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View Full Version : Problem with tach signal MSnS using Led17


Ceides
04-06-2007, 02:56 PM
I recently took on setting up spark. I wanted to keep the fidle output free so I decided on using led 17 as my output. I came across MSnS-E ignition setup via LED17 & PWM idle control (http://forums.turbobricks.com/showthread.php?t=71300&highlight=led+17)
that had exactly what I was looking for, so I started on the modifications. I already had the harness for the ignition module in my car so the only modification that I had to make was to cut the wire to the #6 terminal on my module and solder 2 wires that both were sent to the megasquirt computer. I connected the #6 terminal to pin 25 on the DB37 connector and the middle wire from the hall sensor to pin 24.

This is the diagram drawn up by Malloy1
http://i144.photobucket.com/albums/r168/malloy1/spark_and_idle14-1.jpg


My problem is that megasquirt does not seem to register any rpm while cranking. Upon switching on the car I get one spark when led 17 is turned on.

Here is the input circuit in use on pin 24
http://megasquirt.sourceforge.net/extra/pix/input-neg12.jpg

After using a multimeter on pin 24 just before it enters the megasquirt computer I do get a signal from the hall sensor, although it does seem weak, went from 0v - ~1v. I have yet to measure it further along the circuit though.

I have tried 2 different distributors without any luck. So i'm starting to think that this pull up diagram might be on the fritz and not pulling the voltage up enough. On D8 where is says 1.3 - 2k ohm I believe I used 1.5k ohm.

Any ideas are very welcome, as if I don't get this working in the next few day's I'm swapping to the tried and tested method of using the Fidle for spark output and pulling up of pin 28.

Ceides
04-07-2007, 12:12 PM
After many hours of troubleshooting this issue the only logical explanation was that I had made some error with the pull up diagram and after going over it closely this morning I found my error. Drum roll please: So instead of using D9 as my pull up source I used R9 by mistake... I kind of feel like a slap in the face is in order

well spark is up and now it's just a matter of fine tuning :cool:

~Arnar

The Aspirator
04-07-2007, 01:32 PM
Hahaha, well done in figuring that out Arnar! Best of luck with the t00ning!

John