Need help w/ Tach install..

[Jdmturbo]

Before i start.please save any criticism or snyde remarks for your girlfriends. Not to be rude, but i just need the facts.

Here we go....

Installed autometer tach and removed old tach/boost guage.

+Pos. wire is spliced into cig. lighter which is reading good voltage on the voltmeter.

-Neg. is grounded to a nut on the stereo/computer brace.

Now the Rpm signal....I checked the pinout on Machv.com-http://store5.yimg.com/I/machv_1783_42853764- and wired the Rpm signal wire to their digram..using the wire from pin #4(#54 on VFAQ) on the 18p connector.

When I turned it on the tach went to 0 from sitting at like 2000....nothing happend.

Next i tapped the signal wire into pin #109 according to the VFAQ pinout-http://www.vfaq.com/mods/ecu-harness-1G.html which is says is "Ignition pulse detect (tach)"

Same thing ...turn ign. key to off and tach goes to 3 or 2..then turn on goes straight to 0..shows no idle. Ive read people hooking to the cam sensor or the filter that connects to the coil...But shouldnt it work they i've tried? The stock tach was working fine previous to removal. Could it be the bolts that went into the stock tach need to need put into the cluster to make a complete curcuit?


PLEASE HELP

 

[spendone]

I have had to luck with the tach, the rpm readings are never right. I get real low rpms with the tach. I had mine hookd up to the tach wire under teh hood.

 

[Boosted19]

try the RPM wire on the ecu harness, its on the bigger clip and is like the 4th one in i belive, and its GREEN. hope this helps.

 

[Jdmturbo]

I tried using that 4th wire on the Big connector...this is actually the Cam sensor wire..still didnt work...im gonna try and put the screw back in the holes for the factory tach and then try the connections again...im thinking these bolts missing is causing and in complete circuit(???).
Ill post the results~

 

[dsmjay]

below the coil pack is a little plug. in that plug is one white wire. thats the wire that you have to tap to get a good reading. thats where mine is and it read perfect. its the only white wire in that plug

 

[ivanr4g63]

^^^ Second that

 

[spendone]

I have it in teher but it never reads right. Ill be at idle reving at 750 and teh tach would only read 200 rpms. I have it set at 4 clynder too. This just got annoying after awhile.

 

[dsmjay]

thats what my tach was doing when i tried hooking it up in different places...what kind of tach do you have? but the white wire on that plug is diffently the place to hook it up. we have 4 of us dsms that run around here and we all have it hooked up the same and ive had no problems at all.

 

[spendone]

Its a autometer carbon fiber tach that I have, It has switches for 4-6-8 cylinders. I just have no luck with it at all. When in up to 6000 rpms the tach only read 3000.

 

[dsmjay]

then you have it on the wrong wire....i had that same problem till we hit teh white wire. and my read out is perfect

 

[91talontsiturbo]

I am really sorry for bringing this back from the dead.
But would their be a 'white wire' in both 90 and 91's+ since thier different?

 

[dsmracer_1991]

Not sure about bein the same on 90-91 but as everyone else has theres hooked up i have also. the white one. i had so much damn trouble tryin to figure it out, then i thought my tach was broken. i just looked for the factory tach signal wire in my haynes manual. waht a PITA, i feel ya.

 

[spendone]

90's had a different type of wiring. The white wire only reads as 2 cyl's. You have to hook that tach up directly to your ecu or get a tach adapter. I actually have a autometer tach adapter for sale if your interested. PM me if you are.

 

[91talontsiturbo]

Well heres my problem: I got a 90 body with a 93 motor, the previous owner wired it all up so it would run ( dont know how he did that as of yet) but the tach's not working and i really don't want to go off splicing and what not for it to work and maby end up making the car not run anymore. So for now (temporary use) i was just wanting to put a external tach in there untill i can find a 90 coil pack with the 4 prong connector and have the original work.

So what you are saying is that its ok to hook up the signal wire to the 'white wire' in 91's+ coil pack but not the 90 since it only reads 2cyl's.

Thanks for not flaming me on bringing this back, i was kinda holding my breath a little as for getting an answer .

 

[91talontsiturbo]

Ok i went out tonight in looked it over agin.
seems as though the guy who owned it before me attempted to switch the coil but didn't?

It has the original 90 transistor but with the 91-94 coil pack

On the 90 coil pack theres a white wire, that should be the 4th wire on the 90's right...

Well the guy spliced the 3 wire 91-94 coil pack wiring harness in with the 90 harness leaving the white wire just hanging there.

Could somthing bad become part of this that im not aware of?
i checked the white wire and what it was for and i guess it goes to the noise filter then to the fuel pump controler?

someone correct me if im wrong cause i might be im not that sure.