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No spark LT8

Old 06-09-14, 02:11 PM
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No spark LT8

1987 TII
Stock ignition and CAS
Taurus Alternator

Car had LT8 installed and wired up about 3-4 years ago and has been running ever since. Yesterday I put in a new fuel pressure regulator, but found the car had a dead battery (sat for a week, not sure why the battery died in a week as it is a fairly new battery).

So we jump the car, and fire it up with the purpose of tuning the car. Car immediately acts like it has a spark issue.

After much inspection, we find that nothing seems out of the ordinary in terms of ignition components. We go to fire it up again, but this time it won't even start. Throwing a timing light on reveals we are not getting spark out of any of the coils, and the microtech confirmed this by showing 0 RPM (as well as my tachometer).

Threw in another CAS I had kicking around, same issue. Checking the connector at the microtech shows continuity from the CAS to the ECU. Microtech was also flashing orange when cranking as well with solid green light and no red light.

So we put the microtech in test mode by changing cylinder value to 0. We try cranking and we DO get a spark signal from the microtech (my understanding is it takes the CAS out of the equation and generates it's own signal). The plugs were firing at while in test mode as well as an RPM signal on my tachometer.

We then take it out of test mode and again I have no spark signal coming from the microtech but this time, the red light flashes and returns a "no rpm" error.

I am starting to think my Microtech is dead... possibly whatever part of the ECU that receives the crank input.

One thing of note is I drove around with a 1.0V voltage drop from the alternator to the battery (for a few weeks). I discovered that the microtech was wired to the alternator which was pumping out "15.95" volts at times to compensate for the voltage drop... I fixed the voltage drop issue last week with some fresh wiring. Is it possible the microtech did not like that 16volts and burned something up?

Any thoughts. suggestions???

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Old 06-14-14, 10:16 AM
Engine, Not Motor
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I guess the only way to confirm this would be to connect a CAS directly to the Microtech (connectors are the same as those used on ATX computer power supplies) through a short harness and then spin it by hand. If it picks up RPM, the Microtech is good.
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