VR Sensor to the VR+ input of Microsquirt
2. Leave VR- input of Microsquirt unconnected

Did I understand you right?

[racingmini_mtl]

Yes.

And no need to PM me the exact same thing to get an answer from me. That may have the opposite effect.

Jean

[afornwald]

Last question. Do I need a shunt between VR+, VR-?

[racingmini_mtl]

Not if you just use VR+.

[speedy39]

Last question. Do I need a shunt between VR+, VR-?

What was the stock setup? What was or is the tab on the flywheel look like size ect. What year bike.

[afornwald]

Problem has been solved using instructions provided by Jean. Thank you very much!

Stock setup: Carburetor with CDI. Model Yamaha XVS1100A, 2004 year.
Flywheel with long teeth looks like:

[speedy39]

Problem has been solved using instructions provided by Jean. Thank you very much!

Stock setup: Carburetor with CDI. Model Yamaha XVS1100A, 2004 year.
Flywheel with long teeth looks like:

Ok, so stock you have two flywheel tabs and one pickup?

[afornwald]

Ok, so stock you have two flywheel tabs and one pickup?

That is right.

[feck]

I had been searching for a solution to the VR signal problems we've been having on a Kawasaki ZX10R engine with a Microsquirt ECU and this thread was the key to the answer!!

The set up is a standard engine using only the 24-2 crank trigger wheel and the oem VR pick up wired to VR1-In. It was starting and running well until we started working through the low load areas of the fuel table and found when we got to 7800rpm it would lose sync. We went through the manual and searched the forums coming up with and trying: swapping the VR signal wires (no good), fitting a range of shunt resistors across the VR wires, the best of which helped a bit, but only got us up to 10000rpm. Fitting a 10k resistor in line with the VR1+ line didn't get any different results. I was going mad trying to work out what I must have done wrong before I came across this thread and thought we'd better try it. Snipping the VR- and connecting the sensor -ve to the sensor ground allowed it to run, but had sync loss at 8000rpm. Fitting a 680 ohm shunt resistor again suddenly let us rev to the current rev limit of 13500rpm with no sync loss. Success.

Hopefully this helps anyone else who might be trying to work through a similar challenge. More often than not I've had little to no success with the Megasquirts I've installed with VR sensors and in most cases have only been able to fix the problems by fitting a hall sensor instead. Hopefully this is the first exception to that rule.