DIY EGT display approx $16

Great! I'll check back tomorrow. Thank you!!!

Here is my solution .
I use Arduino UNO, 1,3" OLED I2C screen, Bosch MAP sensor from old MSA15 ECU and BMP180 sensor for barometric pressure correction .
Units is in Bar and temp in °C

Now I'm waiting for 4Bar MAP .

https://youtu.be/GDPUozaQg88

Great, i bet something like this take way more time to develop ? https://www.youtube.com/watch?v=jGiy8lNCCcg

Thanks for sharing, this is what makes the internet great,

3 displays with boost - IAT, EGT- EMP, oil pressure+temp would be awesome. What we need for this kind of project?
This last video is very nice also.

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arazvan2002 said:

3 displays with boost - IAT, EGT- EMP, oil pressure+temp would be awesome. What we need for this kind of project?
This last video is very nice also.
Sent from my HTC 10 using Tapatalk

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I am going to this this setup with my Ford Ranger with a 2001 ALH Installed in it.

The instrument pod has a blank panel that the automatic P N R D 1 2 3 thing is supposed to go into. A 16x2 LED display fits there nicely.


EGT 950 TRB 1.7
IAT 55 OIL 137


There is enough info there to give me what I want - Exhaust temp, Oil Temp, Intake Temp, Turbo boost.

This would be easy work for an Arduino - "051 C" MAP sensor for the Boost and IAT, regular restive oil temp sender and a thermocouple for the EGT.

The nano has sufficient inputs for the 3 analog inputs for boost IAT and oil pressure. The EGT using the max6675 used 3 of the digital inputs. I would have to test simple code to see if there is even enough memory space for all 4 inputs. I prefer the u8g library as it has better looking fonts that are not so block styled. The adafruit library is ok too.

Libang-Is there a DIY anywhere on how to do this for guys not into electronics like you an AKnovaman? It seems this Arduino stuff is a whole new hobby/industry. I'm not trying to get into all of that. I just want to see if I can make my own boost gauge (or EGT, Volt meter, etc.).

Hasenwerk-do you have any pics of the Ranger? I LOVE the ALH swap idea for that! We had a 96' that was basically trouble free for 300K miles until it gave up the ghost. They are amazing little trucks.

VincenzaV said:

Hasenwerk-do you have any picks of the Ranger? I LOVE the ALH swap idea for that! We had a 96' that was basically trouble free for 300K miles until it gave up the ghost. They are amazing little trucks.

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I have a whole write up about it in the conversion section.

Aknovaman said:

If necessary I can write step by step directions on how to set up the software to load the sketch. Just need a few days.

I just used cat-5 cable wires cause they are solid/semi-rigid and free.

Windex, Here is a link to the wiring connections.

https://youtu.be/x6wSGZ9bYPk

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That definitely means one of us will have to come up with a suitable enclosure, because too many bends and Cat5 solid copper strands will eventually snap, or get weak anyways.

turbovan+tdi said:

Thanks for sharing, this is what makes the internet great,

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No - this is what makes TDIclub great, and why I'm proud of being part of this community!

I can make it with any wire even a dead mouse cable. I just had some cat 5 laying around so I used it. All part of being a cheap SOB.

One guy was just going to use a generic pillar pod and put some tinted plastic over the hold with the OLED glued to the backside. I have some large heat shrink tubing that can go around the ARD circuit card.

Aknovaman said:

I can make it with any wire even a dead mouse cable. I just had some cat 5 laying around so I used it. All part of being a cheap SOB.

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No offense, but yeah - given the prices you quoted are for the parts coming from China directly. But I think all of us can be like that, depending on what it is. Like me - I'd love Matco tools, but I settle for Harbor Freight, because it's cheap.

One guy was just going to use a generic pillar pod and put some tinted plastic over the hold with the OLED glued to the backside. I have some large heat shrink tubing that can go around the ARD circuit card.

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I ended up ordering this stuff today on ebay. Are there better thermocouples we can get, or those with longer leads, to get through the firewall? I don't have the first idea on what's a good thermocouple or not.

For the OLED, I ordered one white and one blue/yellow. I presume either will work?

There are other options available rather than spending hundreds on a commercial EGT display. What I have shown here is a good option for some of us not having a large budget. Any of the displays will work but keep in mind if you use the 1.3 inch oled, the code needs changed to specify the correct driver chip. The color is not important but I did now ant. Yellow stripe across the top of my display. It cannot be removed, if you bought that model. I prefer the all blue version if using a clear faceplate. The white ones work well behind tinted faceplates.
eBay sells thicker thermocouples. Search for 5mm k type. I ordered several of these and will use one on my TDI.

Aknovaman said:

There are other options available rather than spending hundreds on a commercial EGT display. What I have shown here is a good option for some of us not having a large budget. Any of the displays will work but keep in mind if you use the 1.3 inch oled, the code needs changed to specify the correct driver chip. The color is not important but I did now ant. Yellow stripe across the top of my display. It cannot be removed, if you bought that model. I prefer the all blue version if using a clear faceplate. The white ones work well behind tinted faceplates.
eBay sells thicker thermocouples. Search for 5mm k type. I ordered several of these and will use one on my TDI.

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I actually couldn't find a solid blue display. I'll look again, but at least the white display will match my JSW. I could try and find blue for the 2 Mk4's.

And yes, the commercial versions are not only expensive, but when presented with the other options in the thread I'd started, I wasn't really that elated with the selection. I was thinking "Ehh, this is kinda okay, but I don't like this, or I don't like that." Your project - I love it. Mounting is another story, though. It's simple and does what it's supposed to do (and somewhat customizable).

On the thermocouples, is there a limit to how long one can go?

Great little project! For the boost gauge, think it would be possible to just listen to the signal off the stock MAP sensor so you don't have to add a secondary sensor.

Yes, you could tap into the factory map as the arduino has a very high input impedance and would nit load the signal down. I would have to test it to calibrate the display for accuracy

I have a dream of using an Arduino and controlling LED segments that sweep.... Boost on the one dial sweep, EGT on the other dial sweep. There use to be a guy called IMP Concepts that built some little unit that had a wiring nightmare, but looked awesome.

I want to find out how to trigger and build a PCB ring that can mount easy and run a small <6wire JST connector and hook everything up with small hideable wires and tuck it into the cluster for an ultra sleek look.

Keep up the good work... Ordering my parts to build one too. If nothing else, still a great project!

Using the MAX3155 form Adafruit would be advised. Yes it is more expensive, but you have built-in cold junction compensation and ferite beads on the inputs so any RF or other EMI the thermocouple wires pickup are filtered out. Sample rate for that board can comfortably be 25 ms, or in video terms 40 fps. Add a little 4-sample FIFO averaging with some bitwise operations and you still have a 10 fps, low(er) noise output faster than most meters.

Max6675 has cold junction comp already, noise is not an issue and too fast sampling leads to erratic fluctuations thats why i take 25 averages.

Sampling too fast isn't the cause of the fluctuations, it's alloying you to see the noise picked up on the lines of the thermocouple, which act like an antennae. Using a low pass filter, the ferite beads, will net more stable and accurate results than FIFO averaging or grouped averaging.

Digital, that's not what I see in my testing at ambient temps and in my cal lab injecting a simulated temperature. The chip is just not that stable and readings vary by 0.25 degrees. Likely from the measurements taken in the conversion process within the max6675. Plus between each exhaust pulse, the probe would naturally heat and cool. The reason I take rolling averages is because under diesel running engine conditions, there are reading fluctuations. Whatever the cause is, I prefer to average them and update the display at 4x per second.

900 RPM for a 4 stroke is 7.5 combustion events per second. A welded bead thermocouple has a time constant of 0.1 to 0.25 seconds. After 5 time constants, 0.5 to 1.25 seconds, has the thermocouple reached the new temperature. A thermocouple with a 1/32" sized tip has about a 1 second TC, and the more common "fast" 1/16" tips are about 3 second TCs.

I looked at the MAX6675 datasheet it has a +/- 5 to a +/- 19 LSB error which is a +/- 1.25 to +/- 4.75 °C depending on range and supply voltage. It's upper limit is 1024 °C and I can even hit 1050 °C in my modified TDI. For the details alone, the MAX31855 is still advised. Sampling error, let alone converter accuracy would put me to using that chip and it's not that much more expensive. Thermocouples are usually+/- 2-5 °C, then you have the converter error and non-linearity to deal with, if range isn't an issue.

So yeah, you're right that the noise is from the converter, but with how much there is, you'd be hard pressed to notice any other noise sources. Moreover, the thermocouple itself is a low pass filter so the individual combustion events are already averaged out due to the physics involved. I won't beat a dead horse so I'll leave it at that.

Got a source for a 3155 arduino library? I am interested In doing some testing of it in the lab for other projects.

Project goal has been to make a cheap EGT. I think I have achieved that and a real world deviation of 5 degrees is not going to ruin any engine in my world. More accurate reading are always better for me too. Thx for the input.

If you have the Arduino platform installed, you can download a library produced from Adafruit and/or Sparkfun with examples.

Long live Google and GitHub:
https://github.com/adafruit/Adafruit-MAX31855-library

Nice ! Thx much.

Has anyone come up with an idea for an enclosure yet? I'm still waiting on my arduino boards to arrive, but have the other components.

This is probably a dumb question, but where exactly would I attach the thermocouple on the car?

I have mine right where the streams converge just before getting to the turbo:

Received all my parts today from HK Now I just need the weekend to come so I'll have some time to play with this stuff.