wstrohm

I agree, considering your location... you have probably made the wiser choice.

Jeff20B

iTrader: (13)

Get one of those huge capacitors the car audio guys use. When the fans kick on, they draw a lot of amps (amperes, not amplifiers hah) until they spin up to normal operating speed.

DaleClark

iTrader: (55)

My 2 cents on this -

Mazda did a LOT of bandaids on the FD to deal with the high engine compartment temps. This is the way it goes -

- They have to pass cold start emissions, so they put on a precat, which is a massive furnace right off the turbos in the engine compartment.
- Trying to get better fuel economy/emissions, they run the car's water temp higher than it should be
- Cars are literally catching fire due to fuel and coolant leaks on top of the engine, they do a recall to replace those hoses with upgraded parts to take the heat
- Still too hot under the hood, they do the fan recall to help get heat out from under the hood.

So, you make the car WAY too damn hot, then you bandaid it to try and cool it down.

The RIGHT approach is to have the car not run so damn hot in the first place. If you have that, all the band-aids are not necessary.

- Get a ceramic coated downpipe, engine bay temps drop like a ROCK compared to the precat.
- Get an FC thermoswitch, change the fan on point on the PowerFC, fans are now keeping coolant temps at 80-90 deg. C where they should be, not 110 deg. C.

You've now fixed the 2 problems Mazda tried to work around.

If you've ever worked on a car with a precat that's bone stock, you'll realize how CRAZY hot it gets under the hood. I've popped the hood on a stock FD and felt a heat wave roll out like from an oven. Trying to even get near the turbo side is ridiculous, it's just INSANE hot. This is what baked all the vacuum lines and wiring harnesses, causing further problems.

My car has been running without the fan mod for 5+ years now in Florida heat. Part of that time I drove my car on service calls FOR WORK, not just to work. 80-90 degree water temps all day long, harness is still soft and nice, under the hood is all good.

There's no good reason to kill your battery with the fans running for a half hour after shutdown. Rip that **** out pronto, do it right.

Dale

RENESISFD

iTrader: (13)

^ Good info but he is still running a stock computer though.


John

adamrs80

iTrader: (7)

Thanks Dale for the input. I do have an hks dp wrapped in the "DEI" fiberglass roll, running a pettit fan switch and a koyo n-flow. I'm pretty sure my temps don't pass 95 c. on my greedy temp gauge. I feel like im on the safe side of things cooling-wise. Do I need to remove the fan mod?

wstrohm

If the Stock PCME is in the car, makes no difference what the trip point of the fan thermoswitch is, if it's below 100-104°C. That's because the stock PCME sends no power-up signal to the fans until coolant temp is in that range. A 97°C fan switch does only one thing: it causes the fans to run faster once the ECU sends that signal, which occurs at 100 - 104°C. You could put a 40°C fan switch in, and the fans would still not come on until 100 - 104°C. A PFC may change all that, but I wouldn't know.

adamrs80

iTrader: (7)

I'm certain my fans come on between 80-85 deg c. I can hear them and see my rpms drop a little as the alrernator goes under load.

wstrohm

Are you sure that is not your A/C compressor cycling on and off? What I wrote above applies only if the A/C is OFF. If A/C is ON, as you can see from the truth tables, the input to cooling fan relay no. 1 from the A/C system will activate fans at their lowest speed. But that doesn't come from the PCME (ECU), it's a separate fan signal. And I don't think it is a function of coolant temperature at all, so it could easily occur at lower temps. My point was that even if both cooling fans have their second set of ground returns active (fan thermoswitch is closed), the higher fan speed cannot activate until the PCME puts +12 volts on the topsides of the #2 and #4 relay coils. That happens (with the stock PCME) at 100 - 104°C.

Cgotto6

iTrader: (8)

Glad you got it figured out, but I would still clean your connections. If you are having problems starting the car over a matter of a fraction of a volt you have other issues. Cars still should crank with voltage in the 9-10 range.

I suspect you will reencounter starting issues in some time once the corrosion sets in more.

But then again this is all speculation as I cant see the car. Just glad to hear you got it goin cause thats what the forum is all about.

Oh, and you said staic voltage is not an indication of the current charge state of a battery...Care to elaborate on this? I have never seen a real world situation when the voltage read at the battery terminals has "lied" so to say....

wstrohm

See the chart below: 12.0 volts on an unloaded car battery could be indicating only a 12% charge left on it. For more information see this article (PDF format).

Cgotto6

iTrader: (8)

Thats a sweet pdf. Thanks for posting, always good to see some good info.

twinsinside

iTrader: (34)

I've got my PFC fans set to kick on at 87, and that's exactly when they kick in.

Dale speaks the truth, once I got my DP coated (did manifolds and heat shields too for giggles). The hottest I've been able to get it so far is 92. Thanks IRP!