Ode to the Mustang temp gauge And Factory Owner's Manual

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The stock gage on my 82 clearly told me I was overheating at the track a couple weeks ago. It's the original to the car. Straight up is about 180 on the gage. Never felt I needed other gages.

How did the OEM gauges compare to aftermarket readings or ECT (if applicable on your '86)?



The stock gauges have hysteresis built into them. This is true with most OEM gauges.

Pics of said vehicles?

NikwoaC said:

Pics of said vehicles?

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HISSIN50 said:

The stock gauges have hysteresis built into them. This is true with most OEM gauges.

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Plus Auto Meter gauges look cooler.

ECT = Engine Coolant Temperature sensor. This is the coolant sensor the EEC uses. Using a DMM, one can interpolate the reading.

Unless you are diagnosing a specific problem then the stock gauges are fine. There is no need for anyone to truely know how hot or cold the engine is. Once you establish a baseline temp then all you have to do is watch to see of the temps go over or under. What is more critical then accuracy of the gauge is the consistancy of the gauge. It doesn't really matter if the tach reads 6,000 when the engine is only turning 5,000. As long as the tach is consistantly wrong by the same amount you can use it for almost any purpose including setting shift points.

Maryland Stang said:

Unless you are diagnosing a specific problem then the stock gauges are fine. There is no need for anyone to truely know how hot or cold the engine is. Once you establish a baseline temp then all you have to do is watch to see of the temps go over or under. What is more critical then accuracy of the gauge is the consistancy of the gauge. It doesn't really matter if the tach reads 6,000 when the engine is only turning 5,000. As long as the tach is consistantly wrong by the same amount you can use it for almost any purpose including setting shift points.

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Are you only talking about tachs? I'd agree that they are not all that important on stockish street cars (if needing to know actual RPM, a diagnostic tach or access to the EEC tach-reading is needed anyhow).

I'd disagree regarding the rest. Accuracy in most other gauges is important to many folks, especially if one lives in an extreme climate or does some sort of racing.

HISSIN50 said:

I'd disagree regarding the rest. Accuracy in most other gauges is important to many folks, especially if one lives in an extreme climate or does some sort of racing.

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What difference does it make? If you baseline your gauges you can go from there. A lot of racers clock their gauges in different directions. I asked one of them why they did that. He said the gauges were clocked so all of the pointers would be straight up when everything was normal. If you glance at the gauges and one of them isn't straight up then you know you have a problem.

Maryland Stang said:

What difference does it make? If you baseline your gauges you can go from there. A lot of racers clock their gauges in different directions. I asked one of them why they did that. He said the gauges were clocked so all of the pointers would be straight up when everything was normal. If you glance at the gauges and one of them isn't straight up then you know you have a problem.

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I also used to clock my gauges because there isn't time to look at them.
That has nothin to do with this argument.

Let's say you're out racing at an indicated 230*F but it turns out your temp gauge reads 35*F too cool. Would you have liked an accurate gauge telling you how hot you really were?

Since you like to reference racing, would you use a 99 cent pencil tire pressure gauge to tweek the pressure in your DR's? You can use it to make relative pressure changes, right? Sure, but no one would do it. They use a quality gauge for accuracy and consistency.

HISSIN50 said:

I also used to clock my gauges because there isn't time to look at them.
That has nothin to do with this argument.

Let's say you're out racing at an indicated 230*F but it turns out your temp gauge reads 35*F too cool. Would you have liked an accurate gauge telling you how hot you really were?

Since you like to reference racing, would you use a 99 cent pencil tire pressure gauge to tweek the pressure in your DR's? You can use it to make relative pressure changes, right? Sure, but no one would do it. They use a quality gauge for accuracy and consistency.

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I'm not trying to argue with you, just show you my way of thinking about gauges.

In your first analogy.... If my gauge always reads 170 when I know for a fact the temp is really 205 then that's fine. I referenced setting a baseline. That would be my baseline. It's good at 180. Now if it raises to 205 on my gauge I know that there is a problem. If steam starts coming out of the overflow I also know there's a problem. Gauges that are accurate and consistant are the best of all worlds but for 99% of the people out there a gauge that is consistant is good enough. If my guage only has Low Med and Hot as the references and my car always hangs around between L and M and then suddenly one day it's between M and H I know there's a problem.

For a serious racer you always want a tire gauge with a high resolution. But we're dealing with a critical tuning device where 1/10 of a PSI can make a difference. But even there as long as the gauge is consistant more so than accurate is important. If you set you tires to 15.5 PSI on a crap gauge and the car corners great then that would be where you want them to be. Even though the gauge is inaccurate even though it is consistant doesn't matter. You baselined the perfect PSI on that gauge at 15.5 PSI.

I think what I'm trying to say is it doesn't matter what the scale is. If you were to get into a car with metric gauges, just because they read in metric and you don't know the conversion right off of the top of your head and not standard American doesn't make them any less useful. You only need to know what the gauge means in order to make them useful.

It's just like my Mustang. I had 3.73 gears put in it. The factory gears were 3.08s. I read up a lot before I installed the gears and found out that the 23 tooth gear that should be used for 3.73s tends to strip out real fast. So I left the 3.08 speedo gear in it. The conversion is 1.2. If I take the indicated speed and multply it by 1.2 I'll know what my real speed is. It works like a champ. The gauge isn't accurate to the posted speeds but it is consistant and since I know the conversion it's easy to tell how fast I'm going. Judging from the fact that everytime a cop hears me coming they feel a need to follow me all of the way to the town limits and can't find a reason to pull me over I'd have to say that it works very well.

It's called relativity.

I don't wanna argue either. I understand your point about relativity.

My initial points were that I didnt know people had aftermarket gauges or some other way of knowing how far off their stock gauges were in the first place. If someone knows that, it helps. I thought the assumption was that this was not known and they were relying on the stock gauge being accurate (without any basis for comparison). That's how I read it.

And the stock gauges have that hysteresis built into them. That means it takes significant change for them to move. By design, the stock gauges cannot even give accurate relative-readings with regard to smaller changes in system performance.