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I know a little but not alot

My tachometer above 3000rpm's jump all over the place, and im not sure what it is, maybe someone may have had a similar problem, can anyone plz help ive been racking my brains and still nothing.

so what your saying is, if you rev your engine past 3000 its ungoddly inacurate and sways around?

Does this happen even if the car has been running/driven for more than 20 minutes?

I havnt had this problem with my tach, but on cold days, my speedo will go crazy and make lots of noise when i go over 20mph and it hasnt warmed up....

If it is because its cold, rumor has it, the problem has something to do witht the luberacation to the cord that runs the speedo... possibly the same with the tach?!?!
i have not had the time to inspect... but thats my 2 cents


good luck

Is your engine misfiring when the tach goes nuts or does it seem normal? If normal I would inspect your ground connections.. I had a tach on my old nova that had a bad ground and it would do the same thing.

Tunes67

Is it an aftermarket? if so hold the press! I know what the deal is. If your tach going nuts over 3,xxx you probably need to consider using a better ground connection. I JUST fixed this same problem with my autometer tach. I couldn't figure out why the needle would just dance around like it did. my buddy came over and he just put new connectors on the current leads and sanded off the surfaces with a enery board, then cleaned them with a little alcohol, BOOM problem fixed! also if you have a lead going through the firewall for the IG+ connection MAKE CERTAIN it is properly insulated, I used about 5' of rubber vaccum hose to cover my wires, you short that lead and it may be time for a new ignition, or a new ECU.
Hope this helps
John

Its the stock tachometer, but i have not checked the ground, nor do i know where it is, its strange, but so far i think i might be leaning towardws the ground, it only happens over 3000rpm, so i though maybe it waa an ok ground, it doesnt matter how long the car runs for it always does it, but today for about 30 seconds it was fine the first time ive ever seen it work

Its the stock tachometer, but i have not checked the ground, nor do i know where it is, its strange, but so far i think i might be leaning towardws the ground, it only happens over 3000rpm, so i though maybe it waa an ok ground, it doesnt matter how long the car runs for it always does it, but today for about 30 seconds it was fine the first time ive ever seen it work

now I was assuming that it was an aftermarket tach. being that it is the stock, it could be a dirty contact on the plastic flexible cable/pcb that they attached to the back of the instrument cluster. try getting some alcohol or some contact cleaner and wipe off those connections. if this doesnt work I would look into just getting an instrument cluster from someone and if you feel very McGuyver-ish you can just remove the tach from the one cluster and replace the one thats all fritzed out with one that works. I had to do that with my fuel gauge. I broke the needle off when I was installing my indiglos

now I was assuming that it was an aftermarket tach. being that it is the stock, it could be a dirty contact on the plastic flexible cable/pcb that they attached to the back of the instrument cluster. try getting some alcohol or some contact cleaner and wipe off those connections. if this doesnt work I would look into just getting an instrument cluster from someone and if you feel very McGuyver-ish you can just remove the tach from the one cluster and replace the one thats all fritzed out with one that works. I had to do that with my fuel gauge. I broke the needle off when I was installing my indiglos