My 92 turbo Miata has a MS3Pro Plug and Play and runs great. I am now installing a FM Stage 2 V2 airflow kit, which includes a fan that can be controlled by the ECU through a PWM signal. Though FM does not provide instructions for MS3Pro this looks like an easy conversion but I want to confirm my thinking before testing and hope that someone on the forum has already done this. Can someone help?

The MS3Pro Plug and Play hooks directly into the OEM harness. The fan control is run through Output Channel PWM2 on the MS3Pro. This output can be reset from Open/Close to PWM and a map created.
- See attached schematic. The cooling fan relay will not be used. By wiring the BLK/GRN cable that now controls the cooling fan relay to the PWM input in the SPAL harness, and reprogramming the output to a PWM the fan speed should be controlled by the MS3Pro table I create. Right?
- I would like to run the fan at 60% whenever AC is on but cannot see a way to program the MS3Pro separately for AC. Am I missing something? If the MS3Pro cannot have a separate map for "AC on" FM provides a simple workaround which I plan to implement, running the fan at 60% whenever AC is on.

I look forward to your wise responses.

 

I know this is many months late, but I hope this response will help with you or anyone else who runs into this.

I too wanted to get this kit and keep my AC, The kit wired in fine and I was able to get it all working. Sadly there are no options in tuner studio to let you change the PDM table based on AC as well as temperature. Currently what i do is have two separate PDM outputs that are set to output to the same pin. On days that I know I will be running the AC I connect on my phone and turn the AC output on, and the regular output off or vise versa. I had planned to wire in a relay that would trigger when the compressor clutch goes on that would change the wire going to the pwm controller. Supposedly this feature will be added to tuner studio, but looking at the age of the threads on the mega squirt development forum it does not look too likely.

Does anyone know if i will be able to reuse the stock AC fan relay for in input switching plan? or will I need to get a new one?

 

That is sad news. I was on the fence about buying this kit. They suggested a potentiometer in the way. It might be half assed but you probably wouldn't stress the alternator if the fan is at like 30% all the time? This might be enough for day to day use if the kit is as efficient as they claim.
And on track you'd switch to pwm?

 

I may be wrong but I am pretty sure you need a PWM signal to even get the fans to run.

I got their coolant reroute, crossflow radiator, and new stage two fan kit and now I have no overheating issues even with AC on. Overall its a pretty good kit. my only gripe is the issue with AC. I think that a single pin double throw relay would solve the issue. (see attached)

This thread appears to claim there might be some way to do it in within megasquirt but I cant make sense of it.:
https://www.msextra.com/forums/viewt...?f=125&t=59368

I am going to try and play around with tuner studio settings to get it to work and if not I will wire in the relay. I am getting tired of changing it on my phone every time i want to turn on the AC.

 

While I don't use the FM fan itself, I do use a C5 corvette PWM fan controller. What I do is I wired a direct output from the Megasquirt PWM3 direct to the input on my PWM controller and I created a table in tuner studio that increases PWM duty cycle as CLT increases. No worries about AC kicking on the fan the fan slowly ramps itself up based on CLT and with ac use within a mater of seconds the fan will follow anyway.

 

I solved my fan control exactly as shown on Wulfspade's diagram with a relay switching between the two PWM outputs depending on whether the A/C is on or off, and it works great. Two different PWM tables, and the fan runs on one with the A/C off and the second with the A/C on.

 

I know I'm late to the party but what was your outcome to getting this to work with the MS? Were you successful? Did you wire it up per your schematic? I have the FM Stage 3 cooling and want to keep my AC also. Thanks in advance.

 

Yes, I did get it to work following a diagram approximately per above with one PWM output for AC on (min. 60% fan speed) and one for AC off. I am not next to my car and I can't remember the detail of the logic, but I had to disconnect the temp sensing by pulling the connector with the blue wire on the front of the engine (see picture below) to make the fan work correctly

.

 

Question for you. Did your setup since it was MegaSquirt PMP were the fans plugged into the factory harness or did you have to run wires to the ECU?

 

I ran separate power. I will see the car this weekend and can take some pictures.

 

I hadn't had the chance to chance wire up the relay yet, but I'm pretty confident it will work.

I saw a lot of people requesting it on the MS extra forums and was hoping that it was going to be updated in the next set of firmware. I would advise you to go there and post. I tried calling Megasquirt about this and they told me to post there saying "the squeaky wheel gets the grease"

 

Thanks, I will be waiting.

 

Can you send me the link for the MS extra forums? I haven't spent much time there and want to post to the correct spot. Thanks in advance

 

I would like to make sure I'm reading this correctly. You are using the existing OEM harness to control the fans of your Stage 2 system. Correct? What mhz did you use? Thanks, Max

 

Also, where did you create the map? Was it under advance engine? Sorry for the basic questions. I'm new to programming a MS and I'm just trying to get this setup and will take it to the tuner when I get it running.
Thanks,
Max

 

You should wire in a dedicated power and ground, don't use the factory harness, it isn't designed for the higher amp load. The FM stage 2 kit uses 100 Hz.

 

Advanced Engine -> Generic PWM output A. Choose coolant as your load axis, and curve as opposed to table. Copy the values from FM's instructions. If you have the values in correctly, you should have like an RPMdot floating in the field that matches your current coolant temp.

For the output pin, I choose Injector I, which normally goes to the A/C fan relay. I cut that wire under the hood and connected it to the PWM input on the fan kit. Follow the instructions above if you want to run two PWM maps depending on A/C status.

 

PWM fan control will be added to firmware 1.5.3

 

Do you have any idea as to when they are going to be releasing the 1.5.3 beta? I have been lurking on the MSextra forums but I haven`t seen any updates.

 

I just saw it on msextra forum posted by Matt.