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#1
03-21-2005, 07:16 PM
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No Tach instructions have helped me
 Im trying to put a Sunpro tach in my 00 dodge neon, and everythings all hooker up, the only problem is that the RPMs are about half of what they should be. I checked their website, and they didnt say that i needed an adapter, but I dont know what else to do. The tach wire from the tach is connected to 1 of the 3 wires coming from the 1 cluster from my distributor cap. Ive tried all three wires. If anyone can help, thatd be great.
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#2
03-21-2005, 07:36 PM
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Re: No Tach instructions have helped me
there is a switch on the back has setting for 4, 6, 8 cylinders. if it is set on eight it would make sense that it would divide your signal in half.
__________________
2005 cavalier 2.2 ecotec, getrag 5 speed, razzi kit.  http://www.cardomain.com/id/nickelfish19
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#3
03-21-2005, 07:38 PM
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Re: Re: No Tach instructions have helped me
Quote:
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#4
03-22-2005, 06:59 PM
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Re: No Tach instructions have helped me
try the neon forums there smart one..
__________________
Please don't PM me with your J-body Issues. Post appropriately in the forums, and I will toss my opinion in your thread if I have anything to help. - Thanks! 2006 Chevrolet Trailblazer 2010 Glastron GT 205XL
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#7
07-18-2007, 04:47 PM
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Re: No Tach instructions have helped me
the reason that the tach u bought isnt working is because there is no tach wire for a your neon if its anything like my 2001 neon, i tried to hook mine up yesterday and it did the same thing what u have it hooked up to now is the fuel injector wire so that is what its reading currently
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#8
07-29-2007, 12:09 PM
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Reason why aftermarket tachs dont read correct RPM..
I Think I Know why the tachometers only read half of the real RPM. The aftermrket tach was probably designed for a car with a distributor. In that case there would be 4 ignition 'pulses' to count per each two revolutions of a 4 cylinder engine. But the coil pack on the Neon is really two separate coils in one unit. And each coil is only fired 2 times per each two revolutions of the engine. It might be possible to connect Both of the 'signal' or 'trigger' wires going to the coil pack to the tachometer input: BUT, there would Have-To-Be a diode included in each wire - in series- to isolate the two halves of the coil pack. The diodes would let the tachometer see both pulses from both coils, thus four ignition pulses; without fouling up the signals from the PCM. (or destroying it)
Most diodes will have a painted band around the 'cathode' end. This is the side that I would run to the tachometer. The 'anode' end would be connected to the wire running to the coil pack. (If the tach didnt show anything I would reverse them.) Two 1 amp diodes would be good enough, but I would use diodes that had at least a 400 volt PIV rating: Because there would probably be a good sized inductive 'spike' on the wire to the coil pack. For my Neon I bought via ebay.com a replacement instrument cluster with a tachometer in it. The wiring for that tach was already in the harness for my Neon - a 1997.
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#9
07-31-2007, 12:13 AM
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Re: No Tach instructions have helped me
i dont think my instrument panal has a tach wire in its harness because i tested every connection with a multi-meter and had no luck finding a connection that was anything like a tach. But thanks for all ur input i am going to try and do this when i get home from vacation. i want it to work but then again id like to go to the autozone guy who sold me the tach and rub it in his face i was right and he was wrong lol
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