Wacky Tach

[91CamaroRS]

It's quite alarming to see my tach bounce under acceleration. Taking it slowly, it'll go just as it's supposed to. Under around 50% throttle, once it hits 3500 and a few points above that, it'll bounce. Not a little bounce either. Sometimes it's just a couple hundred rpms, sometimes it bounces a couple thousand. Experience with my car being stupid with ignition wires, I assume it's an electrical problem. Anyone have this problem before or know how to fix it?

[3.4 slow to go]

replace w/mini tach, filter thing might be crapped , get stock tach rewired.

just some suggestions

edit: my old 77T/A had a tach problem too, would read 200 rpm less at idle, and at 60 700 less, and at 120 1500 less. Verified w/mini tach.

[ June 03, 2003: Message edited by: 3.4 slow to go ]</p>

[Jerriko]

Have you done anything to the tach such as install overlays?

[91CamaroRS]

<blockquote>quote:</font><hr>Originally posted by Jerriko:
Have you done anything to the tach such as install overlays?<hr></blockquote>

I don't know what overlays are... So I'm going with no.

[91CamaroRS]

<blockquote>quote:</font><hr>Originally posted by 3.4 slow to go:
replace w/mini tach, filter thing might be crapped , get stock tach rewired.

just some suggestions

edit: my old 77T/A had a tach problem too, would read 200 rpm less at idle, and at 60 700 less, and at 120 1500 less. Verified w/mini tach.

[ June 03, 2003: Message edited by: 3.4 slow to go ]<hr></blockquote>

So its an electrical problem with the tach itself? I just want to know if its something like a plug not firing or a wire not working right or the rotor missing a contact or something like that... If its just an electrical problem and its not causing the engine any harm or foul, then I guess I can live with it.

[Pewter99Camaro]

Just put in a 5" autometer

[91CamaroRS]

<blockquote>quote:</font><hr>Originally posted by Pewter99Camaro:
Just put in a 5" autometer<hr></blockquote>

Any other solution besides ignoring it? I don't like those big things.. Kinda gaudy if you ask me. And like I said, if it's not hurting the engine and its just a weird tach, then I'm fine with it.

[3.4 slow to go]

check around, do internet search. Maybe even resto places. Older cars have had tachs rebuilt.

[91CamaroRS]

Just to be definitive....

Does anyone think there;s an engine problem or is it just the tach? If there's no harm being done, I can live with it.

[3.4 slow to go]

hook up a digital volt meter w/tach option. compare with dash tach. That should answer which is at fault.

edit: when it bounces, assuming you have an auto, does it affect the drivability any? I had a TCC crap out of a 93 Bonnie, and it did the tach dance before the tranny finaly died (different story)

[ June 06, 2003: Message edited by: 3.4 slow to go ]</p>

[91CamaroRS]

<blockquote>quote:</font><hr>Originally posted by 3.4 slow to go:
edit: when it bounces, assuming you have an auto, does it affect the drivability any? I had a TCC crap out of a 93 Bonnie, and it did the tach dance before the tranny finaly died (different story)

[ June 06, 2003: Message edited by: 3.4 slow to go ]<hr></blockquote>


The tranny was just rebuilt last march/end of last february. No problems there except a harsh kick in the 1-2 shift (I say use that to my advantage for street racing and get it fixed when I move to Florida in 3 weeks by the guy who rebuilt the trans). And yes it's an auto. And to answer your question, I haven't felt any sputtering or harshness under acceleration when it happens.

[lando_pr]

Maybe this will help a bit. I'm having the same problem with my '91 GTA

http://www.fbody.com/cgi-bin/3gen/read.cgi?msgid=33850

[91CamaroRS]

Ok.. this is all good and well... But has anyone actually had this problem, found the source, and figured out how to fix it?

[Jerriko]

Have you checked the distributor cap? The tach feed plugs into it. If the connection is bad or corrosion is present, that will mess up your signal. It will also give you a lower reading than correct since the signal would be reduced.

[91CamaroRS]

<blockquote>quote:</font><hr>Originally posted by Jerriko:
Have you checked the distributor cap? The tach feed plugs into it. If the connection is bad or corrosion is present, that will mess up your signal. It will also give you a lower reading than correct since the signal would be reduced.<hr></blockquote>


I just changed the cap and rotor... Maybe somethin got knocked loose. Ill check that out. thanks.