Temperature Display as LDA? Misuse?

Hi everyone,

As I was sitting in the car during my lunch break, eating my sandwich (an interesting rhyme ), I had the idea to repurpose the temperature gauge as a boost pressure gauge. The scale already fits quite well. 90°C corresponds to 0.9 bar of boost pressure, and 130°C corresponds to 1.3 bar of boost pressure (the rest is analogous to that). In the newer models, the scale is even quite linear.
I've read several times here that the temperature display is controlled by the engine control unit (ECU) and not directly by the temperature sensors. The question now is, what format is the signal from the ECU to the display?
If it's an analog signal, it should be relatively simple to adjust the analog signal from the boost pressure sensor so that it can be used for the display instead of the 'temperature voltage.'
A small switch then handles the switching between temperature and boost pressure.
What is your opinion on that?

Greetings.

Eike.

Hi Eike,

Do you know Radio Eriwan? Basically, yes, but...

I'm not familiar with your car, but it's possible that you only have one temperature sensor for the engine, and your engine control unit (ECU) reads the engine temperature from that sensor. So, that's not how it works, but...
(That's likely the case if your temperature signal is coming from the MSG.)

If you modify the cockpit, remove the wiring for the instruments, and use an operational amplifier to correct the degraded boost pressure signal, then it might work (assuming you haven't already replaced the coil instruments with stepper motors).
I like the idea and I'll check it out myself when I have time; it might be something useful for my 'tips and tricks' collection.
After installing the oil temperature sensor (which is more important than the block temperature sensor in normal operation), that would be a great solution, and I could remove the modified air pressure fitting.

Hi,

I consider it almost hopeless. The display is implemented using stepper motors, and on top of that, there's this ramp function that makes a simple representation impossible.

Ultimately, this would result in a complete overhaul.

I'm currently working on a digital LDA (Laser Doppler Vibrometer) that functions similarly to what Rainer described some time ago, but uses an independent sensor. I'll write more about it when it's finished.

Best regards,

Jan.

, but using an independent sensor. When it's finished, .

Why is that?

The original is linear, just tap it and it's good .

CU Gremlin.

Hi Gremlin,

I want to be fault-tolerant. You won't detect defects in the original sensor that way, and there's also the risk that the additional circuit might introduce some interference into the system. Therefore, I want to build something completely independent, using an MPX4250AP as a basis. It's also linear }.

I wouldn't be surprised if it's also included in the original parts, as Motorola explicitly mentioned "automotive" in the datasheet.

Best regards,

Jan.

No, the Bosch sensors are custom-made. At least, the micro-mechanical ones that are currently being used.

CU Gremlin.