Twitchy tach?
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Twitchy tach? Starting last week I noticed that my tach is twitching a bit. While at steady part throttle, it'll intermittently spike upwards a couple hundred RPM then immediately drop back down to where it's supposed to be. I've also seen it do this sitting at a stop light. Doesn't take more than a second or two for it to drop back to normal.
Any ideas?
Any ideas?
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Re: Twitchy tach? The engine is idling at the correct RPM. The needle only takes maybe a second total to rise and fall ~500RPM regardless of which RPM I'm at when it occurs.
Re: Twitchy tach?
Starting last week I noticed that my tach is twitching a bit. While at steady part throttle, it'll intermittently spike upwards a couple hundred RPM then immediately drop back down to where it's supposed to be. I've also seen it do this sitting at a stop light. Doesn't take more than a second or two for it to drop back to normal.
Any ideas?
Any ideas?
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TECH Enthusiast
Joined: Oct 2002
Posts: 595
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From: Chicago
Re: Twitchy tach? my tach does this sometimes too. at first I thought it was because my battery was taking a dump and the car was trying to rev itself to compensate for the low charge, like what it does when you jump it sometimes. I've sinced upgraded to an optima red top after the stocker finally basically exploded (haha that's another story all together...) and the problem is still there. i'm thinking I have a bad plug or plug wire because i sometimes get a few backfires on cold starts and on shifts until the engine heats up. whenever I have the time to do my next mod (nitrous or headers I can't decide 
) i'll toss in some new plugs and see how it goes.
) i'll toss in some new plugs and see how it goes. LS1 Tech Stories
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Verdad Gallardo Re: Twitchy tach? Is the tach moving independently of the engine speed or are you getting surging? I want to be certain what kind of problem were looking at here: engine surge or tach/speedo malfunction.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Re: Twitchy tach? Hey Chris! Yes, it has been a long time!
The tach moves independently of the engine speed. I do get normal surging at low RPM's, but that surging barely impacts the speedo. The last time I noticed it, the speedo went from 0 to about 10MPH, and the tach jumped about 500RPM in the same timeframe (about a second?)
The tach moves independently of the engine speed. I do get normal surging at low RPM's, but that surging barely impacts the speedo. The last time I noticed it, the speedo went from 0 to about 10MPH, and the tach jumped about 500RPM in the same timeframe (about a second?)
Re: Twitchy tach? Any ideas?
[/quote]
I have the same problem, except its with my speedo. Its been doing it for the past couple of months and I can not find a solution to it!
[/quote]
Look closely at the battery cables... AC Delco batteries especialy often leak from the positive post and corrode the cable. this corrosion can cause the spikes on your tack and speedo. i had the same problem when i had my 98' camaro. i replaced the leaking battery, and was able to clean the terminal enough to reuse it. you may have to replace it. after i did all that, the problem went away... took like 6 months before i tracked it down! hope this helps.
Re: Twitchy tach? I have the same problem, except its with my speedo. Its been doing it for the past couple of months and I can not find a solution to it!
[/quote]
Ditto that. Something sounds as if it's causing a spike in the system.
Sent you a pm Jim.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Re: Twitchy tach? I have a Optima Redtop, but there was some white powder between the battery cable and the battery terminal. I used a wirebrush to scrape as much of it off as possible...so far so good! I don't recall which terminal it was, but the other cable had no white dust on it whatsoever.
However, I did notice a very small bit of seepage around the top seal of the battery. When I would pull on the battery to check the mount, I'd get a small bit of brownish-orange residue on my fingertips. Didn't recognize the taste. J/K.
That reminds me, I need to replace a PCV tube on the rear driver side head. It's torn.
However, I did notice a very small bit of seepage around the top seal of the battery. When I would pull on the battery to check the mount, I'd get a small bit of brownish-orange residue on my fingertips. Didn't recognize the taste. J/K.
That reminds me, I need to replace a PCV tube on the rear driver side head. It's torn.
