Boucing Tach - Honda Prelude Forum

jsmooney · 12-31-2001, 11:38 PM

OK, tonight I was heading up to Gasden from Birmingham going about 90 mph. I made it up there in about 45 mins (about 70 mi). but when I was coming back I noticed that my Tach was jumping while I had the cruise on going about 86 mph. I stopped at a gas station to get a MDew. Then when i was accelerating to get back onto the interstate (I-59 South) the thing was boucing all over the place, but from what I could tell, the engine wasn't doing **** as far as boucing rpms. I set the cruise once again and took her up to about 110 and it stopped boucing. It only bounces in the lower RPMs. Any thoughts on why this is happening? btw, I have a 93 Si (Silver)

Machine Head · 01-01-2002, 12:08 AM

Bouncing tac is a tell tale sign of a slipping timing belt. whats your milage?

jsmooney · 01-01-2002, 12:59 AM

I have about 97000 miles

shadowZZ · 01-01-2002, 05:53 AM

Ya its either your timing belt or your clutch is goin

Absolut · 01-01-2002, 10:39 AM

Did the pitch of the engine sound change? Does the car surge?

You migh have a problem with the tach circuit. Does it bounce all over, up and down, or does it seem like the tach is cutting out?

jsmooney · 01-01-2002, 12:19 PM

No changes in the engine are audible. I just went out and drove for about 25 mins and the tach jumps in the range of 2k-4k rpm. It does it mainly when accelertaing, but going about 55-70 mph it still jumps

Machine Head · 01-01-2002, 01:22 PM

Quote:

Originally posted by jsmooney
No changes in the engine are audible. I just went out and drove for about 25 mins and the tach jumps in the range of 2k-4k rpm. It does it mainly when accelertaing, but going about 55-70 mph it still jumps

when did you last change your timing belt? sounds like it's stretched out and slipping

Absolut · 01-01-2002, 01:31 PM

Quote:

Originally posted by Machine Head

when did you last change your timing belt? sounds like it's stretched out and slipping

If the timing belt was slipping, he would have other problems, like the valves hitting the pistons...
If it was slipping, he would be losing power and the car would surge...
This happened to my 84 lude once, the circuit that drives the tach was jacked up, it ended up fixing itself after about a month so I never really found out what was wrong. Probabally a loose connection somewhere that has problems at certain rpm's due to specific vibration harmonics, ie: it only get loose at certain rpm's.

Get an aftermarket tach and compare the two. If the performance of the car isnt affected, I bet its just the tach screwing up.

The Acclude · 01-06-2002, 07:57 PM

I had the same problem with backfiring/detonation? above 1/ throttle...I changed: EFI main relay, Spark plug wires, Plugs back to NGK laser plats, Ignitor Chip...turns out it was a damn 5 dollar rotor in the dist. cap. Try the basic ignition tune up first though.