I'm installing a tachometer

I think the regulars will suggest ditching the tachometer and buying the SGII. You'll get much more bang for buck and you don't need to cut any wires.

 

doesn't look too hard, what tach did you buy and how do you know it's sensitive enough?

 

Not me! An analog needle can be read at a glance, which is important for feedback that you are likely to use often. I look at engine RPM all the time. The digital ScanGauge display is better suited to slower moving feedback that you need less frequently. It's great for things like EV button condition, engine temperature, etc.

I used Hobbit's page as a guide and didn't have any problems. That was four years ago and it still works. My only wish is that I had bought a better-quality tach, though my cheapo does get the job done. Just go slowly and if in doubt, stop and ask for help.

 

Did you explode yet? :madgrin:

 

That is correct.

 

In a car in which the prime mover is an electric motor, what does a tach on the ICE tell you? I understand about the ICE's torque curve and power curve -- so you've got an RPM number for peak torque (acceleration) and peak power (sustaining velocity against drag and hills), I suppose. Except you've got an ECU between your foot and the injectors that has its own ideas about ICE curves. But you have to do your own P&G calculations if you want to do control down to an RCH -- so what does knowing the ICE RPM give you?

I agree about analog displays. At a pilots' organization meeting this week one of the flight instructors said that accident data was showing more crashes in planes with glass cockpits than in planes with old steam-gauge six-packs. (Of course that's skewed by other factors like the aerodynamics of newer planes, which just happen to have glass cockpits.

As far as I know, if you do't have a British car from the 1950s, you are extremely unlikely to have a positive ground. (Don't know about Ladas and Trabants.)

RCH: an engineering term for an extremely small measurement.

 

it tells you the sweet spot for best acceleration gpm's.

 

nice pics. sorry, i don't have any answers, but i'm watching with great interest. be patient, i'm sure some of the techs here will help you out.

 

Sorry for the way late reply. I just wired it to the lighter since I had to run the other wires in that direction, anyway. I have the same tach and it definitely works. Do disconnect the 12V battery before doing the work just to be safe. It might not be strictly necessary but an accidental short across the wrong ECU wires could ruin your day (and ECU). That's one of those low probability but severe consequence type events that you may as well prevent.

Your placement looks good, very similar to mine. You will need to make some kind of bracket, since it comes with something designed for a steering column. If you can fabricate a simple bracket, 3m "Dual Lock" fasteners are the absolute best non-permanent solution that I have found so far. I get it at Target. I'll try to post a pic of my mount later in case you want some inspiration.

Mine seems to be a couple hundred RPM off compared to the scangauge but it gets the job done and hasn't failed. I don't think the discrepancy really matters since you just need a reference.

 

Here are pics of my own install. Like I said, that Dual Lock stuff is great. I fabricated the bracket itself from a sheet of lexan, which is available at your local home store. Just cut out the shape you want (a Dremel or equivalent is helpful here) and make the bend with a gentle application of heat. I like to pass this stuff back-and-forth a few inches over a candle, which I find gives me enough heat and good control. It will reach a magic phase transformation temperature and bend right over. Then just hold it in place for a few seconds as it cools. I'm sure there are slicker options but this was easy.

 

Oh, one last thing. The wires can be tucked behind the weather stripping that runs down the door jamb. Also, I seem to recall needing extra wire to get all the way to the ECU, which is all the way on the right behind the glove box. Tucking all the wires behind the dash will probably be a pain. I don't recall exactly how I did it but I'm sure you will find a path. Zip ties are helpful to keep wires in place.

 

It only goes to 8K ?? Might be ok for city driving...

 

I went out to look and I would have to tear things down a bit more than I want to to get decent pics. But for the ground I think I just tapped the lighter socket same as the 12V+. For all connections the simplest method is to use wire taps. They can be a little finicky if you don't crimp them down far enough, but it gets you out of cutting important wires that you then have to splice back together. Just be careful not to tug too hard on anything while making your connections.

 

Still alive?