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| biggrizzly | Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
 
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Since my engine replacement I have noticed my tachometer bouncing around over rpms of 2000 or so. The higher I rev, the more wildly it bounces? WTF?
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Posted on: 2011/8/7 2:36
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| bogus | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Grand Imperial Pooh-Bah
 
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tach filter has an issue.
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Posted on: 2011/8/7 3:45
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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Do the 92 and up have a tach filter? I'll have to look that one up. Didn't know we had one
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Posted on: 2011/8/7 23:49
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| tjpreul | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
 
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There is one for the 92-93, but I don't know on 94-96. |
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Posted on: 2011/8/8 4:28
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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I think I found it on the passenger side under the fuel rail in the same wire harness as the opti stuff. I'll check the wiring to make sure everything is tight and has good connections. Thanks
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Posted on: 2011/8/8 12:03
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| tjpreul | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
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Check the output voltage on your alternator. A month after I bought my car the tach started jumping, so I bought a filter. Before I installed it I noticed the alternator was charging at 16v. I put on a new alternator and the tach stopped bouncing. I still have the filter in its package, but it is 92-93 only.
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Posted on: 2011/8/8 12:18
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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I just put a brand new alternator in the car when I installed the motor. I suspected the alternator for a fluctuating voltage so I replaced it. Then I found out I had a loose ground at the starter. I could throw the old alternator on there to check it out. The new one seems to be steady on the voltage in my scans but I need to go back and look at it again.
Thanks for the ideas |
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Posted on: 2011/8/8 13:55
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| 1Fast04Vert | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
 
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I checked my 95 FSM and there is no mention of a tach filter. Best I can find out it gets it's input from the PCM. I am guessing the change happened when the ECM became a PCM in 1994.
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Posted on: 2011/8/8 15:47
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2004 Vert. 475hp. Built by Vengeance Racing |
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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I found it in my 1994 FSM. It is there. Mine is located on the passenger side in front of the fuel rails and off the engine harness.
See image. Item no. 7 is the tach filter connector. The other image is a photo from my car. I pulled it up into view so I could photograph it. Was hanging in the wind under the that coolant hose. Also - Ecklers has the same part no. but only lists its use up to 1993 GM. Part #12088559 is for 1991-94 is discontinued. 1994 is the last year that used a tach filter. http://www.ecklerscorvette.com/corvet ... ng-harness-1992-1993.html Attach file:  TachFilterEngineWiring.jpg (803.79 KB) Tach-Filter.jpg (284.67 KB) |
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Posted on: 2011/8/8 16:12
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| 1Fast04Vert | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
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You made me go out and look at my FSM again. No tach filter in the diagrams either on mine. Guess it changed in 95.
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Posted on: 2011/8/8 16:25
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2004 Vert. 475hp. Built by Vengeance Racing |
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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Yup... I just did a Google search and 94 was the last year for a tach filter. I wonder what they do on the later year cars? |
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Posted on: 2011/8/8 16:28
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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Quote:
94 uses the same part no. as 93. I'm just curious if that is the actual problem or not. Would you be interested in finding a new home for it?  |
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Posted on: 2011/8/8 16:33
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| tjpreul | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
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I can get it shipped/mailed tommorrow. |
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Posted on: 2011/8/8 17:44
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| biggrizzly | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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2011 Memorial Day Car Show Winner!
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Tyler - you will probably shoot me!!! Especially after packing up and shipping your tach filter.
Apparently just by moving the tack filter away from making contact with the coolant hose and other hot engine parts it has started working properly. I have not seen the needle bounce once since I went in there and moved the harness around and moved the tach filter away from the coolant hose. Oh well.. I'll hold on to it for a while and see what happens but if you want it back at any time let me know. |
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Posted on: 2011/8/10 12:52
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| joeld | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Guru
 
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I was looking at the picture from the link to Eckler's and noticed the "eyelet" that appears to be a ground source. I on my 89 if the filter does not have a real good ground the tach will be "lazy" and bounce some.
Joel |
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Posted on: 2011/8/10 18:03
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1989 Coupe,L98 automatic |
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| tjpreul | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Elite Guru
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Maybe its magical. After I bought it my tach stopped bouncing too. I don't mind if you keep it, send it back or pass it on. |
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Posted on: 2011/8/11 2:28
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| bogus | Re: Bouncing Tachometer Needle above 2500 RPM | ||
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Grand Imperial Pooh-Bah
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I have one from my 1992, too. If anyone needs it... just be patient, it's in a box somewhere.
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Posted on: 2011/8/11 17:41
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_________________
The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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Transfer
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