TB Coolant bypass mod
#16
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I'm not sure about the throttle by wire vehicles, but the other Toyotas I have worked with, the coolant controls the Idle Air Control valve in the throttle body. There is typically a valve in the throttle body that allows air to bypass the throttle plate, and as the coolant heats up as the engine comes to temp, it closes the valve to lower the idle speed. The only thing negative I can think of is maybe the car won't idle down properly once warmed up. The ISF may not even have this.
#17
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More so than the TB just freezing shut, I imagine there are conditions whereby condensation can form inside the TB and then freeze into ice. Lexus sells these cars all over the world so the TB coolant loop is necessary to prevent that, especially in very cold climates.
Easy way to test improvement from the bypass mod is to log IATs before and after. Given same/similar atmospheric conditions and driving, one should show IATs trending lower.
Easy way to test improvement from the bypass mod is to log IATs before and after. Given same/similar atmospheric conditions and driving, one should show IATs trending lower.
#18
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Your welcome. To make it look clean I pulled the TB off and pulled the two tube pieces out of the TB and then capped the two coolant passages on the motor with the samco caps. I have seen people use rubber caps and those tend to rip and leak so I found samco made caps specifically for blocking off coolant passages. Plus they have a lifetime warranty.
#20
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when the engine is hot, and warming when cold. I would think the engine area near the TB could far exceed 200* during summer driving and the
coolant line may actually help reduce the TB temps.
#21
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You guys want a quick thrill, unplug the connector on the solenoid for the intake air box / secondary air flap.
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Joe Z
#23
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This guy did a before and after with his WS6. His math is off though he said after both 24 mile drives his temperature difference was 16.65 degrees lower after the coolant bypass, however 96.0 minus 73.35 is 22.65 not 16.65.
#24
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Interesting video.....Thanks for the upload!
#25
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The throttle body won't ice up in a cold climate ever. The humidity is near zero when it's cold outside. Freezing is more likely in humid environments at low throttle openings because the air is highly endothermic at low throttle openings (gas going from high pressure to low pressure, same concept as most refrigeration).
Does this actually happen? Apparently it is enough of a concern the engineers made sure they spent the money on it. There is nothing a car company does that costs money for no reason at all.
All that said, this has been a common modification over the years without measurable results in any direction other than the obvious loss of full coolant temperature in the throttle body. Supra guys made all kinds of wild claims about it that no one could ever prove.
Does this actually happen? Apparently it is enough of a concern the engineers made sure they spent the money on it. There is nothing a car company does that costs money for no reason at all.
All that said, this has been a common modification over the years without measurable results in any direction other than the obvious loss of full coolant temperature in the throttle body. Supra guys made all kinds of wild claims about it that no one could ever prove.
#27
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That I can not remember BUT if you find out the size of the hose on the throttle body your set. I measured the inside of the hose when I pulled them off and then ordered the caps. If you find the outside diameter of the hose you can go to autozone and measure the inside of a hose with the same outside diameter.
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