[rusEfi] Hunchback 1991 Miata NA/NB2 rusEfi official racecar #20

[kb1gtt]

Do you have a schematic for the charging system you have?

[AndreyB]

Do you have a schematic for the charging system you have?

Top post here https://rusefi.com/forum/viewtopic.php?t=906#p16266 has some links

Just added https://rusefi.com/wiki/index.php?title=File:1991_wiring.pdf into https://rusefi.com/wiki/index.php?title=Vehicle:Mazda_Miata_1990

[kb1gtt]

Some thoughts,
-- Check the alternator connectors, including the GND for the alternator. Keep in mind the bolts that connect the alternator and the motors ground strap are critical. Polish the alternator bolts, and make sure were the alternator connects to the engine is also polished. As well make sure you have good fat ground straps with polished connections.
-- If you have inductive loads like an injector or ignition coil, those can cause voltage spikes which dump back to the battery rail. Frankenso has the Over Voltage Protection MOSFET's, so those should not be dumping back to the battery. However if something is wired wrong, those are clamping at 40V, so they could possibly be dumping back to the battery. Make sure you do not have a diode between your injectors and battery. Also you can look for similar on other inductive loads like the ignition, perhaps the fuel pump. Perhaps try disconnecting injectors and see if the voltage drops, and perhaps try similar with other inductive loads.
-- Could it perhaps be a broken alternator, can you try a new / different alternator?

[NBytevenom]

Is only the ECU showing the high voltage?

I had a similar issue with an MS3X that was receiving a totally wrong voltage somehow. It turned out to be the patch harness. NBs have different pinouts between the years. I believe 03-05 are different than 01-02. Just something to look out for.

[AndreyB]

It's ALIVE!

Here we see new owner applying new numbers! I hope they would update firmware at some point since back in the day there were random misfires

image.png (1.39 MiB) Viewed 29589 times

[AndreyB]

And now it's under new ownership _again_ and new owner is not happy with the tune New owner was expecting a perfect tune since my old car.