custom 68

iTrader: (9)

I hope this will get some resonces here. First I have searched but not seen this problem. I installed the 5 inch indash tach in the 4 cyl mode. At idle and below 1000 rpm the needle "vibrates" it is just a blur from 500 to 900 or so. It is moving so fast it looks like the needle is 1/2 inch wide. as I pick up the rpm it smooths out anything above 1200 seem pretty smoot. The motor is stock and is not vibrating It does it mounted or not. Any help or do I have a bad tach
thanks
Dave

custom 68

iTrader: (9)

oh yea to add to this this is a 5.3 motor in a 68 chevy pickup (swap) I have used an aftermarket painless harness that has a "tach output" in the harness. I cant confirm the rpm is correct (yet will try to scan soon) but it seems right by ear.
Dave

WS6FirebirdTA00

iTrader: (33)

are all the connections tight? sounds like there may be something not connecting right. come to think of it my friends did the same thing on his camaro.

custom 68

iTrader: (9)

Man talk to your friend Yes everything is tight. It seems to work other than this. It is just anoying after spending the big bucks for the entire autometer setup, but boy it sure looks goooood!
Thanks
anybody else?
Dave

WS6FirebirdTA00

iTrader: (33)

i think his still does it, try to call autometer up and ask them, or summit, they are pretty good at helping out, for me at least. you could also be getting some noise in the system at those low engine speeds. maybe sensors are getting messed with by other frequencies, thats a hard one to chase though

Scooter70

iTrader: (1)

Have you hooked up a scanner to the computer so that you can watch the actual RPM verses the gauge? When I have my laptop hooked up, my idle (commanded to 1100rpm) can vary between 600 and 1200. I think it has to do with the IAC (Idle air control) table of my tune. Are you running a bone-stock 5.3 motor with the 5.3 computer?

custom 68

iTrader: (9)

Matt, I have a scanner ordered and should see it this week and will check it out then, the motor is bone stock 5.3 with a pretty agressivly tuned 5.3 computer.
The idle is not changing or seeking a certain RPM the needle is vibrating or moving so fast you cant actually see it moving it just looks like a wide needle at the low RPMs really strange. I know the idle can change around but that doesnt appear to be the case this time.
Dave

Scooter70

iTrader: (1)

Sounds like the tach signal isn't very clean. Speartech did my harness and labeled one wire TACH so I hooked that one up to my Autometer gauge. I'd make sure that you have a good ground for the tach. Otherwise, I'd try another tach if you're sure that everything else is ok.
-Matt

custom 68

iTrader: (9)

Matt, I will double check my ground I am sure it is good but everything must be grounded good to work correctly as I have found. I take it yours is solid except for the actual idle movement (minimal)? and your is setup as a 4 cyl?
again thanks for the input guys
Dave

George F.

I put in the same tach for my 5.3L conversion, and spoke with an Autometer tech on the same issue. They have to recalibrate it, which they will do for free if you send it to them. They will also put a redline mark on it for you if you ask nicely

PM me if you need a contact at Autometer.

Scooter70

iTrader: (1)

Yup. Mine's ok. Looks like George F. may have found the problem.

custom 68

iTrader: (9)

Thanks George, I will PM you.
redline ? I didnt know these things had a redline What is the mark is it just something they put on the inside?
I wonder why some work and some dont? Is it a truck thing...
Thanks
Dave