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Any questions you have before you begin buying, building and installing.
By Izzy46
I have an 8 pin HEI connected to a distributor on the bench. I’m using the information in the manual located here as my guide but can’t seem to get the speeduino to light up when I spin the distributor with a drill.

https://speeduino.com/wiki/index.php/Ha ... onnections

Unfortunately I don’t have an oscilloscope. After spending the morning trying to get Ardustim to connect to the UNO I’ve given up on that for now.

When I connect a multimeter to the R and G I get 1.88v while spinning the distributor with a drill. I imagine this should be reading 5v…?

+Is connected to battery positive
C is connected to battery ground
R is connected to pin 25 (crank / VR1+)
G is connected to pin 9 (sensor ground)

Pin E and B are not connected (I plan to connect these once I have a signal).

I’ve set JP2 to Hall and JP4 connected (ie, 5 volt pull up).

I’m wondering, are my connections correct, have I missed something, could the ignition module be faulty…?
By Izzy46
Hi jonbill, I had look through every post that matched the HEI search term but couldn't find the answer to my question.

Given that the model is supposed to emit a 5v signal the multimeter should read close to 5v between G and R when the distributor is spun?

I'm wondering if the 1.88v reading I get is enough to say there is something wrong with the module or have I missed something obvious.?
User avatar
The 1.88V you are reading is an average of the output, as meters are typically a bit slow to respond. If it's on half the time, and off half the time, the average would be 2.5V. If you turn slowly (and it works at slow enough speeds) you will see a "switching" of 5V to 0V and back. Some meters have a peak-hold function to read the highest voltage, but an average is fine. The module duty cycle is not 50%, so the results are not 2.5V.

I would test the module output to verify function, powered but not connected to Speeduino, as in your first post. Is the output when spinning well above 0V average? If so, the JP4 pullup is not required, and could override the function (mask the signal) if used. If the output from R is zero when spinning, the JP4 pullup is required to get the square wave, or the module is failed. Let us know what you find.
By Izzy46
This morning I did some further experimentation with TunerStudio and JP4 removed. It seems that Speeduino only 'catches' the signal after 5 or 6 spins of the distributor, once it has caught the signal it seems to maintain the signal until I stop spinning the distributor.

Using a cordless drill I jab the trigger until Speeduino 'catches' the signal, once it has the signal I can increase the RPM from 500 up to 1600 (max drill speed). The pulse width stays around 27 msec and the duty cycle moves from 0 to 70% depending on the RPM.

If I start at 0 RPM and hit the drill trigger, going directly from 0 to 1500 RPM, Speeduino refuses to 'catch' the signal (TunerStudio stays at 0 RPM).

I'm assuming that this is not the expected outcome and something is not functioning correctly here....?
By Izzy46
I went ahead and grounded the B terminal to pin 10 (ground) on the Speeduino with the same outcome. I've included a video for reference.


I'm wondering, if the module is damaged, is best to get a new one or take the signal directly from the distributor using a VR conditioner...?

Any other thoughts or ideas would be greatly appreciated.
User avatar
You certainly can run the VR signal directly to a signal conditioner on your PCB, and return the IGN trigger signal to the HEI module VR pins to use it only as an ignition coil driver. If it's damaged that may not work, in which case a separate coil driver will be needed, either as a separate driver module or in a coil as a "smart" coil. The videos floating around here of DSC prototype testing with a slow distributor speed is an example of direct VR signaling, bypassing the HEI module.

You can test the HEI module as a coil driver, set-up as you have it now, and reading the C- coil output for grounding or literally firing a coil with it. Verify your module ground through the mounting holes is solid, and good ground connection to the distributor body, as it will carry all the current and enable module function. Some auto parts stores can test HEI modules (I have a NAPA near me that can), if that helps to sort things and keep moving.
By Izzy46
Unfortunately out here in Doha where cars go to landfill after their 10th birthday there are no shops that have ever seen a HEI module let alone test one. Uncle Jeff at Amazon is the only guy I can turn to when I need a part.

I did some experiments with the C-coil pin output. I'm using a 12v battery as a power supply, it currently reads
11.5v. As a side note the output across pins P and N reads 23 mV when the distributor is spinning and the module is connected.

- grounding the B pin and the distributor spinning the C-coil pin shows 9.9v
- nothing on the B pin and the distributor spinning the C-coil pin shows 9.9v
- 5v on the B pin and the distributor spinning the C-coil pin shows 0v

The behaviour of Speeduino is the same as before regardless of the voltage at the B pin. The ignition lights will remain off unless I slowly spin up the distributor repeatedly until it 'captures' the signal.

It's interesting to note that when the B pin has 5v the C-coil pin will show 0v. When Speeduino is able to 'capture' the ignition signal (see video in previous post) the C-coil pin will show a signal of 2.5v. It seems that under the right conditions the setup kind of works however the 2.5v output would probably not be enough to fire the coil. The issue of 'capturing' the signal from the ignition module is a problem that still remains.

At the moment I think it's best if I contact uncle Jeff and get a new module......?
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