Im installing a New Koyo Radiator which does not have the hole at the bottom left corner for the Water Temp Switch. I was planning on jumping the wires, but how will this affect my warm and cold start ups? (stock 88 TII)

 

anyone? what temp does it send to the ecu when jumpered!

 

Is this the switch for the A/C fan-turns on when the cold side of the radiator hits 207*?

 

The A/C fan switch is on the top of the water pump housing.

The switch you're talking about is used by the ECU to determine whether or not the accelerated warm up system should be used (BAC + AWS). When the water temp is cold, the switch is open, and you get the engine reving to 3k at startup. But once the temp starts to increase, the switch closes and stays closed, so the accelerated warm up feature will not be used if the engine is stopped and started again. The switching temperature is low; I can't remember what it was exactly, but it's something like 80-100 F.

 

so could i just buy a flip switch and do it manually from inside the car untill i track down an s4 koyo rad? (ill have a aftermarket temp gauge soon)

 

its not a temp gauge, if the engine is HOT it wont do that 3k rpm and then 1,500 rpm accelerated idle on start

That function is only for cold-starts, thus the sensor.

I'm not sure what you should do with it, I think if you disconnect it the lack of input to the ecu will make it bypass the accel idle, but it may put your check engine light on

try it out

 

So...help me understand. Why does my S5 vert have an active operational accelerated warmup system, yet does not have the sender in the bottom of the radiator? Many S4 and S5 cars do not have that sender.

I thought the water thermosensor is on the back of water pump housing.

Can you explain this to me? Just trying to understand.

Thanks!

 

^^I think you were right what it is, whenever its super hot my a/c fan kicks on even when the cars off/key out if I can recall (well the engine wasnt on nor was ac)

Its a S5, i dont recall seeing a sensor down there but i didnt take the undertray off, nor have i seen a sensor around the water pump :S

 

S4s don't have a check engine light to annoy us, so disconnecting it won't do much.

I wouldn't worry about it. The accelerated warm up system is not necessary.

 

It's bad for the engine I'd think, my car doesnt really like revving up to 3k rpm it'll sometimes spit out abunch of smoke, if i kick it down and let it warm up at 1.5k its ok.

I wish I could disable it, I don't leave the house past 9pm so the neighbors arnt bothered by the high revs, even 1,5k is too much

 

In the S5 FSM, section 4A Pg. F1-40 shows the water thermosensor (green plug on water pump housing) as an input for the accelerated warmup system. So it is responsible for the switching of the system rather than the thermoswitch found on S4 radiators.

The S4 has the same water thermosensor on the water pump housing, but it doesn't look like it has any effect on the AWS like the S5 one. In both S4 & S5, the thermosensor is used by the ECU for air/fuel corrections, etc.. as well. Also, I found the exact temp the thermoswitch triggers at in the S4 FSM. Section 4A, pg. 46 shows it as 59-66.2 F, so it's even lower than I was estimating before.

 

S4's have the sensor at the bottom of the radiator, S5's do not (I should have been clear at the beginning i have an S4)

The sensor at the top of the coolant neck controls the fan.
(The Water Thermo Sensor) the sensor behind the water pump checks the Engines coolant temperature.
(The Water Temperature Switch) the sensor at the bottom of the radiator checks the radiator's coolant temperature.

Both of the water sensors on the s4 engine report to the ecu and effect the cold start assist.

 

its not bad for the engine. As for the smoke coming from yours have fun with your rebuild .

 

don't worry about it

 

It's done that since I was a little child, and the cars the same age as me

Actually it really is close to my bday, I think the manu date was june or july (Im june), it was bought in dec of the same year i was born.

 

looks like your just burning more oil than normal, i was just messing around before

thanks for the info rotary rocket, i know im a pain in the *** and i should leave it alone, but its always a pain to get it running in the cold and i did spend money switching everything over from jdm to usdm so i could have the accelerated warm up system.
i have an extra switch so ill just set it up and flip the switch close when the car reaches 60F

 

I'm the opposite. My engine is mostly J-spec & my Rtek disables the accelerated warm up anyhow. I've never needed it to start the car on cold mornings, and don't want it back.

And the switch you're talking about will need to be 'OFF' by default (open circuit) and then 'ON' when you flip it (closed circuit). You would then leave it in the 'ON' position while driving around.

 

thanks man