Tachometer question....

1986 Honda Accord LXi

The tachometer, for the most part, seems to be working fine, but I started noticing a bit of an anomaly around 4K rpm when accelerating. It seems to wobble or jump. When the RPMs are below 4K, no problem, the tachometer is solid.

I guess what I'm asking is, what should be looking for?
Is there a potential problem on the horizon?

The engine runs great. Everything is firing just as it should.
The car does have 400k miles on it, I wouldn't be surprised if it was a bad tachometer.

I don't think the tach is any more than a coil of wire that turns clockwise the more electrical pulses that go through it. The source of those pulses is the ignitor. Idk it failed on my car once and it acted similar to that, but it ran very poorly up top. They are also very likely to fail.

Yeah I agree 400k miles I would look at the ignitor first I never heard of our tachs going bad.

I have had 2 aftermarket tachs go bad one wouldnt let my 440 start unless I disconnected it.

This is a common problem. You can remove the gauge cluster and spray lube down inside the cable that runs the tach. Also first things first check the cable underneath the hood and make sure it secured properly. If it isn't then it can cause the wobble.