my 98 GSR's tachometer started to "jump" a few days ago. it would jump whenever i'd hit about 3200 and jump to about 3800. then it went away for a few days, and just yesterday it started doing the same thing again. now this morning the thing wasn't even close to being where it was supposed to be. like in 2nd gear it would jump all the way to 6000 and i know i wasnt even going that fast. my speedometer seems fine and there aren't any noticeable engine response changes, no noises or anything. so do i just need to replace the whole cluster? or is it a sensor that's malfunctioning.? can i get that new or junkyard? the car has like 120k miles on it...any help would be nice. thanks.

 

Could just be the ICM inside the distributor, could be the whole distributor. I've had both go bad.

I have a ICM for sell in my sig if you are interested.

 

Sounds like a bad coil or ICM. Use a multimeter and check resistance between primary and secondary coil.