My tach has been acting up for a year now and I think its time to get it squared away. On the pink tach wire there i a grey quick disconnect clip, is this the tach filter? Do I have a tach filter? If this is can I remove it? My tach is basically reading 2-3 grand higher than the engine is revving and any time i give it gas it gets pinned. Can the tach itself get fried? Any help would be great.

 

Tachs can get fried (voltage spike or plain old age). It could be something as simple as a bad connection too.

A sidenote,, the tach wire is the small white wire on the coil. The thicker pink wire is the power for the coil (from the ign switch).

 

Yeah sorry about that I got mixed up. I was talking about the white wire and thats the one with the clip. I'm not sure why I said pink....oh well

So is this clip the filter? Or should I just get a new tach?

 

We all have our brainfart moments

From what I understand, the tach filter it a little black tube looking thing inline on the wire (something that has to be spliced out, can't be unplugged). Neither my 84 camaro (no tach originally) nor my 87 bird have one (both cars factory gauged) so I'd assume yours wouldn't either but, don't take my word on that. I forget it's purpose but, I've seen that people have to bypass the filter when they install MSD 6 boxes so the tach doesn't act all funky. If you have a tach filter, I don't see the harm in bypassing it.

If you've got the time to kill you could pull your cluster (since you might have to anyways) and wire the tach direct to the the lead on the coil to see if that somlves the problem.

 

After extensively looking at the wiring setup for my '87 IROC, I have decided that the clip is the tach filter, otherwise there'd be absolutely no reason to even use a clip.

 

Well.....it sure as hell doesn't disconnect the computer advance . We'll have to remember to take that damn thing out next time. And if it still doesn't cure the tach, it'll have to be out for the MSD anyway.

 

Or you can replace that 85 MPH speedo with something more serious and then we won't have this little tach problem perhaps .

 

both my 90 rs and my 88 iroc does the same thing cant find the problem tried hooking up the msd,6al strate to the clip still same problem, and had the problem before the msd box changed the tack with one from the parts yard same problem even changed the the little computer chip in the cluster same problem gm says u cant bye the tack or the chip they said i would have to send the whole cluster out to be fixed that sucks. i just run a monster tack off my msd box but i would like to get my fac, one working let me know if u get it fixed i will try to bypass the clip just fore the hell of it if it works i,ll let u now
later rob

 

Wow, this looks like more of a problem than anticipated. Thanks for the info. Let us know what happens and we'll let you know if we make any progress either