Arduino Automatic Coolant Temp Hack for Better MPG's

Cant wait to hear your results.

 

Today I had some trouble with it faking the temperature. As I was headed home the engine warmed up to about 110F and the Arduino started faking the temp. Some time later I noticed that the LED was red but the temperature on the scangauge was about 143F. For some reason it thought the real temperature was too hot. I tried resetting several times on the road but it just went back to the red LED indicating it was too hot even though the real temp was well below stop temp setting. When I got home it stopped doing this so I could not hook up my PC to capture the serial output of the Arduino.

I will continue to monitor this before I put this in a project box.

 

I think I may have fixed my problem. After looking at the serial out the average was just not right for the input. After fiddling around with the wires I found that one of my wire taps was the issue or so I think. When I wiggled it the average wondered around a LOT. So instead of using my crappy wire taps I just twisted the wires together and wrapped them in black tape. I tested it again and this time the numbers were as rock solid as before.

I think the heat may have expanded the plastic and metal in the wire tap just a bit to cause this issue. I will find out if my problem is gone tomorrow after I get off work.

 

No problems today.

I should have this in a project box by the weekend. I tried to make a shield last week but it was a complete failure. I used a radio shack double sided perfboard and when I checked all my connections with a multimeter it looked fine. Nothing was shorted. When I hooked it up to the car there was a small spark near the digital pot and some magic smoke appeared. Aparently there was either a defect in the board or there was a whisker that just did not show up on my multimeter when I did my checks. I think I only damaged the digital pot. The Arduino seemed fine when I ran some tests with it.

This time instead of making a shield I have compacted everything as best I can onto a generic single sided perfboard. I'm just going to use some wires to go to the perfboard to the Arduino. You'll see when I get it finished. It currently looks pretty good in the CAD software and has a very small footprint. I think if you combine this with a Arduino nano or mini you could stuff it in a very small box or just wrap it up in some electrical tape. I managed to put the LED on but if you left it off you could make it even smaller.

I might get started on the perfboard tonight if I get time.

 

Just wanted to give an update.

I still have my breadboard in the car. I'm having trouble getting the perfboard version to work. Kind of looks like a short somewhere but I cant find it with my multimeter.

I'm still waiting for warm weather to see how it performs in the heat.

seilerts how is yours coming along?

 

Sorry I'm not putting a kit together. You'll have to source out your own parts.

Just to give an update.

Finally had a really hot day today. The temp in the car was well over 100F when I left from work. The circuit failed to fake the temperature so There still must be some component that is affected by the heat. I'll bring my mini laptop with me tomorrow to see if I can tell whats going on. Thats if its hot again.

I'm going to get one of ccdisce ECT spoofers since he is offering it cheap but I still want to get this Arduino version working just so there is another option out there for those of us that want to play around a bit. I will continue to work on the Arduino version but its not really a high priority at the moment.


Thanks ItsNotAboutTheMoney. I make mistakes like that all the time. I'll try it out again when I get time.

 

I took a look at the serial output today and I'm just wondering if the Arduino's ADC reference voltage is being affected by the ambient temperature? Its acting like what its seeing is a different voltage than what it actually is. So it thinks its seeing the correct numbers when actually its not if that makes sense.

I will try to bring some canned air with me next time to see if cooling down the Arduino changes anything. If not I will move on to the transistor then the digital pot.

 

Bob Wilson did it on the gen 1. NHW11 Prius Temperature Hack

 

No. I'm no longer using the Arduino. I'm using ccdisce's version which I think he is still selling.

http://priuschat.com/forums/gen-ii-...-ect-spoofer-automatic-coolant-temp-hack.html


The device does help on a stock Prius but you have to know how to use it along with pulse and glide. It helps a lot if you have a plug in conversion like I do.