I always hear, and have witnessed first hand, the inaccuracies of stock guages...especially the oil psi and water temp guages. Where does this inaccuracy stem from? Is it in the mechanics of the guage it's self? The sensor? Wiring? ECU? Could something be done to fix them to be as accurate as hgh dollar aftermarket guages?

 

Because a $10 (cost to build) gauge does not compete with a $50 or $100 aftermarket gauge.

 

Kind of off topic, by why can't the speedometer keep up with high levels of acceleration? Is that common in a lot of cars?

 

You can't tell me that those aftermarket guages cost $50~100 to build. An HKS boost guage, for example, cost in the $100~150 range. Giving that, HKS is making very little profit off of that guage alone. There's got to be more to it than that.

 

my speedos have always kept up fine. There's always going to be a little bit of lag in there because of the way a speedo works. Thinkof it like this...know in those space movies where they have the potential astronauts blow into the tube and lift the little ball up so high? Kina the way a speedo works...but with gears instead of some astronaut blowing on one end of your speedo cable....

 

Nope the typically mark up from cost to sell is round 200% for automotive electronics.

So a gauge that sells for $150, typically cost around $50 to make.

So it is 5 times more expensive to build that the stock gauge. That means probably also 200% more accurate.

Add in the factory idiot factor (the factory wants the gauge to respond slower and less accurate so that the idiots driving the car don't panic at a momentary climb or drop of the gauge) and 100K miles and you have a rather mid-level gauge, when comparied to the aftermarket gauge.

I personally don't think the stock gauges are that bad and are a hell of a lot more accurate than most cars.

 

Mine can't keep up under full-throttle acceleration. I can litterally be slowing down after acceleration, with the speedo needle still rising.

 

That is, by far the most, unique explanation I've ever heard for a gear reduction drive...

LOL

 

if and only if astronaut = girl.

 

and if that speedo cable was my *****.

 

The speedo is mechanically driven.
There really should not be too much error in the entire system unless the speedo cable is binding and parts are slipping.

The water temp gauge is electrical.
OEM automotive engineers have figured out that people panic when the water temp gauge is too high, thus those displays are meant to be rather "dull" in the middle ranges.
They are only meant to tell you DANGER when the needle goes straight up.

The oil pressure gauge is okay, but the sensor is prone to fail due to the vibration and heat of the engine.
If the oil pressure sensor is good, it works pretty accurately.
But, keep in mind the oil pressure gauge is also electrical.

In general, electrical gauges can be designed to display whatever the engineer wants.
A good example is the gas level gauge, where the middle ranges change drastically but the LOW end drops very slowly.
This gauge display is designed on purpose to do this, cause if it really displayed a linear characteristic, most consumers would run out of gas too quickly.


-Ted

 

If you're bitching about aftermarket gauge prices, both Autometer and VDO make great low-prices gauges.
Most of the mechanical stuff should be priced between $20 and $70.
I don't care too much for Autometer boost gauges, but the rest of them are fine.
I prefer VDO gauges myself, as they are a bit more understated in styling and gauge face design.


-Ted

 

The stock s4 gauges are bimetallic strips,..pretty consistant but very slow to react..

 

I use HKS guages. Mark mentioned price. I mentioned an innacurate guage...which the "panicked consumer" response does make sense. Shame though.