SimBa

EDIT : I originally set this up to use one of the spare inputs for the AC switch. I later realized that this was wasteful, as the spare inputs are analog, but the AC switch is digital (on/off). I have now gone back and rewired the AC switch to use the KNOCK input on the speeduino, which goes to a digital pin. I have briefly tested this, but it is working and frees up an analog input (ironically, I'm using mine for a knock sensor because the dedicated knock input is digital).

Just in time for summer to be over, I figured out how to get AC Idle Up working on my Speeduino. I figured I’d share what I did, as it’s one of the biggest shortcomings of the SpeedyEFI PNPs in my opinion. Big shout out to Seth Mains on the SpeedyEFI troubleshooting page, as he helped answer a lot of my questions.

I’m running a 1999-2000 PNP from SpeedyEFI. Specifically the WhiteFang variant. I don’t believe there would be any issue doing this on a SeaFox or another variant.

A few notes:

• SpeedyEFI apparently added the AC signals to the latest revisions of their boards. If you bought a board around July 2023 or later you may already have the signal.
• Something similar to this method have been used by many people on the SpeedyEFI troubleshooting Facebook page (great source of SpeedyEFI specific info). I have only had it connected this way for a few days and haven’t used it extensively. In my testing it has worked well, although I need to get my settings dialed in for it to be a seamless operation.
• The signal going into the board is 12 V. There is some circuitry on the Spare Analog Input 1 & 2 paths, which hopefully protect the board, but I did not scrutinize them. Seth demonstrated that the signal coming into the board is extremely low amperage. I’m not responsible if you do this and your board breaks.
• AC Controls are only available in the latest Speeduino firmware at this point (the July 2023 FW). If you want to run the latest stable software, I believe you can get something working with programmable outputs or some modifications to the FW code.
• For terminology's sake the Adapter board is the small box (roughly 6x1x2 inches) where the Denso 76 connectors attach. Speeduino is the open source Arduino based ECU project. SpeedyEFI is a vendor who makes Speeduino based plug and plays.

The idea here is to break the pass-through signal on the AC Pressure Switch and AC Relay. On the PNP’s the signal is piped through, so that path needs to be broken and instead routed through, and controlled by, the ECU.

To do this, there are some modifications to the adapter board that need to be made. If you are on an earlier different PNP, you will not have the adapter board. The same method should work, but you will need to figure out what pins your board needs.

Highlighted here are the 2 signals that will serve as our input and output. The Refrigerant Pressure Switch will be routed to Spare Analog 1 and the AC Relay will be routed to Low Current Output 1. I have attempted to keep the coloring the same for all of the diagrams as far as the IO goes.

Going back to the adapter board, the following paths need to be joined. Solder some wire between them and add a bit of hot glue to keep the wires secure.


Flip the board over and look near the Alternator Control module. There is a trace that needs to be cut (NOT THE PINS ON THE DENSO CONNECTOR). If you don’t cut this trace then there will be continuity between all 4 I/Os involved. This is the path that would pass the AC request signal out to the AC Relay, but now we want that signal to go through the board.


I was able to cut the trace using a razor blade. Once the trace is cut you should use a multimeter to confirm that there is no continuity between the two pins.

Install the ECU into the car and grab your laptop.

The latest firmware for Speeduino has an Air Conditioning Control menu in the Accessories Menu. If you used the same pins that I did, you want to use pin A8 as the AC Request Pin and pin 26 as the AC Compressor Output Pin.
Make sure you select pin A8 and not pin 8. Pin 8 is an injector signal and will cause your AC to do some wacky things (ask me how I know).


The settings I used to test this are below. They are not perfect, but they allowed me to idle with AC on for the first time since I installed the SpeedyEFI in my car around 6 months ago.




Overall it's a pretty simple modification but should have a dramatic effect on the drivability of the car. Feel free to critique, just trying to help the community.

__SimBa__

Alejo_NIN

iTrader: (2)

did this mod and it worked like a charm!!!!


i did find that for some reason SpeedyEFI was using the same aux pin for the Check engine light but I wanted to match yours, so I guess I can always setup that for something else.

SimBa

Odd. Maybe you have a newer board than me. I actually wired in my CEL so I could use it for temp warnings. I don't believe mine was wired on the board stock.

SimBa

I realized today that both of the spare inputs are analog pins on the Arduino. I believe the KNOCK pin is unused and would likely be a more appropriate path for the ac switch signal (digital), which would save an analog input for things like oil pressure or a knock sensor signal. I will likely be going back to move the AC Switch signal to the KNOCK pin.

I do not know that that setup works, but I would expect it to unless the AC switch voltage is too low to trigger the digital on/off of the arduino.

nolig2278

what app has all those options or do i see less options cause i have a microsquirt?

SimBa

This is for Speeduino, so the firmware supports different features. This means we will have different options/menus in tunerstudio for better or worse.

SimBa

I have updated the original post with a disclaimer, but I have tested sending the AC switch signal to a digital input on the Speeduino and it is working identically to the analog input. I used the KNOCK pin on the ECU because my knock sensor has a 0-5V analog output. I am now using the A8 pin for the knock sensor signal and the Knock pin for the AC switch signal.