Car is a 2000 Corolla CE.
When going at the desired speed (say 40mph) and there is lots of coasting room, I just let go off the accelerator and the car basically coasts. The engine RPM drops from 1600-1800 down to 900-1000 and it actually can coast a long way. Sometimes, I need to go faster (if I’m initially started at a slower speed) and when I press the gas pedal slightly, the tachometer shows the engine rpm jumps from the coasting 900-1000 to 1600-1800.
Is the tachometer (add on by ScanGuage) reporting it correctly? Is this a bad form of acceleration for the engine?