i have a d16z6 and i got a 5" autometer tach n installed it. everybody worked out fine then a couple days lata the afta market tach needle started jumping n i didnt kno wat was goin on. like the car will be at 3500rpms and the needle bounces from 4 n 5 until i rev pass 5. the tach reads accurately till 3000 afta it just jumps. so i unhooked it n now my stock gauge cluster tach does it also. if anybody has this problem n solved it please help. it doesnt really effect performance or the way it runs just weird y it does that. thanx ahead of time.

 

your dizzy is going bad. i think its the coil in there that is actually going bad.

 

My buddys car also did this but with the stock tach. It turned out we added the ground going from the transmission to the body under the battery bracket. We also had the lights diming down at certain rpms and the stereo wouldn't work and the cigarettte lighter accessory plug wouldn't work.

 

so is what ur tellin me is to ground the tranny wire under the battery bracket to the body. or u tellin me to add a ground. is this wat fixed ur friends problem tho. my stock tach is doin it to now. so thanx for any info

 

Jerry,
I concur with adding a ground wire/cleaning/tightening the orig. wire.
Best grounds go straight to the batt ground terminal.-Bob