Dakota Digital Tach Adapter work for RB25/S13?

[exodus5547097]

Dakota Digital Tach Adapter work for RB25/S13?

[l0nestar]

... Ask Darius...

[l0nestar]

*edit*Maybe, do you have an SOHC or DOHC tach?
Modified by l0nestar at 9:28 PM 3/26/2008

[Darius]

mmmmmm I don't know. Ask CarlH. For some reason when I was helping a buddy wire his S13, his tach wasn't reading the signal from the ECU at all so there was nothing to calibrate. The S14 tach can be manually adjusted on the back of the cluster. Or if you don't want to pull the cluster like me, you buy a tach signal modifier.

One thing about the signal modifier is that it is somewhat slow in its conversion. cdorhout was hitting the rev limiter before the tach was getting there.

[l0nestar]

Well then, I stand mistaken!

[Carl H]

sohc s13 tachs cannot read the rb signal without modifications, dohc will read but not correctly...I've modified both to work before.not sure about the signal converter.

[l0nestar]

sohc s13 tachs cannot read the rb signal without modifications, dohc will read but not correctly...I've modified both to work before.not sure about the signal converter.

I skipped the glaringly oblivious question... I'm tired.

Somebody revoke 5 'RB points' from me..

I'm off to bed...

[HPF Chrisk]

My dohc tach does not move at all and the shop said that they had wired it and that there is signal all the way from the ecu to the female side of the cluster harness but then no signal from the male side of the cluster harnes out to the tach, the problem is they tried using 2 different cluster harnesses and nothing changed between the 2

[Shocker]

Back in the day I just sent mine to LS auto, it was like a $100, but its spot on with my microtech reading, and is instantaneous just like it should be. Its also 1 of the two gauges that actually work on my whole cluster lol.

[ST240]

sohc s13 tachs cannot read the rb signal without modifications, dohc will read but not correctly...I've modified both to work before.not sure about the signal converter.

Can you elaborate please?

[ralphie!]

i didnt ever have a problem but i decided to make a custom gauge cluster. with a 5 inch tach 3 inch speedo 2 inch fuel,water,oil,and i even had room for a boost gauge

[Bwana]

Carl, mine is still reading a solid 30-40% high but I'm way to lazy to pull it...

[gomer23]

I just put a 10k ohm resistor on the back of the DOHC tach and it reads pretty close to what my SAFC read when I had it. But if your DOHC tach isnt reading the signal its either wired wrong or its been fried because it should read something.

[bauchrb]

my sohc does read... But it only reads like 33% of what it should. Has ever since I did the swap. I just use an Apex'i RSM for tach and speedo.

[meet07]

this whole tach thing is a pain with the rb25. Someone just said that there sohc tach reads something and then others say it reads nothing at all??? I originally had a sohc tach that doesnt pic up a thing. Then I had a dohc tach that was no good. Whats next......get a new tach and try it out?? The pain in my backside..

[Carl H]

if a dohc tach does not read then your wiring is wrong...

[johnny butt]

Can't tell you why your tach has no signal, but when you do get it...I have a 93 S13 (dohc cluster.) with an Rb25DET S1, and we recalibrated the tach like this:

Tach Recalibration:

1. Pull Cluster2. Remove Backing and Clear plastic cover for the gauge.3. Take a sharpie and mark where the needle sits on the gauge face so when you're pulling the needles off you'll know where it sits so its not screwed up when you put them back on, you can also mark the spot it sits on.4. Remove the gauge faces.5. Where the tachometer face is... there is a variable resistor that you can stick a screwdriver in.6. Usually you turn it all the way to the left.7. Once you've done that, do this entire process in reverse order.

You can test the accuracy with a SAFC or some other monitoring device. (my boost controller had a tach feature).

Mine is almost perfect at idle, quick to respond, and when driving it is maybe 25-75 RPMs different from what my boost controller is reading.

[Neejay]

Oh wow, I'll take "25-75 RPMs different". That's not as big of a deal as long as you aren't at redline all the time.

I'll test this out, as my swap is in the process of being done. Thanks a lot man!

[Carl H]

i really hate to break it to you but that has been shown numerous times that it does not work well at all.there are several other factors other than pulling apart your tach and maxing out the potentiometer.

[Neejay]

i really hate to break it to you but that has been shown numerous times that it does not work well at all.there are several other factors other than pulling apart your tach and maxing out the potentiometer.

Figured it was too good to be true. Oh well, I'll be in touch with you again soon Carl. Within the next few days, actually.

[johnny butt]

i really hate to break it to you but that has been shown numerous times that it does not work well at all.there are several other factors other than pulling apart your tach and maxing out the potentiometer.

Which is why I still keep my boost controller showing me RPMs so I can double check and find out how off it is and under which conditions. When accelerating quickly/under boost, I have maybe had about 100rpm difference max, but I don't get anywhere near redline so it's not like that 100 RPMs is going to break my engine.

Taking into consideration that trying it this way is free (as opposed to a ~50-75$ autometer tach), I have not had any discrepancies other than the 25-75 difference [shifting gears/cruising, 100RPM difference under boost acceleration, etc] (cluster tach reads higher), for at least a tank of gas (can't tell you how many miles, my odometer doesn't read right. ). If it makes any difference I have been driving it to and from school and work for a good 2 if not 3 weeks, no problems with the tach, and I am still on a quarter of a tank of gas because I have been driving it easy and shifting before I get to 3000RPMs, maybe a bit over. .

Granted, I think it took a couple of tries to get it close, so you'll have to play around with the potentiometer (that's what LS auto or anyone else will do anyway), but I have not had any problems as of yet.

Also, if anyone wanted to know, I am using a HKS EVC 6 Boost controller to tell me RPM output. At idle after warm-up it sits at about 900, and my gauge cluster tach sits on the same.

And also, from what I have read with the 180SX cluster and all, and getting it to read the MPH speed right, the process works similar: just adjust a potentiometer and check calibration.
Modified by johnny butt at 1:47 PM 11/11/2008

[Carl H]

i think you'll find that your boost controller is set for a 4 cylinder...1k idle hot is what a 4 cylinder tach will read with the 6 cylinder engine.remember that real rpm is 1.5 times higher on a tach setup for a 4 cylinder and with the rb engine idle is normally 6-700rpm.for example 650 * 1.5 = ~975...

[johnny butt]

i think you'll find that your boost controller is set for a 4 cylinder...1k idle hot is what a 4 cylinder tach will read with the 6 cylinder engine.remember that real rpm is 1.5 times higher on a tach setup for a 4 cylinder and with the rb engine idle is normally 6-700rpm.for example 650 * 1.5 = ~975...

Yeah, I've done the math which is why I can say it's reading fairly accurately.

Also, the HKS Evc 6 has settings for 4, 6 and 8 cylinders. One of the first things I did when setting it up was this:

Units for Boost -> PSILeast Boost - > 7.0 PSICylinders? -> 6

Also, with AC and a CD player/ all lights on 900 sounds reasonable.

It does go to 700 when I am just sitting, CD player off, HVAC off, and electric fans not going and I am not turning the steering wheel.

I'll take videos one day if I really have to, but I still don't understand why someone would want to spend 50-100$ for a service you can do in less than 30 minutes yourself.

[Carl H]

im all for people doing it themselves but ive just seen time after time now it not work...numerous threads about it.stock idle is around 600 so i guess if it works on your car thats great but i think if you put it against consult you'd find its reading high.

[johnny butt]

im all for people doing it themselves but ive just seen time after time now it not work...numerous threads about it.stock idle is around 600 so i guess if it works on your car thats great but i think if you put it against consult you'd find its reading high.

The guy I had do my wiring and swap locally tuned while checking everything with consult.He is the same guy that calibrated my tachometer once I read up about it a little more.

For the time being it works, and is a temporary solution until I get enough gauges gathered to make a new cluster anyway.

[Carl H]

all i can say then is you have a fluke, i have never seen anyone get an accurate tach out of that method.

[rb25det250sx]

yeah i know old post, but it worked for me!!! matched my autometer tach EXACTLY!