tacho problems
#1 _T0rana_
Posted 31 January 2006 - 04:28 PM
we installed a Autometer tacho into my uc torana and wen the car is idleing and going at low rev's the tacho jumps around Alot. could it be in the tuneing/coil ?
my engine is a red 6 with commodore electronic dizzy and standed coil.
#2 _draglc_
Posted 31 January 2006 - 09:33 PM
#3
Posted 31 January 2006 - 10:06 PM
#4
Posted 01 February 2006 - 12:18 AM
If the module in the dizzy is in it's death throws, the tacho will bounce.
RACV MAN
#5 _devilsadvocate_
Posted 01 February 2006 - 05:16 AM
Rodomo's suggestion about the module also has merit, if you can get hold of a loaner module or swap over a whole electronic dizzy you could establish whether that is the concern. Ive experienced that one directly, car still ran fine, but module was putting out little spikes that interfered with tacho.
#6 _draglc_
Posted 01 February 2006 - 07:11 AM
A1
#7 _Keithy's_UC_
Posted 01 February 2006 - 10:25 PM
I also have an in line resistor in mine (petentiometer), to sort the electronic dizzy electrowave problems, so that can be ruled out also.
I would check your coil - i think mine is on its way out, so ill get a new one and see how it goes.
Keith
#8 _greenmachine215_
Posted 02 February 2006 - 10:03 PM
#9 _draglc_
Posted 02 February 2006 - 10:39 PM
A1
#10 _Keithy's_UC_
Posted 10 February 2006 - 06:30 PM
I have a petentiometer in mine, im telling you now that its useless... You can adjust it til the cows come home, it does not stop the jumping. I just replaced my Coil, Dizzy cap and Rotor button (the leads and plugs are also brand spankers), and it slowed down the jumping, but its still there! It stopped the flat spot i have with my car, so im going racing soon and aiming for 14's...
Keith
#11
Posted 16 February 2006 - 03:28 AM
For most high performance tacho's (tachos RPM range greater than 8000) a little jumpiness at idle or low revs is quite normal.
Now is time for me to put the flame suit on...
Let's face it, if you bought the tacho and are using for its intended purpose, who really cares what the engine is doing at idle or low revs anyway. You want a tacho that responds fast and operates smoothly in the high rev range, when is important to know and when it counts.
These high performance tachometers are designed with this is exactly mind and as a result of their design there exist a trade off, jumpiness at low revs for superoir high rpm performance.
Cos she's special!!
I have a petentiometer in mine, im telling you now that its useless... You can adjust it til the cows come home, it does not stop the jumping.
Resistors in some instances may help reduce the jumping behaviour. By placing a resistor in the circuit of tachometers that use timing capactiors you can affectively change the RC time constant which has a filtering effect and help reduce erratic behaviour. So potentiometers may not be as useless as you may think if used correctly.
#12 _Keithy's_UC_
Posted 22 February 2006 - 07:58 AM
And as i said before, ive put a brand new ignition system in (from top to tail) and it still jumps.... Must be something to do with the motor?? Earth leakage maybe??
Anyone else have suggestions?
Keith
#13 _ozjason_
Posted 22 February 2006 - 01:06 PM
Firstly, the original poster mentions "standard coil". Standard coil for that car, or standard coil for the Commodore elect dizzy? If you're running the standard coil for that car, I'd try using the coil for the commodore, and see if that improves it. Might have to then remove the ballast resistance from the ignition to match the coil, but that's the way elec ignition is designed to run anyway. A quick test with the original wiring will tell you if that's the problem, anyway. Apologies if I've misread your meaning - you might already have this all set up just fine.
Secondly, you can buy an in-line diode for about $16 from various auto-elect places, that you put in line with the tacho. It stops the jumping and "dirty signal" issues with a points system. It's quite possible it'll help with the electronic system, too. The tachos that came with our red engines had these built in, but modern after market ones don't. A resistor may just dampen the signal, whereas a diode will filter some of the noise right out. (Interesting about the RC mentioned above, though...)
If you're in Brisbane, I can tell you where to buy one. Can't tell you the diode value, as mine came wrapped in heat shrink... can't read the value, but can tell you that it's just a diode soldered to spade connectors, and wrapped in heat shrink.
Just checked your sig - you are in Brisbane. Drop me a PM if you want to test with my diode before you buy one.
Cheers,
Jason.
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