I have an RPM meter for my 40 year old truck with a points ignition system. It has both a rpm and dwell function. My Corolla has an electronic ignition system and doesn’t use points and so I don’t think that meter will work on the Corolla. The Corolla has a tach signal point I can access at the diagnostic connector. And I can access the plug wires of course.
You might wonder how I’ve measured the RPM up to now? I mean the car is over 20 years old. Well, either I’ve let them set the RPM for me when I do an emissions test, or I’ve used a lab o-scope and wrapped a few turns of wire around the number one spark plug wire. But that is sort of awkward.
I’d prefer a small hand-held battery operated rpm meter. It seems like an rpm meter wouldn’t even be as complicated as a DVM, and Harbor Freight hands out DVM’s for free sometimes. Being a frugal sort, free sounds good, but something less than $50 would be ok. So what do you folks recommend for an RPM meter suited for electronic ignition systems that is only used once or twice a year, like for a frugal DIY’er?