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Adding Gauges - What is Involved re: wiring.

6298 Views 18 Replies 7 Participants Last post by  akirarex
I've been looking at gauges (primarily on ebay), and had some general questions that I'm sure anyone new to gauges would like to know.

1) Source - Is Ebay okay? Any brand to look for, or if it looks nice it'll work? What about 'lit' gauges, not a big deal to wire in, right?

2) Wiring - Many ebay gauges say all the wiring is predone. How hard is it to add a gauge to X sensor/whatever it is?

3) Looking at #2, what Gauges are worth having on a stock car? Oil Temp, Engine Temp, Air/Fuel, Alternator Output?

So... what's involved? Mounting is pretty basic sense, and straightforward, but the above I am curious about.

My particular application is a stock 1990 CRX DX. Thank you for any input you guys have.
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The most useful gauges for a lightly modified vehicle are Voltmeter, Oil Pressure, and Water Temperature. Air/Fuel gauges are just a light show...they don't really give you any insightful information.

As for what brand to get, you get what you pay for. I went with Autometer guages, but there are quite a few other good brands as well.

As for ease of install, anything is easy to install if it isn't done right. Making a nice and clean guage install may be a little more difficult and time consuming, but it is well worth the effort.
auto meter ( auto gauge) and VDO are 2 good reputable companies...

I would agree with Stick...

Oil water and volts are the big 3..
Okay, so if I do those first, how is the installation? Pretty straight forward? I have a Haynes/Chilton, + basic tool set (mechanics 117pc).

Also, why are those the big 3?

I understand oil pressure drop would be important, but you have a light to indicate when it gets too low, does it flucuate often? Good to have an active reading?

Water temp, what can happen?

Volts I understand you can see if the alt is dieing or not charging... =)
A voltmeter (electric) should have come stock and is easily wired in. I wired mine into the fuse box under the steering wheel. Note: every click on the heater blower motor setting takes another .5 volts away. Brake light and headlights obviously make drops happen sometimes.

A tach (electric)should be on all stick shift vehicles in my opinion and is easy to do. I believe all dx crx's have tachs, but not all civic hatch dx's do.

Fuel pressure (mechanical) gauge (installed in the engine bay) has been quite handy to find a dead fuel pump and to change fuel pressure regulator settings.

I personally think vacuum (mechanical) gauges are necessary, they can show you how much fuel you are using (some cars use a vacuum gauge to show you average gas mileage) it can show you the condition of your valves and it is quite necessary if you do ecu tuning.

I used the air fuel ratio meter (electric), and even though it is not an accurate measuring system, I used it to see relatively what was happening to my o2 when I used different chips, and on a few occasions it did tell me that I had to make the car go lean for a few seconds before it would run in closed loop operation, or else I would be open loop the whole way. I also used it to show me when my o2 wire was disconnected on my header because I found that some ecu's could not tell me if the o2 had a fault even with the wire hanging in the air........ long story short on a stock car all you will see is when you start it up it will show full rich until the sensor heats up and is at operating temp, then you will see it dance back and forth from rich to lean to rich to lean over and over.... that's it.

Since I am a gauge whore, I can tell you that oil temp is probably not necessary because oil and water temp (electric) usually run within 5-10 degrees of each other, oil being the hotter. Turbo being the only case where oil temp is necessary in my opinion. Oil pressure is probably more important, and you have one (a sucky one-dummy switch not gauge) on your stock engine as it is.

Any gauge you buy is not going to allow you to simply attach it to a stock sending unit, you are going to have to use "t's" or incorporate the sensor into the system somehow.

Lit gauges are nice, and easy to wire in, take the power from the fuse box under the steering wheel ... find one that is switched on with your lights, I also put a toggle switch on this so I could turn the lights out on my gauges.

With all of this in mind though, has anyone seen what Synoptic has done with ecu control and the autometer gauge panel?
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Stock oil pressure switch is a rediculously low psi rated switch. So your engine is like dead before the switch trips. Oil pressure does fluctuate between 15-20 psi at idle and up to 75 psi or so at high rpms.

The stock water temp gauge does not react in the center of the scale until it goes outside a band of temperatures ...... it is to show a stable temperature, not an accurate temperature reading....... just like the narrowband o2 sensor's abilities, it's for relative use only. That is also why there is no numerical designation on the display just a C or H. With a good aftermarket water gauge you can see your thermostat working or when your fans start working.

You will probably need some extra wire and a multimeter or test light besides a basic tool set. Mounting the gauges will be another issue, pods or cups or custom.
I have a ton of 18ga wire, crimping tool, and ideas where to put pods/cups or a custom location...

I see Autometer (auto gauage) and VDO are top. Are the ebay regular 'lit' gauges to be avoided? You get what you pay for... hmm, any good retailer for those above gauges. I do not mind cutting and T-ing into wires, but will they come with instruction as to which wires for my particular CRX to cut into? Or do I post? Or try to figure it out from a wiring diagram? =)

*edit* has better prices on VDO and Auto Meter (well, for the 'normal'ish gauges) than Ebay does for their unknown ones... =D

What is a sender used for? The gauges I am looking at say no sender required (depending on gauge function), just curious what a send has to do. Also, they called it a T-Bulb, is that the same thing as a wiring T? Can I make the T or do I have to buy it?
I bought all my autometer gauges at summit racing just because it is close to me. Autogauge is the generic gauges of autometers line, wasn't impressed with those at all.

When you buy a good aftermarket gauge you get the dial (gauge) and the sending unit. The sending unit is the sensor. You will have to know if you want mechanical or electrical as well. You cannot use any stock sending units on your car with a gauge, they don't have the same range values at all (most of the time). In my opinion if you buy a gauge that works on stock sending units it's almost pointless, because you could just put a multimeter on your dash and look at any sensor you want to all day. Aftermarket gauge/sending units are much more accurate anyways. So you will have to purchase your own t's and fittings to plumb things in. The gauges come with "typical" instructions, not for your car at all. You will have to figure out all the wiring for power, ground, and lights all on your own or ask here. It's not really that hard.
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I was looking at Autometer's site. I like the Sport-Comp II but will probably paint the rims black.

Also, it is much more expensive but it looks like the 270 degree full sweep electrics are more accurate than the short sweeps. If I go to the effort of mounting mine in the yellow region below, I will go with the full sweep.

I also like the idea of a small switch to turn off the gauges:

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Has no one done a how-to on installing X Y or Z gauge?
I have a 270 degree water temp gauge and I love it. It will take up a lot more space because of the electrical box. The light switch is a must if you drive for a long time at night, it cuts down of fatigue.

I don't think many people have done write ups but I know there is a proper way to tee off the block to do oil pressure, without a "t" mounted on the back of your block. A lot of turbo people have this info. I know the thread for this port is 1/8 british pipe thread, not american pipe thread.
akirarex said:
I have a 270 degree water temp gauge and I love it. It will take up a lot more space because of the electrical box.
Would it still fit in that yellow area I show above? I think they look slick there.

akirarex said:
I don't think many people have done write ups but I know there is a proper way to tee off the block to do oil pressure, without a "t" mounted on the back of your block. A lot of turbo people have this info. I know the thread for this port is 1/8 british pipe thread, not american pipe thread.
Larry did this:

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And can anyone identify those gauges?
Charles said:
And can anyone identify those gauges?
Megan Racing makes them. Definitely a nice looking set of gauges, but for the money, I would go with VDO's vision series.
Hmm... Do I go for flashy or plain?

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I don't know if a full sweep would fit in there, aren't they 2 5/8" not the normal 2 1/16"? I can't remember if they make full sweeps in the smaller size. The only thing about full sweeps is that the electric converter box which has long wires needs to be put somewhere, it doesn't have to be that close to the gauge either so it can be put kinda wherever you can hide it.
I believe the general rule is that full sweep gauges are mechanical and the elec not (at least Autometer is that way)
My set up: 2 1/16th elec water & volts(duh) and mech oil press
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The rule for autometer's full sweep is just that they are expensive (120 dollars) electric gauges. The only mechanical gauge I use is vacuum. They do come in both sizes. ... =11&opId=1
Ok I just did some test holes in a 89 crx dash, 2 5/8" gauges really are just too big to fit in the dash, it cuts a lot of material out and looks like it's too big when it's in there.... 2 1/16" is definitely the way to go for the dash. I just cut 4 holes into my dash on my hatch to put my gauges in there, using a 2" hole saw. I like them in the dash more than on the pillar. Although the pillar has a better angle to view the gauges. If you are going to cut the dash up take into account the viewing angle a.k.a. drilling angle.... but I think autometer sells angle rings for like 8 bucks to get the right angle for your gauge. It's not really that far off though. One other thing to take into account with gauges is the reflection that you will see on the windshield. I use the ultra light series which has aluminum rings and background which reflects quite a bit. A black matte finish would be ideal for the trim ring.
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