Hey guys.

Went out in the car to goto Uni and the tach needle never sat still the whole way! It was jumping up and dowm when driving and when idleing but the engine RPM wasn't changing.

Also, sometimes when I turn it off I can make the needle stick in a position then if you turn the ignition on (Without starting the car) the needle drops.

My only thought is that the cable is maybe gunked up with a lot of crap or broken somewhere.

Anyone have any ideas what's going on as this is beginning to get annoying and I've only donw about 30 miles in it.

Thanks for the help guys

Rob

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1987 IROC-Z Auto (LB9)
Black/grey with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods:
K&Ns
RAM Air
New Underdrive pulleys-either March performance pulleys or Auto Specialties Performance
Air foil

 

I had the same thing happen to me. It turned out to be a plug wire that was seperated inside the boot cover.

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1986 Black & Gold WS6
Trans AM...The Muscle Car Lives
...Its just not at home at the moment...

www.members.home.net/nosaint/

 

The tach is electronic, not cable driven, so there's no cable to get gunked up, and it's supposed to stay in position when you turn the car off, and fall to zero when you turn the ignition back on.

Try making sure your tach wire isn't getting too close to any of the ignition wires.

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1984 Camaro Z28 Astral Silver w/ 2 1/2" cowl induction hood
Engine: Decked 383 cid 4 bolt w/ oil cooler, 9.6:1 compression, ARP fasteners, 600 cfm Performer carburetor, Torker II intake, Performer RPM Heads, XE268H cam, Magnum roller tip rockers, MSD6AL ignition, Blaster2 coil, recurved HEI distributor
Exhaust: Terminator headers, Custom 3" TIG welded stainless exhaust, Twister muffler
Transmission: 4L60 w/ Corvette servo, .500 boost valve, TransGo 7-CS clutch springs, 700 PKH pump rings, 700-2 reprogramming kit, Borg-Warner High-Energy frictions & bands, 2400 RPM lockup torque converter
Drivetrain: 2.73:1 limited-slip Dana 44 w/ disc brakes
Tires: Front P225/50VR15 Rear P265/50VR15 Eagles

 

What? The tach should always fall when you turn the car off. Sorry though I dont know how to fix it.

 

OK, so today I went out in the car and guess what? It's decided to fix itself. Weird, but I'll check the cables anyway just to make sure it doesn't happen again.

Thanks for the help

Rob

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1987 IROC-Z Auto (LB9)
Black/grey with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods:
K&Ns
RAM Air
New Underdrive pulleys-either March performance pulleys or Auto Specialties Performance
Air foil

 

Scooter and RMK, about the tach not going to zero when you shut the car off. I have a Dealer manual for the firebird and it quotes "Due to its dual-coil design, the tachometer may not return to zero when the ignition is turned off. This is a normal condition and should not be diagnosed as a problem in the tachometer." Anyways my firebird does it and so does my dad's firebird so this part at least is not a problem.

 

mine does that too!..the tach flickers violently and can affect performance too,the car "shudders" an hesitates, all I do is take my foot off the gas and gently reapply the acelerator,problem solved. I have no clue what can do that,I'm guessing the ignition module inside the HEI cap,the tach flicering even touching zero while the engine is still reving indicates some kind of major electrical malfunction maybee a momentary short to ground inside the HEI circuits.wish I knew.