Ok, so when i was replacing my water pump this week the wire to the thermoswitch from the connector snapped at the base of the connector. Since I have already converted to an e fan, do i need to replace this part? Does the ECU need this sensor to run properly?

 

so maybe i should specify.... my e-fan runs continuously. Logic tells me no then, the thermoswitch off the water pump doesn't matter. (I'm assuming this thermoswitch runs the old clutch fan.) Just looking for some feedback

 

Your e-fan shouldn't run continuously. That needs to be fixed.

 

Spock disapproves of your "logic".

Take a look at the stock thermoclutch fan and try to see any electrical connections that the thermoswitch might activate.

Right...there are none- the stock fan is heat activated and mechanically controlled.

I believe the sensor who's wire you broke feeds info to the ECU.

 

You need to clarify what you have on your car, coz your posts are confusing...

Do you still have the stock thermoclutch fan?
Or have you replaced it with a electric fan?
Do you have the stock auxiliary e-fan in front of the radiator?
Which of these fans is running continuously?

The S5 has both the ECU thermosensor and the thermoswitch for the auxiliary e-fan on the back of the water pump. If you don't have the e-fan, you won't have the thermoswitch. If you only have one of those, then you've broken the ECU thermosensor and must replace it.

 

If you have and auxillary electric fan located in FRONT of the radiator, then it will run continuously if the Water Temp Switch on the water filler neck/thermostat housing has it's electrical wire (green/black) pulled off the temp switch.

If you look at the wiring diagram for the aux fan it will make complete sense to you. I believe another way to make that fan come on is to pull the BTN fuse. Might be another fuse but for right now I believe that is the fuse.

If your talking about any other fan/switch other than the one on the water thermostat housing (on top), then ignore this post.

Oh. IF it is that water temp switch with the green/black wire, that is it's only function. To operate the aux fan when the water temp is a bit over 200 degrees F. With that wire off, it'll run any time the key is put to ON.

 

That only applies to S4's, not S5's.

 

to further clarify, I'm running:

an electrical fan (don't know which manufacturer, but not stock)
that is drawing power from the fuse box, in fact the fan fuse.

NO clutch operated fan (stock, assembly removed)

the thermoswitch connector next to the thermosensor connector on the top of the waterpump busted. So on my s5, it should just run when the car is "on" and not have problems until i can get it replaced?

 

oh, my bad.

TXFCTURBOII...........Try to forget what I wrote. I was thinking stock electric auxillary fan on a series four car.

I know zippity do dah about series five/aftermarket electric fans.

 

That's BAD! The e-fan should not be connected to any part of the stock electrical system. It should be fed directly from the battery via a separate fuse and a relay, with the relay switched by an aftermarket thermoswitch.

The stock e-fan thermoswitch should be controlling the stock e-fan in front of the radiator. I don't know if whoever wired up your fan used that switch, but it shouldn't be used for an aftermarket fan being used as the main fan as it triggers the fan too late.

It sounds like your fan needs a complete rewire...

http://aaroncake.net/RX-7/efaninstall.htm

 

That switch triggers at something like 209 degrees F.

That said, here's a little story. For one reason or the other I was idling the engine with the mechanical fan off the car. Not a good practice, but anyway, after a while that aux fan came on when the water got plenty hot. Ooops. Well the fan went off a few minutes later. Hmmmm.

Then it came on a bit later......then went off. So that little sucker will do a fairly good job of cooling, at idle anyway. We're talking about it being in front of the a/c condenser also, which is in front of the radiator.

That's my story and I'm sticking with it. Don't read anything into these words. There is no secret meaning. Just a simple story.

 

The fan works just fine; I've got a warning light tied in series with the power to the fan..... if it goes out, then my fan isn't working and i stop driving. I have no auxillary e fan, only the aftermarket one; and a griffin radiator. If there is no auxillary e-fan for aux. e-fan thermoswitch to control......... then like my origi-question asked....... is it necessary to have the thermoswitch on there? Will the ECU freak out and limp me out? But i guess there is only one way to see.....

 

Maybe it does, but your description of how it's wired sounds like a failure or fire waiting to happen. I'd highly recommend you redo it properly, but it's up to you...

No.

No, the ECU has nothing to do with fan control.

Limp me out?

 

thanks for the help; and i will look into getting that fan re-wired. Oh and btw, limp me out..... limp mode.

 

I know, it just sounded funny.

 

AHHH!!!! looks like I'll be replacing that sensor anyway, now I'm having hot start issues!!!! Anyone know a good trick to bypass the sensor on an s5? Hailers?

 

AHHH AGAIN!!!!! Now my entire idiot box just lit up, and the idle bounces!

 

There are two temp switches. One is on top facing down into the filler neck on the water pump. That is for the optional fan in front of the radiator. The other sensor is the "thermosensor" which is on the backside of the waterpump and has a green plug on it. That is important so the ECU knows what temp the motor is at and it adjusts fuel accordingly. It will default to 76C I think if broken. This is so it knows how much fuel to use on cold starts. It will not operate too nice in cooler areas without it.

 

FYI, the stock fan works off of the main crank. When the air heats up it causes the clutch to "lock" and cause the fan to start turning faster. No electronics involved.

 

So the thermosensor must have busted too then, maybe just vibrated loose, the snap that locks it into place on the back of the pump busted when my dad helped me remove the housing. The lights on are either from a bad alternator, fried CPU or loose wires to the CPU, right?

 

I thought you said you broke the fan thermoswitch, not the ECU thermosensor. The fan switch has no effect on the engine's operation. Which one is it?

Or you haven't plugged the alternator's 2-pin connector back in.

The S5's temp switch is on the back of the water pump next to the thermosensor, like I said above. Don't confuse him with wrong info...

 

Sorry, I'm not trying to confuse anyone, I did completely break off the thermoSWITCH connector, I also cracked the snap on the thermoSENSOR connector. But it seems those connections were just loose (the thermoSENSOR and the 2-pin alternator connector), I took them out and very snugly put them back in and I haven't had any hot start problems today, and my light box is back to normal.... I tested the alternator and it's working fine as well. So problem solved for now?

New question: currently I've got stock primary injectors and 720cc secondaries w/ a walbro fuel pump and a Apexi S-AFC II. Would it be within the limits to move the 720cc's to the primary injectors and upgrade the secondaries to 1000cc's?