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Discussion Starter #1
Many car cut out a/c compressor when wide open throttle to give maximum acceleration. First gen Honda Insight is not one of those cars.

I'm in the testing phrase of my Arduino Uno with a relay shield a/c compressor cut out project.

Code is pretty simple: When Arduino detected the TPS is over 50%, it will cut out a/c immediately. When TPS drops below 50%, Arduino will wait 4 seconds before allowing a/c to re-engage.

I hope to get this finalized before the start of 110F AZ summer!
 

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That's pretty cool! There's an incentive to learn to program the Arduino.

Sam
 

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Code is pretty simple: When Arduino detected the TPS is over 50%, it will cut out a/c immediately. When TPS drops below 50%, Arduino will wait 4 seconds before allowing a/c to re-engage.
How hard would it be, would it be possible, to use/program a different formula - such as calculating a moving average of TPS slope and using that as the AC disable threshold? Seems like you could use something like that to signal any time you're trying to accelerate 'hard enough' that you'd want the AC to disable... The steepness of the TPS slope (i.e. the more throttle position changes positively), determines when the AC is disabled. You'd have to figure out what slope would qualify. Not very steep slopes would correspond to only modest pedal pressing and probably wouldn't warrant AC disable; probably something more than 25% slope would disable AC...

Oh, also, I think 'TPV', throttle position voltage, has a finer resolution than TPS...
 

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What's wrong with using your finger to disable the AC?
Simple ON or OFF.
 

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What's wrong with using your finger to disable the AC?
Simple ON or OFF.
When you punch it in the emergency situation, you may not be able to reach out and touch that button
 

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When you punch it in the emergency situation, you may not be able to reach out and touch that button
Maybe, maybe not, but it sure wouldn't be because of the brutal acceleration... :)
 

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Maybe, maybe not, but it sure wouldn't be because of the brutal acceleration... :)
Lol that's the truth.

I've wished for something similar to this for a while. Maybe write it up when you're done so others can reproduce it.
 

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Why can't you just use an adjustable vacuum switch hooked to AC power line. Adjust it to whatever your driving style dictates.
 

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Why can't you just use an adjustable vacuum switch hooked to AC power line. Adjust it to whatever your driving style dictates.
Not as flexible as arduino

could we also block IMA charging of any kind durring acceleration?

most modern cars shut down the alternator during acceleration
 

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^ I know it does it sometimes, I don't think it does it all the time... Can't say how much it's one or the other though. I'm thinking it does it most of the time, and when it doesn't, that's more of a fluke. But I'm not totally sure...

Oh, also fyi, most IMA charging (background charging) is disabled when you accelerate (or simply at higher throttle positions, higher loads), but 'forced charging' - the charge you get after a neg recal - isn't disabled, not until the pack gets charged some amount...
 

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Discussion Starter #13 (Edited)
How hard would it be, would it be possible, to use/program a different formula - such as calculating a moving average of TPS slope and using that as the AC disable threshold? Seems like you could use something like that to signal any time you're trying to accelerate 'hard enough' that you'd want the AC to disable... The steepness of the TPS slope (i.e. the more throttle position changes positively), determines when the AC is disabled. You'd have to figure out what slope would qualify. Not very steep slopes would correspond to only modest pedal pressing and probably wouldn't warrant AC disable; probably something more than 25% slope would disable AC...
Can I do it? Sure. But I've been monitoring my TPS and honestly don't see the need to calculate the TPS slope.


I know when primary 02 is below .42v and second o2 is at 0v, that's when leanburn is activated.
I know lean burn activates when TPS is between 14-18%, and leanburn will remain active between 12-29% if throttle input is slow.
I know my usually acceleration from a dead stop is between 30-40%
I know 10% is no throttle input and 90% is max throttle.

 

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Try that speed in three different gears, 3, 4, 5 and see what the difference is.
IT might be interesting. (Especially the LOAD reading)
 

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I bought a Jaycar kit that does the A/C cut off during modest (or heavy) acceleration and it's adjustable. The kit comes with the board and all the electronic components. I think the box/housing was additional. I just checked the price plus shipping of the kit and it would be $33 to GA. I can give a recommendation for their housing as well, an additional $3 or so.

Mine's been working perfectly for 3 years now. I love it!

Here's the thread where it was discussed if anyone's interested:

https://www.insightcentral.net/forums/modifications-technical-issues/89977-air-conditioner-controller-kicks-off-c-throttle-position.html
 

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Discussion Starter #16 (Edited)
Try that speed in three different gears, 3, 4, 5 and see what the difference is.
IT might be interesting. (Especially the LOAD reading)
Third


Forth


Fifth



Looks like high load and low TPS is the ticket of activating lean burn.


What's wrong with using your finger to disable the AC?
Simple ON or OFF.
I prefer using my foot to control my rate of acceleration. Much simpler and keep my eyes on the road.



Back on topic, found the TPS and a/c relay wiring at the passenger side foot well. Should be an easy wiring job to put the Ardiuno next to the ECU.

Going to use a relay shield for this.
 

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Looks like high load and low TPS is the ticket of activating lean burn.
Great idea, looking at AF ratio plotted against other parameters. I have some data from a run a month or two ago. Here's TPS vs Air/Fuel Ratio for some data collected in February. I think.

throttle position vs AF ratio - 53xls.jpg

Note that lean burn is not present at 0 TPS or above 20. (I think this is %.)

And here is data for CLV% (I believe this is % load) vs A/F ratio:

af vs clv 53xls.jpg

The chart shows lean burn at pretty much the same loads as stoichiometric. I guess we need a good definition of "load".

Here is AF radio plotted against fuel injection duration in ms. I was kinda hypermiling, so you don't have a lot of pedal-to-the-metal data here:

af vs fuel injection duration ms - 53xls.jpg

Here are the earlier plots against RPM and speed.

lean-burn-vs-RPM-2.jpg

lean-burn-vs-speed.jpg
 

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Discussion Starter #18 (Edited)
Great idea, looking at AF ratio plotted against other parameters. I have some data from a run a month or two ago. Here's TPS vs Air/Fuel Ratio for some data collected in February. I think.

Note that lean burn is not present at 0 TPS or above 20. (I think this is %.)
This is getting off topic, and I'm not sure how you read your a/f but my car can get steady lean burn below 29% of throttle.


 

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Discussion Starter #19 (Edited)
The project is a success.

Wiring diagram is here, pages taking from "Honda-Insight-2000-2006" wiring.pdf

http://www.thelostartof.net/tryingbe/insight/wotaccutout/ac wiring.pdf
http://www.thelostartof.net/tryingbe/insight/wotaccutout/tps.pdf

TPS RED/BLK wire is on C plug at the ECU.
AC compressor RED wire at on A plug at the ECU. There are two red wires on that plug, use your multimeter to confirm before cutting the wire!

I used an Arduino clone, a relay shield, and a 3ple Decker Case for Arduino for my setup.
TPS wire is spice into and goes to the Arduino analog port
AC compressor wire is cut, then extended the wires to the relay COM1 and NC1

When Arduino detected TPS is over 50%, relay disable the AC wire connection. When TPS drops below 50%, Arduino counts to 4 seconds before re-enable A/C wire connection. Works great.

A plug

C plug

ECU and Arduino Uno at passenger footwell. I got the 12v from the cigratte lighter and ground it at the ground point behind the glove box.
 
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