tach problem?

tach problem?

hi i'm new here so bare with me please. I own a 92 corolla DX with a 5spd. I decided to hook up a tachometer and it works ok except when i kinda get on the gas (in gear) and put the engine under a load the tach starts jumping. but if i just barely give it gas and slowy accleterate it stays nice and steady. I dont notice a miss in the engine but who knows maybe there is and i just cant tell. what do you guy's think the problem is? the cap and rotor and wires are all only a few months old.

what about when you free rev the engine? does the tach stay steady?

what kind of tach is it?

the old skool induction tach where you wrap a wire about the 1st sparkplug wire or the new kind where you connect it to the wires in gauge cluster?

it's the standard electronic tach that hook's up to the - side of the coil. or the -IG port in my case....same thing obviously. i'm kinda wondering if maybe i just have a plug wire that is grounding out when the engine get's under load maybe, idk

Maybe it's just the voltage program?

yes if i'm in neutral and rev the engine the tach works just fine.

well i just put on a new cap, wires, rotor, and plugs. just to make sure and it still does it. what do you mean by the voltage program?

maybe borrow another tach and attach it to see if it does the same thing. that way you can isolate if it is the actual tach unit itself or the signal being sent to it.