coolant lines thru throttle body and.... - Toyota 4Runner Forum

baja1 · 02-08-2017, 05:57 PM

whats the purpose of coolant thru the TB and is the hose into the idle valve vacuum or just air?
thank you! trying to track down the ol' high idle thing!

thegipper · 02-08-2017, 07:02 PM

Coolant lines through the TB is usually for helping to warm up the TB in cold climates. It's often useless and many people bypass it on some motors. I had a leak on my grand prix from the coolant line to the TB and I just bypassed it.

It's also counter productive when it's warm out and unnecessarily heats up the air through the TB, again, why many people bypass it.

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etc. · 02-08-2017, 07:17 PM

Helps the TB from icing up.

alumarine · 02-08-2017, 09:52 PM

I think it's more for preventing the throttle plate from icing up which can even occur at temperatures above freezing.

I don't think it heats the air up significantly.

baja1 · 02-09-2017, 12:59 AM

who knew? thanks gentleman! I'm a less is more kind of guy, the more I can delete the less there will be to troubleshoot, I understand all these systems are in place for a reason though! thanks!

rallypoint_1 · 02-09-2017, 02:39 AM

I have them bypassed on my Civic and Accord. I also read that the warm/hot TB helps atomize fuel.

phattyduck · 02-09-2017, 04:43 PM

Quote:

Originally Posted by etc.

Helps the TB from icing up.

Keep in mind the TB can freeze up at temps above freezing. The air passing through the throttle body in a near-closed position goes to very low pressure, thus lowering temps. Lower temps + possible moisture in the air can freeze up the throttle body.

I've never had a problem with it (bypassed on multiple cars that I have driven in temps below freezing) but it is technically possible. I left it in place on my 4Runner though... not really looking for 'more power' from little things like that on the 5vz.

The other line off the throttle body goes to the 'air assist' for the fuel injectors. See this thread for diagrams: How to Disable Injector Air Assist

-Charlie

Sparky115 · 04-19-2022, 08:40 PM

I have 2000 4runner, 350k miles. What a pain to get to these things. Spring loaded clamps is the only way to go. If you have to replace the hose do not cheap out, get new clamps. You don't want to have to go back in later.

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