TACHOMETER all over the place...runs good

rickbert

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Hi...new to the forum.

I have a 94 Suburban 5.7 that has been the ABSOLUTE best vehicle I've ever had....188k miles in awesome condition inside and out...still looks new.

HOWEVER in the last week or so I've noticed my tach needle just bounces and hops all over the place....BUT the engine does not.

It starts ok, idles a tad rough but doesn't die and runs fine once I get it going down the street. It does have an exhaust leak right in front of the muffler that I've let go for about a year cuz I like the sound. I have not tuned it up in a couple years so that might explain the rougher than normal (but not totally bad) idle. And as you all know a tune up is easy so I will do that.

So is it POSSIBLE that the tach jumping all over the place is JUST SIMPLY the TACH itself that has worn out and that it has NOTHING to do with ANYTHING else and is not worth worrying about or fixing ? OR does it and the kinda rough idle go hand in hand meaning that it's a sign of another part maybe STARTING to go bad ??
 
The tach gets it's signal from the distributor. You may want to check the connector on the distributor cap. Depending on how many miles those couple of years covers, a tuneup including cap, rotor, and wires may be due.
 
New cap and rotor and the MIDDLE wire which was corroded to hell inside after less than 2 years and she runs like NEW again. Fires right up, idles smooth, runs great.

I NEVER knew a bad cap could cause the tach needle to act so jumpy and give false readings but that was it.

Thanks
 
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