Tachometer bouncing around
Hey guys... lately I've been seeing my teach needle bouncing around up and down but it's not affecting how the jeep is running. About 6 months ago I replaced the crank sensor because the jeep would cut out sometimes while driving but at that time when it was exhibiting those symptoms the teach never bounced around, it would just cut off and restart back up a minute or so later.
Any ideas what it could be? I have one other person driving the jeep lately and they haven't mentioned anything strange about the way it is running... is it the crank sensor that sends the signal for the tach? Maybe the new sensor is on its way out?
I appreciate any help or suggestions.
(1993 Grand Cherokee Laredo, 4.0 litre)