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Guest Message by DevFuse
 

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Tachometer?


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12 replies to this topic

#1 EVOthis

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Posted 25 January 2008 - 07:20 AM

ive got a 96' legacy ej22 with a 5 spd. my car seems to be sending the wrong info to the tach in the instrument
cluster....The problem is i can drive the car here and there and than intermittently i see the tach out of the corner of my eye kind of jump up just little bit.....Ill put it this way when this happens my tach is definately still operative but it takes FOREVER to go from 3K RPM to 4K RPM everything else is normal....except the idle is a little bit low (almost unnoticeable) and as soon as i shift it doesnt drop all the way down like it should it may drop half that....ex:im shifting into 5th at 4K RPM the tach my drop down to like 3K instead of dropping like it is supposed to down to like maybe 2K...and the thing is i think my engine is actually running at that speed....which is why it turned me away from the gauge itself........any info on this would be wonderful....thanks guys!:) (is there any sensor that could cause this?)

#2 EVOthis

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Posted 25 January 2008 - 09:32 AM

could like a throttle position sensor or IAC cause this?

#3 Skip

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Posted 25 January 2008 - 11:58 AM

If the engine is doing what the tach says

the IAC may cause it.

So could other things.

I would recco installing an aftermarket tach
temporarily,
watch it and the real deal
and see if it's the tach
(cold grease in the needle movement pivot)
or??

#4 EVOthis

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Posted 25 January 2008 - 12:36 PM

thanks skip.....i will do some testing over the weekend and see what i come up with....my idle is perfect when im out of gear but when im in gear idling it seems low......again ill see what i find when i go over some things with a fine tooth comb....:confused:

#5 Skip

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Posted 25 January 2008 - 03:18 PM

kewl on that,
if you want to try an aftermarket
tach.
I have one I'll lend you for the test.
I'll include the wiring (three wires).

#6 frag

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Posted 25 January 2008 - 04:20 PM

kewl on that,
if you want to try an aftermarket
tach.
I have one I'll lend you for the test.
I'll include the wiring (three wires).


If I have permission to hop on board a bit, I have a digital multimeter with a dwell tach function but it has only two wires.
Where do I connect those two wires to have a rpm reading?
Thanks in advance.

#7 EVOthis

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Posted 25 January 2008 - 04:32 PM

thanks skip...ill have to see becuase for a while i have been wanting to put like a gauge pod in my legacy so this may be the excuse to do that....:headbang:

#8 Skip

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Posted 25 January 2008 - 04:40 PM

Hi Frag, mine connects to the yellow/blue wire
going to the ignitor and ground.

Depending on the input impedence of the MM
when set on the tach setting,
you may need to use
an output wire from the ignitor to the
coil pack.

Wasted spark system fires the plug twice per revolution
so cuting the RPM in half may be ness.

Thanks to Porc73 for the diagram
Posted Image

#9 porcupine73

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Posted 26 January 2008 - 07:08 AM

For a tach hookup, on my '96 2.2L brighton (no dash tach!), I pulled the gauge cluster and traced the wire from the circuit board back to the wiring harness. Then I spliced in there, I think it was a green/blue wire.

I believe you can also tap in right at the coil pack, like to the RG or L in the diagram. That is how the remote start tach signal is connected on my '00obw.

#10 frag

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Posted 26 January 2008 - 11:25 AM

Thanks for the replies.
Old style ignition coils had easily accessible open "screw on" primary connections. Not so with modern coil packs and ignitors. How exactly do you «tap in» those connections without harming anything ?

#11 porcupine73

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Posted 26 January 2008 - 02:54 PM

Hi. Mine is tapped in with those quick splice connectors that like pierce the insulation on the wire. It's not the way I would do it, but that's the way the vehicle came.

#12 WAWalker

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Posted 21 February 2008 - 12:17 PM

This is how I tap into that wire.

Posted Image

I have had to pull a couple of engines that had a tach signal wire for remote start soldered in. No way to disconnect it when pulling the engine, other than unsolder or cut the wires, no good IMO.

#13 EVOthis

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Posted 21 February 2008 - 01:01 PM

is it safe to backprobe the igniter connector with some T-pins just for a few moments while i monitor the RPM at idle?




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