GMCFEATERS

I am using a V3 board with a MS1 chip. I am also using 25v2 software MSMS extra software, using megatune version 2.25B662. I am having a lot of problems getting spark. I am gettin a good signal off my VR sensor. I am using hte 12+1 method by cutting two teeth out. I have the 4.7K pull up resistors in place. All gages are reading good except for RPM. RPM gage shows yellow in megatune, and always reads 2 RPM. When ever cranking the motor over, my spark output goes from 0 to .8 volts, all 3 LEDs are constantly on at all times that power is applied. My fuel pump and primary fuel injectors do kick on momentarily as soon as power is applied. I tried to spin the crank sensor by hand but I get the same results as posted above. I went through all my programming tables and didnt see anything wrong, but is there a value or setting that I may want to look at.

I have my spart output lines coming off the pull up resister and the leg of the LED, is this correct???

Everything works on my setup except for the spark. My ignitors are known to be good at this time.

I tried reloading the embedded code, and this didnt help. Also I tried jumping D8, and again this made no difference.

Thanks everyone for there time in advance, any ideas are appreciated at this time.

muythaibxr

you won't get spark if the signals from the CAS aren't getting conditioned properly (which is why you're not getting any rpms when you spin the CAS).

you didn't mention how you set up the hardware to condition the CAS signal. Are you using the built-in vr sensor conditioner? Did you build an extra lm1815 circuit? If not, did you cut 2 teeth out of the CAS?

GMCFEATERS

I cut 2 teeth of the CAS.

GMCFEATERS

I cut 2 teeth of the CAS, and Im using the built in VR sensor, and I have the positive off the crank angle sensor going to pin 25, and I have the negative going to pin 6 of the megasqiurt. Is this the correct set up and do I have to add an inline resistor from the CAS into the line for the megasquirt. When ever I was working on the crank angle sensor jiggling the wires the car will actually start on its own and run for approx five seconds before it dies. While the car starts on its own all my LED's on the MEgasquirt for the ignition output flash as they should. I am wondering if I need to add an inline resistor. With out jiggling the wires alittle the car will not register RPM and my LED's do not funtioning correctly, almost as if only a loose connection. Again any help is appreciated.

muythaibxr

You actually want to be using pin 24 not pin 25... Maybe you typed wrong?

If you're jiggling wires and it suddenly works, then most likely you just need to check your wiring.

I've never needed any kind of inline resistor. You do need to make sure the MS is grounded at a good location though, otherwise you'll get all kinds of weird things happening with the VR sensor conditioners.

Also, make sure that both of the Potentiometers on the v3 board are set to their fully counter-clockwise positions. Later if you get noise you can adjust the top one to compensate.

GMCFEATERS

Thanks for all the help and info, I am at work right now but will check all my wiring tonight and see what I got.

custom13B

Muy just helped me resolve the same exact issue. Check that you have the jumpers soldered onto the bottom side of the MS board correctly. Check the thread on MS V3 no spark still for that. Also you need to have MSNS enabeled under the Spark heading. Go to megatune main screen and click on spark. Youll see a list of ignition options. Make sure the distributor is set to MSNS. At least on my version it needed to be set to that. Double check those pins on the db 37 I had mine wrong in the beginning...easy to miscount with all those wires in the way. Also make sure its shielded wire and only ground one side or you may create a ground loop. Just my 2 cents worth from what I learned from muy. Also I would concentrate on leading first just to make things simpler. Even get a test light out and check for power at the coil pack and proceed logically. Good luck let us know when you get it working.

Eagle7

I was just getting ready to post a similar set of symptoms. I've done what I think is a full build and full configuration to run fuel and spark on a stock harness. I've not yet connected a CAS - but with just the Stim connected, all 3 LEDs are on all the time. Is that normal?

muythaibxr

the middle LED should flash noticably at lower rpms... IF it's not, you should check your software settings with the settings I have in the FAQ.

Eagle7

No RPMs - gauge reads 2.

Eagle7

I got it working the way I assume it should by setting "Spark Output Inverted" to "Yes" (contrary to FAQ). Is this correct? This is a V3 board if that makes a difference.

Also, should "Distributor (MSnS)" be set to "Off" (per FAQ) or to "MSnS^"?

Thanks,

muythaibxr

Spark output should *NOT* be inverted.

Distributor should also be set to "off"

If you're not getting rpms using the settings that I posted.... then something about your hardware setup and software setup don't match, or you have some other type of hardware problem...

Set both of the Potentiometers all the way counter clockwise...

If you cut 2 teeth out of the CAS make sure you have it set to 12 teeth with missing tooth; if its a stock CAS with 2 VR sensor conditioners, you want 12 teeth with second trigger.

If you got rpms when you set it to Distributor, it's because the MS is only reading the Ne wheel, and it's seeing a lot of teeth. Do NOT try this in your car. It could potentially screw something up.

The guage reading 2 is normal when it's not getting a signal from the CAS. I believe it's a bug in the high-res rpm gauge in megatune, not the megasquirt itself.

Eagle7

I hope I haven't caused any confusion by hijacking this thread. I'm not the original poster. I don't (yet) have any issues with CAS or RPM, since I haven't yet even connected the CAS. My symptom is that all three LEDs are on bright all the time with no RPM. When I do a fresh progam download (and thus get default settings), the LEDs behave like you'd expect from their default funtions. As soon as I load the RX-7 settings into MegaTune and download them all three LEDs light up. I've quadruple-checked the settings and can't find a discrepancy.

Thanks,

muythaibxr

That's fine... if there's no tach signal, the lights should all glow solid; they're doing what they're supposed to do. If you haven't connected a CAS, then you shouldn't be able to get a tach signal.

This is because the lights now control ignition. When an LED is on, there is no signal going to the ignitor...

Even when you get an engine running, you *might* see the LED closest to the serial port flash a little when cranking, and then when the engine is actually started, the middle led will flash, and the two outer led's will appear to glow solid (even though they're just flickering really fast).

GMCFEATERS

Also make sure its shielded wire and only ground one side or you may create a ground loop. Just my 2 cents worth from what I learned from muy.

Am i supposed to ground the sheilded the wire to chassis ground, and if so is the am i supposed to tie the NE- into that ground.

I have the NE+ tying to the wire inside the shielding, and I have the NE- going to the shielding, is this wrong, if so can you set me straight.

muythaibxr

this is wrong...

you want Ne + going to pin 24 on the db37, Ne - should go to any of the ground pins on the db37, and the shield should go to any other one of the ground pins on the db37.

the shield should ONLY be grounded on one end (the end where it connects to one of the ms's ground pins).

Eagle7

Great. That's just what I needed to know. Thanks a bunch.

GMCFEATERS

muy,
Thanks for all you help with my problems. I think im straightened out as of now, and I saw on your FAQ for stabbing the CAS that I was using the wrong tooth (#1 instead of #3) I will try this tonight and see what it gets me. Again thanks for everything.

George