RPM gauge started fluttering very slightly and when it happens it does it no matter if I’m giving it gas or idling, now it seems problem isn’t there in the mornings but after work when I start my truck it does it. Wondering if anyone has any ideas or have had the same problem

 

What's the problem? The needle is moving when you think it should be steady? Get a known-accurate tachometer and compare their readings.

 

would a obd2 reader tach be a known working one? Otherwise how would you hook up a known working one?

 

Replaced spark plug wires and cleaned rotor and cap and misfire rpm engine flutter is completely gone!! I think what happened was I drove my truck for about 2 hours one way to go shorting a couple months ago and the way I had my wires routed they got burned and cracked and usually I only drive 3 miles one way a day. So it finally had enough time to burn the wires and created a misfire

 

Yes, a scantool showing the RPM PID would be very accurate. But you'd hook up an external tach exactly the way its instructions say, which is probably exactly like the factory tach: 12V, ground, and the negative terminal of the coil. Unless the plug wires were resting against the exhaust manifolds, or they were VERY low-quality, they shouldn't burn for many years.

 

One of the wires was resting on the exhaust manifold and they were probably crappy wires because one was burnt and it was on the valve cover. I’m an electrician and I do insulation resistance testing at work and 40,000 volts has the potential to track across a dirty path or through bad insulation glad I got it solved though thanks for the help steve