MicroSquirt.com read only forum (Jan.15,2018)

We aren't getting any RPM reading. We've spent hours reading everything we can trying to troubleshoot the problem. We are running a Honda 600 F3 with fuel injection.
This is what we know right now:
1. Microsquirt connects to computer and receives readings from all sensors except the VR sensor
2. we are running a trigger wheel with 12-1 tooth
3. we tested our VR on the oscilloscope and we are getting roughly 1V while cranking
4. we ran the "tach signal analyzer" program and are not getting any readings
5. we are not getting any spark(obviously cause we have no RPM reading to MS)
5. fuel injectors are not spraying(suppose that's depends on the RPM's too)

VR has a red wire, black wire, and shielding
We wired the VR up to the MS harness as:
VRIN1+
red wire to coaxial center wire(harness)
black wire and shielding to coaxial shielding(harness)

We are new to MS and tuning and can't figure it out. Anyone willing to provide us with a tech-line? haha
Any help is much appreciated!!!!! Thank you!

uofu_fsae wrote:3. we tested our VR on the oscilloscope and we are getting roughly 1V while cranking

VR1IN+ is normally OK, so you probably have too much noise on the system, there will be some interference stopping the MicroSquirt seeing the teeth.

Have you tried taking the plugs out and cranking the engine? to see if the VR on the oscilloscope is cleaner or has higher peak to peak voltages.
If this improves things you might benefit from tweaking the air gap closer, as this should raise peak to peak voltages, and help at the slower cranking speeds with the plugs in.

12-1 should work fine, so frustrating though it is, it'll be something simple, but you are applying the right approach, by using TachRef analyser and checking your VR signal with an oscilloscope. Once you have a TachRef trace with a missing tooth gap, you should get sparks. Don't forget to calibrate your TPS, as you might have a default value for the throttle that is high, and puts the MicroSquirt in "flood clear mode", and obviously this stops the fuel flowing.

Still getting nothing

Since we are so new to this, maybe someone could help us with some basic ignition settings??

uofu_fsae wrote: maybe someone could help us with some basic ignition settings??

If you post your msq, it'll be easier for others to look at it. t.

So I've added our msq file. Again we are very new to this, so I'm hoping one of you knowledgeable pros can easily find our newbie mistake. We have been somewhat frustrated when trying to read-up on the MicroSquirt. Many times we don't know if something corresponds the the MicroSquirt or only the MegaSquirt. In fact, we read on the MegaManual that you need to "select the tach input circuit with jumpers." There are instructions for the VR sensor or the Hall Effect sensor (which ever you choose to use). Does thisappy to the Microsquirt?????? (step 51 and 52 for assembling the megasquirt board). Thanks for your help guys. Hopefully we can get this thing firing soon!!!!

Ok so today I finally got something out of that VR sensor. It came by 'accident' actually. I hooked up the oscilloscope to take a look at the signal again and forgot that I was still connected to the MicroSquirt with Megatune via my laptop. When I cranked the engine, I happened to look at my laptop and notice I was getting a reading on the RPM gauge. So why now? I found out that it liked the ground from the oscilloscope. But now it seems to be resetting ever time I crank (i hear the fuel pump cycle every time). So maybe a grounding issue?? All sensor grounds return to pin 20 on the MicroSquirt and not the chassis ground.

The VR sensor grounds go to pin 33, but either way, I looked at your msq and the first thing I noticed was the engine size was 350 cubic inches! So your fuelling may be a tad high.

24c wrote:The VR sensor grounds go to pin 33, but either way, I looked at your msq and the first thing I noticed was the engine size was 350 cubic inches! So your fuelling may be a tad high.

Ya actually I caught that one first thing today. And after thinking about the ground for a sec you are right, the shield grounds to pin 33. I was testing it for continuity to the board. I don't get what the problem is, but it wants another ground....... What do you guys/gals think?

So we got the engine sputtering and popping today. It really wants to start. I think a little more tuning with the ignition parameters and timing and hopefully it will be idling.

uofu_fsae wrote:Ok so today I finally got something out of that VR sensor. It came by 'accident' actually. I hooked up the oscilloscope to take a look at the signal again and forgot that I was still connected to the MicroSquirt with Megatune via my laptop. When I cranked the engine, I happened to look at my laptop and notice I was getting a reading on the RPM gauge. So why now? I found out that it liked the ground from the oscilloscope. But now it seems to be resetting ever time I crank (i hear the fuel pump cycle every time). So maybe a grounding issue?? All sensor grounds return to pin 20 on the MicroSquirt and not the chassis ground.

Is the laptop plugged into the wall, or running off of a battery? Laptops power supplies can be coupled to the power line (thu a small capacitor) and the same for the scope. So if you can run the laptop off of a battery that may help. Also, battery chargets hooked to the vehicle battery will cause grief, and the scope can cause a false return back.

I would check the ampseal to make sure that the VR wire braid is hooked to pin 33 and the center conductor to pin 32 - this is where the wires go into the ampseal header. In the beginning a few wire harnesses were constructed backwards, so its good to check this.

Also make sure you have crank wheel mode and 12 teeth with one missing selected in the ignition settings - or you will never get sync.

Finally, I would check the polarity of the VR sensor as it is connected to the VR+ and VR- ... you can swap easy enough to check this. I would also verify that the sensor is not shorted to ground - to do this unhook the sensor two wires from the MS and check the resistance of the VR sensor wires independently compared to ground - i.e. hook one lead of an ohmmeter to ground and check each VR wire. There should be really high resistance, like in the megohms.