Microsquirt Experience

[Beev]

Hello,

So I gave up on the noisy Dizzy and went with a 36-1 wheel but am struggling to get the car to start. I posted on the megaquirt forum but am not getting the feedback I was hoping for. If someone familiar with a microsquirted L20b an help would be appreciated.

http://www.msextra.com/forums/viewtopic ... 01&t=72787

Thanks

[icehouse]

I replied on Ratsun as well. Maybe Rob will disagree with me. I've Megasquirted 3 L series engines. I hate the 36-1 wheels, they get such a shit signal. I think you have your coils flipped. Swap them and see if it lights.

[Beev]

Thanks, I wasn't sure if it is 100% overlap or not. I have also responded on ratsun.

[510rob]

5.2 Crank and Cam tach inputs (page 45)
The tach input is one of the most important signals going into the Microsquirt and correct system operation is notpossible until the tach input is correctly installed and configured. Until the Microsquirt reads the correct RPM,nothing else will work.

In your MS post, someone mentioned that you have an inconsistent pulse train, so it sounds like you need to sort out the grounding and polarity of the VR stuff. The devil is in the details with this stuff.

Grounds

Make sure the grounds are correct. When running the grounds on MicroSquirt® EFI controller, it is important to remember that there are different "types" of grounds. These are:
1...
2...
3. VR return ground (Ampseal pin 33) - there is a separate VR(-) input on the AMPSEAL, this needs to be connected to the VR sensor(s). If you are using two VR sensors, return both back to this wire (these are low current and can be shared on the one wire return path) Do not ground the VR sensor anywhere else, return the ground back to the VR(-) terminal. On the MicroSquirt® EFI controller, this return goes directly back to the VR input circuit's transistor/op amp and not to the ground plane, this keeps the high amplitude VR voltages (and resulting currents) isolated to the VR circuit.
4...

With the small size of MicroSquirt® EFI controller, keeping the grounds straight is important. It is not hard, just keep things in logical groups - high power stuff goes to engine block, sensors on their own ground loop, and the VR sensor is also separate. The ignition coil current path is from the battery to the ignition coil to the MicroSquirt® driver and back. The same goes on for the injector and general purpose outputs. Lots of juice flowing on this path, it needs to stay away from the sensors. It also needs a low resistance/inductance loop. The Vref is the reference voltage generated by MicroSquirt® EFI controller, it passes thru the sensors and the return ground path comes back to the MicroSquirt. Only one return path is required for the sensors because it is comparatively low current, and we all know that voltage drop across a wire is driven by Ohm's law (V=I*R).

VRin: This circuit is designed for use with alternating current variable reluctor AC signals that have both positive and negative voltage components. For more info, see the ignition pickup page. This circuit has two sensor connections:

VRIN+ (coax cable center wire) on pin 32, and
VRIN- (coax cable shield) on pin 33.

(Some older diagrams may show these reversed - the text here is correct! It is also possible that some early production MicroSquirt®'s were mis-wired from the factory. Check the coax cable against the Ampseal pins to verify yours are correct: shield to pin 33, center wire to pin 32. If they are backwards, you do not need to swap them, just use the appropriate pins, i.e. the shield for the input (pin 32), the center wire for the ground (pin 33). If you prefer, you can swap the coax pins to be 'correct'. It takes 3 minutes to do. All you have to do is pull off the red clip on the harness connector, this will expose all of the pins. Next, find the two pins for the coax shield (pin 32 if it is backwards) and center conductor (pin 33) and *gently* wiggle them while gently pushing the terminal - it will dislodge and push back. then switch the locations and push back in till it clicks in place. Then reinstall the red clip (line up all of the terminals).)

this is related more to the non micro-versions of MS, but gives some insight as to what to look for when using the tooth logger...

https://www.diyautotune.com/support/tec ... squirt-vr/

Also, if you look at page 3 of the schematics, there does not appear to be any ability to adjust the VR signal conditioner...

http://www.msextra.com/doc/general/pix/ ... rt_2_0.pdf

[Beev]

Found the issue. There was a software filter on and it was filtering out teeth for the 36-1 wheel. Thanks for the suggestions. Now to tune and ask about ignition tables (in another post)

[Byron510]

Ignition table as I used on the Bronze as sent in a text to you - here for all. 2.2L with programmed rev limiter...

RPM -Degrees advanced

0-1499 12
1500 15
1750 20
2000 25
2250 30
2500 32
2750 33
3000 35
3250-6750 35
7000 20
7250 10
7500 - 9000 0