Why is my car tachometer jumping?
What causes tachometer to fluctuate? A blown fuse is a potential problem with the tachometer. Bad wiring can also be the cause of a malfunctioning tachometer. If you are getting erratic readings, this can be a sign of bad wiring.
What causes the tachometer needle to bounce while driving?
The bounce of the tachometer needle happens when speed is constant under little to no torque, anywhere between 30-58 km/h, the RPM ranges 1300-1800-ish {if I press or release the accelerator slightly the RPMs stay steady, and the bouncing tach needle stays steady}.
Why does the tach needle keep moving up and down?
The tach needle bounces up and down instead of holding steady. If you hold the engine at a constant speed, the needle continues to move around. Shift lights fire at odd times, usually long before redline.
What can I do about erratic tachometer needles?
SPA tachometers seem to be particularly sensitive to these spikes, but Auto Meter and Stack tachs seem to be much less affected. The fix is to add a simple 47k Ohm resistor (1/4 watt, 5% to 10%, rated to 500v) in the RPM signal wire from the coil to the tach.
Why are the lights on my tachometer jumping around?
A needle that jumps around and shift lights that fire at random may look like a huge problem, but in fact they are usually caused by a simple issue that is easy to fix. First, let’s narrow down the symptoms. Too many times we get emails that just say the tach is “acting weird” or is “inaccurate”.
The bounce of the tachometer needle happens when speed is constant under little to no torque, anywhere between 30-58 km/h, the RPM ranges 1300-1800-ish {if I press or release the accelerator slightly the RPMs stay steady, and the bouncing tach needle stays steady}.
A needle that jumps around and shift lights that fire at random may look like a huge problem, but in fact they are usually caused by a simple issue that is easy to fix. First, let’s narrow down the symptoms. Too many times we get emails that just say the tach is “acting weird” or is “inaccurate”.
The tach needle bounces up and down instead of holding steady. If you hold the engine at a constant speed, the needle continues to move around. Shift lights fire at odd times, usually long before redline.
SPA tachometers seem to be particularly sensitive to these spikes, but Auto Meter and Stack tachs seem to be much less affected. The fix is to add a simple 47k Ohm resistor (1/4 watt, 5% to 10%, rated to 500v) in the RPM signal wire from the coil to the tach.