Building a Tachometer for Swift LDi - Team-BHP

vishnugs · 7th May 2007, 15:44

I long to have a tachometer on my Swift LDi.

I have decent experience in building the electronics to get the numbers on LCD, but is there any point which will give the pulses ?

Vishnu

arunforu1 · 7th May 2007, 16:33

Quote:

Originally Posted by vishnugs

I long to have a tachometer on my Swift LDi.

I have decent experience in building the electronics to get the numbers on LCD, but is there any point which will give the pulses ?

Vishnu

I am not an electronics expert, but do you mean a tranducer point which will give pulses for each rotation of crankshaft?

If yes try somekind of motion sensor, on timing pully of crankshaft(i dont know if swift uses timing chain or belt), whatever may be the case belt or chain, the main crakshaft pully/sporket is the ideal location to indtall sensor.

What kind of sensor?...that you have to find out & tell me what you have used, may be some kind of magnetic counter may serve your purpose for transducer, but i dont have details for commercially available one.

Please do ltell me how you did it?

ajitkommini · 7th May 2007, 16:48

Rather than using a motion sensor, it would be better to measure the spark rate using something like an inductive tap on one of the spark plug cables. This is how most commercial tachometers work AFAIK.

elf · 7th May 2007, 17:08

Quote:

Originally Posted by ajitkommini

... an inductive tap on one of the spark plug cables. ...

Err, ajit. Diesels don't have spark plugs or their attendant cables.

ajitkommini · 7th May 2007, 17:18

Right :-) sorry - not enough coffee in blood stream i guess

Rtech · 7th May 2007, 17:23

Buy the Instrument cluster from the VDi. Take yours out. Fit that in. There should already be the necessary hook up for the tacho signal somewhere back there. There ya go. A stock looking instrument cluster.

Technically though I don't think this could be legal as you are essentially "clocking" you car, because your ODO will start from 0km again.

That's the basic. Maybe someone else with a better knowledge of the Swift electrics can assist you further.

Ofcourse, if you want to go the RICE way with a huge tacho that blocks 1/4 of the windscreen, thats possible too.

swathyd · 7th May 2007, 17:58

Tampering with the vehile in this fashion may invite a termination of warranty. So ask your dealer to do this work for you. That will save you from loosing warranty.

Sideways · 7th May 2007, 19:23

Tap the RPM signal fromthe ECU. You will need a wiring diagram of the ecu for this though to verify pin number.

n_aditya · 7th May 2007, 19:26

Quote:

Originally Posted by vishnugs

I long to have a tachometer on my Swift.

Buy an aftermarket autoguage or autometer tacho. Various sizes and designs are available.

Ram · 7th May 2007, 19:39

In the days of the pre ECU diesels, a waveform was picked up from the alternator, waveshaped, scaled and fed to the tachometer.

Ram Rao

7th May 2007, 15:44	#1 (permalink)
vishnugs BHPian Join Date: Mar 2006 Location: Bangalore Posts: 89	Building a Tachometer for Swift LDi I long to have a tachometer on my Swift LDi. I have decent experience in building the electronics to get the numbers on LCD, but is there any point which will give the pulses ? Vishnu

7th May 2007, 19:23	#8 (permalink)
Sideways Distinguished - BHPian Join Date: Nov 2004 Location: Madras - India Posts: 719 View My Garage	Tap the RPM signal fromthe ECU. You will need a wiring diagram of the ecu for this though to verify pin number. __________________ He's Back

7th May 2007, 19:39	#10 (permalink)
Ram Distinguished - BHPian Join Date: Dec 2005 Location: Mumbai, Pune, München Posts: 1,552 View My Garage	In the days of the pre ECU diesels, a waveform was picked up from the alternator, waveshaped, scaled and fed to the tachometer. Ram Rao __________________ When you struggle for something and fail, that’s when you get Experience!

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7th May 2007, 16:48	#3 (permalink)
ajitkommini BHPian Join Date: Sep 2006 Location: Bangalore Posts: 267	Rather than using a motion sensor, it would be better to measure the spark rate using something like an inductive tap on one of the spark plug cables. This is how most commercial tachometers work AFAIK.

7th May 2007, 17:18	#5 (permalink)
ajitkommini BHPian Join Date: Sep 2006 Location: Bangalore Posts: 267	Right :-) sorry - not enough coffee in blood stream i guess

7th May 2007, 17:23	#6 (permalink)
Rtech Team-BHP Moderator Join Date: Apr 2004 Location: Bombay Posts: 5,980 View My Garage	Buy the Instrument cluster from the VDi. Take yours out. Fit that in. There should already be the necessary hook up for the tacho signal somewhere back there. There ya go. A stock looking instrument cluster. Technically though I don't think this could be legal as you are essentially "clocking" you car, because your ODO will start from 0km again. That's the basic. Maybe someone else with a better knowledge of the Swift electrics can assist you further. Ofcourse, if you want to go the RICE way with a huge tacho that blocks 1/4 of the windscreen, thats possible too.

7th May 2007, 17:58	#7 (permalink)
swathyd BHPian Join Date: Mar 2007 Location: thiruvananthapuram Posts: 595	Tampering with the vehile in this fashion may invite a termination of warranty. So ask your dealer to do this work for you. That will save you from loosing warranty.