Megasquirt users thread to discuss all things Squirty

[thechuckster]

just use both factory VR sensors. JBPerf sells a great dual VR interface board/kit that works just fine with denso VR sensors.

[old_mr2]

Already tried that mate, couldnt get an rpm signal below about 1500rpms....

[Harreh]

Just buy a damned CAS/SP Dizzy and be done with it

[drew22]

Already tried that mate, couldnt get an rpm signal below about 1500rpms....

Have you thought about using a HEI modual to condition the VR signal?

[old_mr2]

Hi Drew, I dont know about the HEI module, I wil look into it

[thechuckster]

fwiw: poor signal levels from denso VR sensors can come from the air-gap being too large. My old setup (22RE reluctor with 4-tooth ring) used the LM1815 interface and gave solid signals from cranking and above revs. Interference (indicated usually by false triggering) comes mostly from poor earthing/shielding.

[old_mr2]

I tried altering the air gap, but no luck, same results. ToyoAl is having great success with his modded dizzy hence me being interrested in copying... I also tried shielded speaker cable, but still could not read at low rpm


Harreh, Im not sure if it will work? SP/CAS, plus I would have to source one!

[oldcorollas]

is the PCB set up correctly? haven't left a resistor or added something that aint needed to read from the VR?

[knightrous]

Have you looked at adjusting the VR voltage threshold?

From the DIYPNP site: DIYPNP Documentation - DIYAutoTune.com

Variable reluctor sensors, sometimes called VR sensors, inductive pickups, or magnetic pickups, have two wires, and possibly a third shield wire. Connect the positive wire to VR+ and the negative wire to VR-. Sometimes it may take a bit of trial and error to find out which is which since factory wiring diagrams often do not mark these clearly. If you have a shield wire, connect it to GND. Tip: If your sensor is connected to a wheel with a large number of teeth, like a Ford 36-1 or a Bosch 60-2, and you're losing the tach signal at high RPM, put a 10K resistor in line with the wire going to VR+. This will usually clear things right up.

The camshaft position sensor input is marked VR2. It's actually a kind of hybrid circuit that works with Hall effect, VR, and optical sensors. Hall or optical sensors may need a pull up, just like with the crankshaft position input. VR sensors with a separate ground wire should have this wire connected to SG. The VR2 circuit has a built in threshold that some VR sensors may not trigger correctly at low RPM. If this happens on your car, take a 51K resistor and install it in the R21 position. This will lower the threshold voltage. Many Nippondenso ignitions will need this mod. For other sensors, you can install R39 to make the trigger voltage user-adjustable, or use R20 to pull up the trigger voltage to reduce noise.

I've installed the R39 trim pot in my DIYPNP for the 20V, hopefully this week I'll have finished the extra bits of wiring and can start cranking it over to see how the 24-1 dizzy works for me.

[old_mr2]

Thanks Knighttrous, I must have missed that in the documentation! I am not running that resistor, hopefully it will clear my issue right up.

[knightrous]

Having a similar issue with my DIYPNP with the 24-1 Dizzy, I'm getting 0 RPM in Tunerstudio, but firing up the composite logger while cranking and I can see the teeth being detected. Got a thread on MSExtra here: Megasquirt MSEXTRA / MS3EFI • DIYPNP v1.5 - 4AGE 20V Silvertop - No RPM (View topic) and fired an email off to DIYAutoTune.

Hoping it's just some silly resistor I've missed or a quick config I need to change to get it cracking. Other then that, the DIYPNP is a dream to work on, much easier then the MS2

[MWP]

With all this talk of VR issues... has anyone tried gutting a toyota VR sensor and converting it to hall?

[knightrous]

Gutting the dizzy has been done a fair bit with good results, but a lot of people would prefer to just use the factory items without modification. The biggest hurdle is understanding how the factory system conditions the VR sensors and gets them to work so well. You can plug the MS into these sensor and struggle to get them to work (Or they work perfectly first go), but plug the stock ecu in and it instantly works perfect, it's not a case of VR sensors being fiddly devices, it's just a lack of solid understanding on how to set them up correctly for the MS.

[knightrous]

Actually, having just seen this:
https://www.facebook.com/video/video...50428021423906

Hall sensor might be the way forward >.>

[knightrous]

If anyone is looking for a robust hall sensor, Element14 has the 1GT101DC for $26.81ea.
HONEYWELL S&C|1GT101DC|SENSOR, HALL EFFECT, GEAR TOOTH | element14 Australia

I ordered a pair yesterday @ 2PM (For when I rage quit on VR sensors) and they arrived at 10:30AM today. Might have to order a couple more to make a digital speedo for my V6 AW11.