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Won't run with tach

Posted: Fri Dec 31, 2004 8:01 pm
by russellmopar
Hi,
I have connected the megasquirt on our Jeep (left the carb on to test the inputs) and it would not start. I disconnected the tach input from the negative side of the coil and it starts right up! While the engine was running I put it back on for a second, the engine tried to stall. It seems like the squirt providing a better ground than the points. Any help would be appreciated.


Jeep 304 amc v8 points ignition
jumper over the diode in D8
Tach works on the stim
Harness tested ok

Posted: Sat Jan 01, 2005 11:36 am
by russellmopar
I cut the jumper over d8, didn't fix it.
Also tried it on a car with Hei, same thing.

Posted: Sat Jan 01, 2005 11:54 am
by Bernard Fife
russellmopar,

You might try running a ¼ watt resistor in the wire from MegaSquirt to the tach/coil. You'll have tp experiment. Try 2K Ohm or so to start with, and up to 100K if needed. You can go as high as you can without 'extinguishing' the signal to MegaSquirt.

Lance.

Posted: Sat Jan 01, 2005 1:21 pm
by russellmopar
Thanks Lance, 47k ohm fixed it.

Posted: Sat Jan 01, 2005 1:28 pm
by Bernard Fife
Great! Let us know how the tuning goes.

Lance.