If you’re running RaceCapture/Pro MK2 and you’re experiencing noise in the form of high RPM spikes, try the beta firmware we just made available that just might solve your problem.
Where it should help
- If you’re using CoilX tapping directly into your ignition coil, and you’re still seeing periodic spikes due to extra noisy ignition systems
- If you’re tapping into low voltage ECU tachometer signal that should be a clean square wave, but noise on that line triggers high RPM spikes
How it works
Ideally, the RPM signal should be a clean square wave between 5 and 12v. RaceCapture/Pro MK2 has built in Schmitt Trigger buffers that will clean up a signal – to a point. In severe environments, noise can exist in the signal which shows up as false triggers and subsequent RPM spikes / glitches. Typically, this noise occurs shows up as a ringing signal following the actual pulse – often seen as a component of the ignition pulse flyback.
The RPM firmware in this beta release works by triggering on the falling edge of the signal, and ignores noisy signals for a period of 4.5 ms after the primary pulse triggers. Why 4.5 ms? When measuring RPM from an engine, this is roughly the right duration to handle an RPM signal ranging from 0 to about 15K RPM.
Using the Beta firmware
Assuming you have RPM already connected, all you have to do is apply the new firmware and monitor your engine’s RPM – no need to update any additional settings, providing you were getting correct RPM readings aside from the noise. In case you need to double check, use the following screen shot to aid your configuration. Ensure your channel mode is RPM, Timer Speed is Medium and Pulse Per Revolution is set correctly (usually it’s 1,2 or 3 depending on the number of cylinders and coils)
It’s always good to back up your configuration, even though your config will be preserved if you’re running the latest 2.8.x release.