How is the intercooler water pump speed triggered?

[ciper]

I would guess that the ECU has a trigger similar to how it shuts the AC compressor off to control intercooler pump speed if its based on load.

Or is the pump speed dependant on temperature? Which temperature if so, intake air or fluid leaving the intercooler?

[zak]

If you are talking about the stock AWI on the legacy RSs, they had a boost activated pump. Low boost was one speed for a certain amount of time, and high boost led to a faster pump speed for some amount of time.
At least I think thats it........

[vrg3]

This page from the RS factory service manual seems to indicate it's primarily based on TPS inputs, much like the A/C cut:

http://www.legacycentral.org/library/rod/ic/3.htm

[zak]

ah, good find
I think that I was thinking of the typhoon truck thing. The conversation I thought I had with this guy was actually about his typhoon, and not a legacy RS
My inner mind must have spurted that out, maybe because it was the only other older AWI turbo vehicle?
I think my finals made me insane.....oh well.......

[Legacy777]

The A/C cut is based mostly on TPS position. However the computer uses that input to calc a load value....so I guess it's close to being one in the same.

I would think you could rig something similar up with the intercooler pump....or maybe make a boost sensitive switch.

[vrg3]

I think ideally it would be a combination of TPS input and temperature... You definitely want to run at full speed if the temperature is high, but that's kind of backwards. Ideally you'd want to run at full speed if the temperature is about to spike, which is often indicated by the throttle opening quickly or widely.

Controlling by boost would be easier than by temperature since you already have a pressure sensor. But again you'd want to activate just before boost builds.

That's just my take on it... it's similar to how you'd ideally want to activate water spray on air/air intercoolers.

[ciper]

Can you guys help me to find or create a low cost curcuit for a temperature triggered relay?

My idea would be a curcuit that waits for a certain resistance value and anything past that triggers the relay. I could then use a water temperature sensor accurate for temps between 70-90 degree.

I could have the pump run at low speed (drop the volage) while the engine is runinng then have this temperature control curcuit switch to higher speed.

I think I would monitor the temperature just as it leaves the intercooler since this will be the warmest spot in the system. That way it doesnt use all the "storage" of the water resovoir before activating.

[rsstiboy]

I bypassed my speed controller, so it runs on the full speed setting all the time, I will see if I can find some photos of how to do it....

[vrg3]

ciper - Set up a voltage divider where one of the resistors is the thermistor you're using to measure temperature (a GM coolant/air temperature sensor is probably the way to go). Have the output go to a comparator whose other input is the output of a potentiometer set up as another voltage divider. Have its output control a relay (through a transistor, if necessary).

Just realize that this will be reactive and not proactive.

[ciper]

rsstiboy: Thanks for the help, but my car didnt have a intercooler to begin with. Im building it myself. The pump I will end up using will most likely be a magnetic drive, so no chance of anything every leaking!

vrg3: Alhthough I can understand how a circuit functions once its built I would need specific names for the parts you mention, I guess I could google for a voltage divider but if you could help me to find it that would be great.


edit: Lets continue the discussion regarding the switch here http://bbs.legacycentral.org/viewtopic.php?t=14630