Hello everyone,

Figure I share this mod with you guys since it’s fairly cheap and helps keep the TB (throttle body) cooler since the coolant won’t circulate through it anymore. I used some Samco Caps to plug both ports that use to connect to the TB. The TB has two ports underneath where the coolant would travel through which heat it up especially if you drive hard. I notice the TB being significantly cooler now that I don’t have the coolant running through the bottom of the TB. Did this mod since day 1 and have had it like this for 3 years now. I got the idea from when I had my Acura TL and was on Acurazine. Popular mod for the Acura back in the day. Video of someone testing this on a WS6 on post #23.

 

These are the two ports I’m talking about on our TB.

 

So just cap that and remove the hoses to the TB?

 

Yes. Make sure whatever you use to cap it off is strong otherwise you will have a leak. The samco caps I use are specifically for that so no worries there. I would not use a regular vacuum cap for that.

 

Thanks for this.

Why does coolant run through there anyway?

 

I did this on other vehicles years back and rather than capping the ports I chose to turn them into a loop for the coolant.
To prevent the throttle body from freezing shut in cold weather.

 

Your welcome. Not really sure except for heat soaking your TB. Ran this both on the east coast in negative temps and in the desert where temps are between 100 and 120. No cons only positive are cooler TB temps.

 

That also works. I just chose the samco caps since it looks cleaner. I ran this in negative temps in NJ all year round with absolutely no issues even in cold starts during the winter when the whole outside of the car was frozen over.

 

Hmmm......Thx for this mod, never heard of this talked about before on CL

 

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.

 

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.

 

So you essentially cap off the throttle body and just remove it from the loop. Did you run a new hose eliminating the whole throttle body?

It may be pictured, so sorry if I missed that.

 

Nevermind, you put the caps at the beginning of where the old hose was, and also capped the throttle body.

Thanks for sharing. This is now on my mod list, as well as the rear engine breather mod you shared.

 

I think the IAT is measured at the air box - is there a way to measure temps post throttle body?

 

IAT is measured right at the MAF. If you have a laser temp gun you can measure it wherever you like.