12-27-2015, 09:45 AM
Hi! '94 Tracker, 1.6 TBI:
I've been playing with a programmable ignition module from JayCar. I run out of this into a CDI module from the old days ('74 maybe). When I first put this in, it ran fine, but I noticed the tachometer would stutter when I let off the throttle (coasting). When I stop, it would be smooth. It's gotten to the point the tach stutters while driving, and the engine's cutting out!
My question, where does the tach get its' signal?
The distributor module is putting out a 5V P-P square wave. That normal?
This programmable ignition has this signal and a vacuum line. You can program the advance/retard on a 15X15 matrix of Vacuum and RPM. The output of this goes straight to the CDI, and the CDI to the coil primary. It's a 300V pulse from the CDI.
Yesterday the tach and vehicle ran fine. Today it quit on the street and would only crank. I think the CDI quit, but would that drop the tach? Is there something sensing the coil output, like an aftermarket tach would attach to the switching leg of the coil primary? I have the output of the igniter disconnected from the coil. I know if the ECU or whatever doesn't see the distributor signal somehow, the injector will not work.
I disconnect the CDI and connect the igniter to the coil -, and the + to the coil +, like stock, and it works. I don't bother disconnecting the JayCar module from the dizzy.
Note: When this setup is working, gas mileage goes up, pinging is gone, and response is better.
Another note: When the igniter 'fires' the spark, it's the release (positive going edge) on the coils' negative that makes the spark. This CDI puts out a negative 300 volt pulse. Could that be the problem? Where is the noise suppressor connected?
Thanks!
Harry
I've been playing with a programmable ignition module from JayCar. I run out of this into a CDI module from the old days ('74 maybe). When I first put this in, it ran fine, but I noticed the tachometer would stutter when I let off the throttle (coasting). When I stop, it would be smooth. It's gotten to the point the tach stutters while driving, and the engine's cutting out!
My question, where does the tach get its' signal?
The distributor module is putting out a 5V P-P square wave. That normal?
This programmable ignition has this signal and a vacuum line. You can program the advance/retard on a 15X15 matrix of Vacuum and RPM. The output of this goes straight to the CDI, and the CDI to the coil primary. It's a 300V pulse from the CDI.
Yesterday the tach and vehicle ran fine. Today it quit on the street and would only crank. I think the CDI quit, but would that drop the tach? Is there something sensing the coil output, like an aftermarket tach would attach to the switching leg of the coil primary? I have the output of the igniter disconnected from the coil. I know if the ECU or whatever doesn't see the distributor signal somehow, the injector will not work.
I disconnect the CDI and connect the igniter to the coil -, and the + to the coil +, like stock, and it works. I don't bother disconnecting the JayCar module from the dizzy.
Note: When this setup is working, gas mileage goes up, pinging is gone, and response is better.
Another note: When the igniter 'fires' the spark, it's the release (positive going edge) on the coils' negative that makes the spark. This CDI puts out a negative 300 volt pulse. Could that be the problem? Where is the noise suppressor connected?
Thanks!
Harry