1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Crazy Tach?!?!?

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Old Sep 28, 2004 | 08:27 PM
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Crazy Tach?!?!?

Sorry i didnt mean to steal taht guys thread...ok so ill post what i asked here once again....

Why the **** is my TACH going crazy...its all jumpy now...and this didint happen right away after i installed the fuel pump either (which i installed earlier this morning)...i drove it around town for a while...then went to my friends place...after i left my freinds place it started to do this....the Tach is all jumpy...and its hesitating a little...what could it be now....i have alll new fuel pump and filter...all new dizzy stuff.........hmmm....any ideas guys? i have an 82' GS


P.S: thanks to those who posted their advice about this in the other thread......anyone else want to put in thier 2 cents?
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Old Sep 28, 2004 | 08:32 PM
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the car is hesitating or the tach?
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Old Sep 28, 2004 | 08:34 PM
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car is hesitating a little...tach is a little jumpy
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Old Sep 28, 2004 | 08:40 PM
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what fuel pressure are you running? mechanical or vacuum secondaries?
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Old Sep 28, 2004 | 08:43 PM
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vacuum
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Old Sep 28, 2004 | 09:01 PM
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might have some kind of interference with the tach signal, and for hesistation i would check fuel pressure
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Old Sep 28, 2004 | 09:02 PM
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Are you talking about the RPM's(tach?) or the tachometer? (still a little new to some words)

If you're talking about the tachometer, is it just jumping whenever without the RPM's going up at all? Or is it jumping with the RPM's? If it's just the tachometer moving, it's probably a bad ground or a short somewhere. Mine does that right now, but I haven't gotten my engine to run.
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Old Sep 28, 2004 | 09:13 PM
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tach and tachometer are the same thing. measures RPM's. tach is just short for tachometer.

What my tach use to do is bounce around the correct rpms. say if i was at 3000, it would bounce around 3000. Is this what yours is doing? I have no idea what fixed mine. It just started working correctly when i removed my ratsnest.
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Old Sep 28, 2004 | 09:28 PM
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Well, the only reason why I know what my problem is, is because mine does it just when I turn the ignition on. It will sort of wave around too.
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Old Sep 28, 2004 | 09:56 PM
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Usually an erratic tach is due to a bad trailling igniter. Check connections, but you may need to replace that igniter. The trailling one is the black box on the dizzy facing the alternator.

Kent
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Old Sep 28, 2004 | 10:09 PM
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the bad trailing ignitor will also cause a hesitation and a rough idle
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Old Sep 28, 2004 | 10:15 PM
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My tach used to go nuts when I hadn't realized that the plugs on the rear rotor weren't connected (this was when I first got the car)....dunno how the hell that **** happened...

Anyway it jumps a little bit when I'm first idling, but once it warms up she's fine...so I'm cool with it...

My latest thing is a really LOUD vibration sound coming from the rear of the car...it's audible from the inside and out. I'm really hoping it's not something to do with my driveshaft or diff.
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Old Sep 28, 2004 | 10:32 PM
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If the cars shaking, it's probably the drive shaft. I'd check the u-joint first, though, since it would be easiest to check.
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Old Sep 28, 2004 | 10:33 PM
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How much is an igniter?
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Old Sep 28, 2004 | 10:46 PM
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On ebay or on the classified section of this site, you can usually pick up an ignitor for about $15. New they go for $204 from Mazdatrix. Just check around, you should be able to find one. I would also pickup a couple extras if you can in case you want to do DLIDFIS (direct fire ignition) or just to have a spare incase one goes bad in the future.

Kent
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Old Sep 28, 2004 | 10:53 PM
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I also experience a tach problem moving erraticly, it only happens on cold mornings, after the interior temperature warms up , the tach works fine.
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Old Sep 28, 2004 | 10:58 PM
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Erractic Tach

Doing winter mornings I experience tachometer problems, such as slow movement, after cockpit temperature comes up, the tach responds correctly.Has anyone else experience this problem before, and is there a corrective action.
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Old Sep 28, 2004 | 11:05 PM
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i live in an area where it gets to -40 celcius...really ******* cold, no problem with the tach...
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Old Sep 29, 2004 | 07:29 AM
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I had a jumpy tach problem, the cause was my alternator. It wasn't charging at the right RPM's and when it did charge it was hardly giving any current at all. This screwed up the electrics and caused the tach to jump erratically.
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Old Sep 30, 2004 | 02:18 AM
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WTF...the tach stopped doing the jumpyness today....what the hell.....i wonder if it was a "hiccup" of some sort.....itrs running good now.....
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Old Oct 1, 2004 | 08:50 AM
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What is going on??? Now my tach is acting up again plus my car is hesitating like a ****.....what is the first thing i should go do...replace spark plugs...or just go get a damn new ignitor?? And does anyone have any extra ignitors that they can sell me??
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Old Oct 1, 2004 | 10:10 AM
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Sounds like a loose connection somewhere, considering it was fine one day and jumpy the next. I've heard ignitors tend to last 50 years at least with no problems... I'd be looking for a loose ground.
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Old Oct 1, 2004 | 03:23 PM
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my tach went crazy, and it too was from the alt.. i replaced it and BAM!!! all better. but i didnt have any hesitation when driving or idling.
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Old Oct 1, 2004 | 06:58 PM
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Ok now not only is my tach jumpy as hell...my car is hesitiating like there is no tommorow........i have had catalytic converter problems in the past but i fixed (more like unclogged it) before but that was a while back....do you think a clogged converter could have something to do with this......i mean the hesitation bad now....like when i hit the highway, i cant even floor it or its starts bogging down......Could it be my alternator causing the carzy tach jumping, my car always reads like 13 V.....man it sucks because this is my daily driver (and it sucks because i love drving this car but i dont love driving it right now)
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Old Oct 1, 2004 | 09:27 PM
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