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Tachometer Not Working Right


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#1
RYANDCOKE

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Hi everybody, this is my first post, so please bear with me. Just trying to fix the factory tach in my '85 LX Sedan. When the car is running, the tach is jumping all over the place (usually burying itself past 9,000 RPM!!), but everything else is running fine (the rest of the cluster still reads accurate). Where does the tach receive it's signal? Is it possible that this is a simple problem, because I really don't want to replace the entire cluster (my car is all original with only 169,000 kms!!) Help!

#2
Greg Gauper

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Make sure your plug wires are in good shape.

When I had a plug wire work loose, my tach did all sorts of crazy things due to electrical noise.
2011 SCCA H-Production National Champion

#3
CRXdan

I had the same problem. Replaced teh distrbitor and it fixed teh problem.
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#4
xthreetwosevenx

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a weak alternator can do the same thing. my girlfriends gti did that.
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SportInjectedClub

#5
C8V6C

My civic did the same right before the alternator gave out. Replaced the alternator and it seems to be almost as accurate as the autometer.

844b096b-9fda-4214-b621-217bc4a6dce1.jpg


#6
rally25rs

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I have simmilar issuesd, except mine only does it when its cold out... and the ammount the tech jumps up seems relative to the throttle position... the needle jumps around a bit above actual RPM at idle, and them i hit the gas it jumps over 9k hahaha! I planned on replacing the cluster cause I have 2 spares, but who knows...

#7
rpr

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That is usually a sign that the ignitor (ignition control module/ICM) is going bad. When it dies, you will have an undriveable car, as you get no spark. Either replace the distributor or just the ignitor module and the problem should go away.
"Toby, you are a thief of joy"

#8
RYANDCOKE

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Well, it has been sort of cold here of late... Every now and then it seems to be working just fine, but who knows? I will have to look into that ignition module/distributor issue. The parts all look to be in good condition, from a visual standpoint. Any way to check these parts with a somewhat limited mechanical background such as mine? I might have a voltmeter somewhere...

#9
ADDvanced

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I just replaced an ignitor module because of this thread and still no tach whatsoever.


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