yes this is jj

Hey guys.
I'm having issues with my cooling fan activation.

Here's the story:

1995 Mazda Miata 1.8 Manual Transmission with MSPNP
Running MegaTune 2.25 P1 with Firmware ver. MSExtra hr_10g****************

I had installed a set of individual throttle bodies back in February.
I know you guys aren't too fond of these, and now I'm not either...but help me out here if you can.
I tuned them up until about two weeks ago when I decided to put the stock intake manifold back in.
The cooling fan was working perfectly fine with the ITB's installed.
I removed the ITB's, changed the injectors back to stock (From Denso 310 cc's) , reversed the TPS wires ( They needed to be reversed to work with the Toyota TPS required to run the ITB's) , Ran new fuel hose, Reinstalled the stock manifold.
Nothing was touched near the cooling fan.

I started the car and allowed the coolant temp to climb, after getting it to idle around 14.7 - 15.3 AFR at around 1000 RPM.
I'm aware there is a temperature differential in the "More Settings > Outputs" menu for the coolant temperature, requiring you to enter a value 40 F higher than the temperature you want the fans to activate at.
Thus, the value in the box was set at 240 F, and the fans would normally activate at 200 F.

However, this time, the fan never activated, and the coolant temp rose to 215 F and didn't get any hotter.
I drove the car for a couple days, and the fan still didnt activate at any point during driving.
The radiator had pressure cracks in it before this, and the radiator blew soon thereafter while I was inspecting the wiring harness with the engine running.

So!
I have done these things to try to pinpoint the cause of the fans not activating:

- Applied voltage directly to the main fan. The fan activates and thus, is in working condition.
- Probed the Cooling Fan Relay. The relay is in working condition. Continuity across terminals.

Considering there's not much else in the cooling fan circuit, I resorted to looking at MegaTune in live view.
The coolant temperature reads as normal, and climbs steadily as normal on screen in MegaTune.

Now, here's where things get hairy.
I went into "More Settings > Outputs" and lowered the activation temperature to a low figure, such as 100 F.
The fan still didn't turn on.
Next, I tried using a different source for the output, so I selected the Battery as a source, and set the activation value at 12 (for 12V).
Voila! The fan turns on, and on the bottom of the screen OUTPUT 2 is highlighted in green.
I tried going back to coolant temperature as a source, and setting it at 100 F again.
OUTPUT 2 turned off, and coolant fans turned off.
I then tried entering a much lower value, 30 F to be specific.
OUTPUT 2 turned on, and the fans turned on.
So apparently, The CLT Sensor isn't working very well as an input for the ECU to turn the fan on.

Does anyone know if this problem can be attributed to firmware, or does anyone have any other spectulations?
I'm thinking of probing the coolant temp sensor next, although it is reading normal in MegaTune, the fans just aren't activating.

Any help you could provide would be greatly appreciated!!

JJ

patsmx5

iTrader: (16)

Try power cycling the MS after switching the settings in Megatune. I.E., change settings, burn, car off, car on, start, see if it works. Thank me later.

Braineack

iTrader: (62)

just fwiw, the MS doesn't record higher than 215*F.

Joe Perez

iTrader: (8)

Have you re-flashed the MS firmware recently?

The fact that MT is reading properly and yet MS isn't doing what it should is why I ask. See, if you re-loaded firmware into the MS, yet screwed up with EasyTherm (or forgot to use it entirely) then the gauge display in MegaTune would still look normal, however internally the MS would not know what to do with the CLT reading.

Confusing? Here's why: The MS samples the CLT sensor with an 8 bit ADC. The raw value of this conversion is transmitted out to Megatune. MT reads the thermfactor.inc file on your laptop to decode the raw ADC values and display the temperature correctly. This, apparently, is working.

But it sounds like internally, the MS is missing this conversion table. That's basically what happens when you use EasyTherm- it writes a table into the firmware telling the MS what temperatures the raw ADC values correspond to.

So here's a test:

1- Disconnect coils.
2- Save out an MSQ.
3- Get your raw HR10g distribution, run it through EasyTherm, and re-flash the MS.
4- Re-load MSQ
5- Re-connect coils
6- Set your fan temp to something like 140, and see what happens.

yes this is jj

Thanks, guys.
I will definitely try this this coming week when I get some time.
Does anyone know if 10g is the current firmware, or is there an update?

Joe Perez

iTrader: (8)

HR10g is current.

You can always find the latest build of HR in this thread: http://www.msextra.com/viewtopic.php?f=90&t=25336 which is constantly updated.

yes this is jj

Thanks, guys!
I will try this this coming weekend when I install the new radiator.

yes this is jj

Hey, thanks for the help again guys.
I reflashed the ECU with hr_10g again, and reset the value for the fans to turn on, and they did.
So all is working as normal again!
Thank you very much!