lakeffect2

I thought I was at the end of a motor swap, but can't get any firing.
(400block with TPI, High flow manifold, SLP runners, 236 cam headers into a 93 Caprice wagon)

Having used the search function, I've confirmed that the ignition system is capable of firing without the ECM in play. The ECM seems to control, WHEN spark occurs (advance/retard) bit not the fact that it happens.


I have an entirely new ignition system, distributor (HEI REMOTE), new module (tried a few extras when it wouldn't fires) new coil (tried a spare there too) new 8mm Accel wires, new plugs @ 40 gap. New motor harness from Painless Wiring Like I said EVERYTHNG NEW.

I have 12 volts to the HEI coil, I had two modules tested by Advance Auto against an off the shelf piece for comparison.(they all worked)

If I understand correctly,the signal starts at the reluctor, gets amplified by the module, passed to the coil (and ECM for timing adjustment) where the pulse from the module triggers the coil to fire.

Proof that the coil is not firing comes from two things, an inductance style timing light shows no light, (but worked fine on other cars) and an accidental grounding of the tach lead allowed the engine to fire a few seconds before I yanked the wire.

(scared the $h!t out of me, 450horse- no headers KABOOMALAKALAKALAKA hearing returned to normal about same time underwear was changed)

The fact that grounding the lead allowed the coil to fire seemed to verify no signal coming to the coil from previous parts of the system.

My questions of HEI remote systems are:

Is there more than one style of reluctors and ignition modules due to make model changes, and therefore a mismatched set? Maybe I have the wrong ones trying to work together?. Remember this is not an engine that belongs there, it's a swap. It used to be a 350 TBI

How do I test the output of the reluctor signal with limited tools ( no scope and just radio shack VOM) It's two wires going to the Ignition module.

As the motor turns over,what can I determine, what voltage should I see out of the Reluctor coil?

Can I test output the the coil from the module? The modules themselves were independently tested as working, but can I test the output to see a signal actually getting to the coil to create the triggering spike to release the pulse to the cap.?

I've been frustrated for the past year trying to make things happen. I welcome your thoughts, and thank you for taking the time out your your day to answer.


Dave Buchholz, Rochester NY

Supervisor42

Take a look at the attached schematic for the stock TPI ignition system.
The pickup coil is connected to the amp. The amplified (not strong enough to fire the coil) signal goes two places:
It goes out the purple/white wire to the ECM to fire the injectors and get it's timing "adjusted" when in bypass mode.
If the tan bypass wire is not energized, it goes to SW-B that opens and closes the solid-state "points".
When the tan wire is energized the switch shown at the top connects SW-B to the white wire which is the "timing adjusted" signal coming back from the ECM.
The best way to test the dizzy is to unplug the 4 wire plug and spin the engine over and check for spark. The engine won't run because the ECM is missing the signal for it to fire the injectors.
If it fires, the problem is outside of the dizzy. (such as grounded ppl/wht wire or tan wire energized and no signal coming back to the dizzy on the white wire)
If it doesn't fire and the module is good, then the pickup coil is bad.
The reluctor (timing core) is just a metal wheel that directs magnetic field up to the pickup coil. The only problem it has is when it gets loose on the shaft and slips around.

lakeffect2

Thanks for the response. It will help me understand how the system works as well.
If I want to check the output from the pickup coil to make sure a signal is getting to the amplifier, is there an appropriate way to do so?

Supervisor42

You can't really check the output of the pickup. The voltage is in milivolts. You can check the output from the amplifier (in the module) by disconnecting the 4-wire plug and checking the voltage coming out on the pin that connects to the ppl/wht wire with an analog meter (cheap one with a needle).
If the pickup is triggering the module, the needle will bounce when the engine cranks.
Some other checks you can make:
Ohm the picup coil: should not read open, about 300-500 ohms
It should read no continuity to ground.
Verify that you have adequate voltage on the coil when cranking. Should be at least 10 volts.
Verify the ppl/wht wire is not shorted to ground.
Verify the tan wire doesn't have voltage on it when cranking.