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Old 30th December 2007, 09:05   #1
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Default Problem with my Aftermarket Tachometer

Hi guys,

Picked up a Tachometer for my Esteem about an year back, I have 2 queries regarding its working,

1) The needle seems to have bent and it goes below 0 Rpm when the ignition is turned off. Can this be rectified?




2) There is a RPM lag difference between the Car's original Tach and the after market one ( I know its really silly to go in for a tach once the manufacturer has provided, still i got this after market one for very cheap in Dubai, thus it was bolted on). Can this problem be rectified? any suggestions?



Would appreciate if i could know where in Bangalore i could get help to solve this issue.

Ride safe
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Old 30th December 2007, 09:30   #2
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answer to question 2.
after market tacho shows more accurate reading.
question 1
my tacho too shows weird reading when switched off..but when ignition on, there is no problem. so may not be a problem at all.
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Old 30th December 2007, 09:33   #3
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Quote:
Originally Posted by kutlee View Post
answer to question 2.
after market tacho shows more accurate reading.

.
Huh,How would that be? I thought the aftermarket one has to be calibrated to match the OEM tacho. Which is more or less accurate.
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Old 30th December 2007, 09:59   #4
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1. No issue. Happens often.

2. What does your tacho show at idle, at 100 kmph in 2nd gear, and at 100 kmph in 5th gear? Using these, calculate your true rpm using your gear ratios, and you should know which one is more accurate.

No, tachos don't have to be calibrated.
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Old 30th December 2007, 14:42   #5
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Quote:
Originally Posted by redrage View Post
Huh,How would that be? I thought the aftermarket one has to be calibrated to match the OEM tacho. Which is more or less accurate.
No, calibration is not required.

The tacho picks up the signal from the ignition and hence needs no calibration. If it picks up only one cylinder then nothing is required to be done, if multiple cylinder inputs are used (can be a pain with distributorless ignition) then there may be a switch to select no. of cylinders. X pulses mean 2X (or X/2) revolutions.
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Old 30th December 2007, 17:07   #6
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ok.So what do i do to make the tacho's run at the same RPM?
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Old 31st December 2007, 05:05   #7
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U know these after market tachos have this problem a couple of months down the line..

Firstly the needle going below zero when ignition is off is a normal thing with every tach so nothing to worry about..

Secondly there are level 1 and level 2 tachos.. If yours is a level 2 then u got the wrong one coz no indian cars are made for them or vice versa.. Indian cars can only use level one tachs.. Thats why always make sure u get the original branded ones.. Don compromise on accuracy just coz u get these for a lesser amount
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Old 31st December 2007, 09:44   #8
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Can you please explain what is Level 1 what is Level 2. Is it the same as class, which means accuracy of 1% or 2%?
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Old 3rd January 2008, 11:32   #9
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Hey, even my tacho has a problem. There's a sort of delay after revving. The needle moves only a second after I press the throttle. The car is a Corsa nad the Tacho is an Autogauge 5". Can anyone help me???
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Old 4th January 2008, 14:34   #10
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Guys ,as Adman addressed can this delay in revving be corrected? I.e. Both the tacho's be made to display the same?
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Old 4th January 2008, 16:59   #11
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It will be tough. I suspect that while the after market tacho may use a proper Frequency to Voltage converter, the OE unit uses essentially

Pulse Shaper > RC Network to Charge Capacitor + RC Network to Discharge Capacitor; with a display of the capacitor voltage for the rpm.

Someone will have to get into it with a pulse generator and then try and calibrate it. easier said than done! Remember in some areas car displays are (or at least used to be) Class 20; i.e. 20% errors either way are allowed. Fortunately speedos are not!
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Old 6th January 2008, 16:02   #12
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ummm....China problem...
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Old 6th January 2008, 16:57   #13
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Quote:
Originally Posted by speedfreak7116 View Post
Secondly there are level 1 and level 2 tachos.. If yours is a level 2 then u got the wrong one coz no indian cars are made for them or vice versa.. Indian cars can only use level one tachs.. Thats why always make sure u get the original branded ones.. Don compromise on accuracy just coz u get these for a lesser amount
Never heard of this before. Could you please explain further?
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Old 6th January 2008, 17:22   #14
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Quote:
Originally Posted by tony_jtrd View Post
ummm....China problem...
Nope. Dubai problem.
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Old 7th January 2008, 13:35   #15
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ok guys big problem here,,i got myself one of these 60mm tachometer (tach) for safari dicor.
Now the tach sensor wire has to be attached to the ecu wire and safari's company tach is attached to the alternator and not the ecu! ,if i connect the the 60 mm tach to the alternator the reading goes nuts. Plus i checked with the safari dealers and they dont have the ecu color maps.
Can anyone help me to figure out a way to use the 60mm tach in the safari??
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