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Former '05er
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Discussion Starter · #1 ·
I've been on this board a minute or two. I haven't seen anyone post about bypassing the coolant running through our throttlebodies. Why is that?

I see lots of threads about being sure to get cold air to the throttlebody, but nobody is trying to cool the throttlebody. It's at 180+F. It's definitely heating the air going through it. Bypassing these things has been high on the list of "first things to do" for years. Why doesn't anybody do this to the tC?
 

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I had done the bypass on the Honda, primarily because the stupid FITV would get wiggy after awhile and the fast idle would never work right (or settle down). I've not gotten around to it in the tC yet, but it's on the list of things to do before I give up the ghost.


The Honda was a bastard because the coolant lines to the FITV and IACV were daisy chained together-- and if you just looped the head back to the block (cutting out the IACV), you were rewarded with the World's Most Inconsistent Idle, because even air blowing past the block would confuse the hell out of the IACV. Unplugging it brought a nice CEL, and locking it out got a ~500rpm curb idle.

God, what a nightmare that was. Maybe I will leave the TB coolant lines alone after all... too many memories.
 

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Discussion Starter · #3 ·
2JZ's don't mind it at all. Rumor has it they don't even freeze up (which is why they do it in the first place.)
 

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the benefit is no more hot coolant running through ur t-body heating up the intake air....

im not doing it on mine simply because i live in ny and i still drive my tc through the winter. it helps warm th engine up in the morning
 

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REWIND

There's channels for coolant to flow through the throttle body? How would you bypass this? Why would a manufacturer build it so that hot coolant is passing through the TB if it detracts from the power of the engine?

Teach me oh wise ones.
 

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I have forgotten all about doing this, thanks!! Did it on my turbo Matrix when I lived in San Diego, move to far No Cal where it it snows in the winter and it worked just fine on pretty cold days.

With the TB behind the engine and out of the main airflow it may actually do very well even in really cold areas. It does snow here on occasion in Far Northern Oregon but I will give it a try and report back over time how it goes:)

Rick
 

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they put it there so that the Idle Air Control Valve doesnt seize up. Also its there to warm the car up faster. because as great is cold air is for performance...too cold and the fuel wont atomize properly and this hurts performance, fuel miuleage etc.
 

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Discussion Starter · #9 ·
There's no IAC on the tC throttlebody. I already checked on that. It's just to prevent the blade from freezing open.
 

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You think a large column of viscous fluid is being heated up by an aluminum throttle body at the speeds that the air is going through there? You are kidding yourelf if you do. Not only does the skin effect say that *maybe* 1 or 2% of the air would rise in temperature a fraction of a dgree centigrade. On top of that, the heat soak in the TB could make the temps rise above the coolant. Likely: no. Possible: why not? There's usually more to a story that what initially appears.
 

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Discussion Starter · #12 ·
All true, however, under most operation, it isn't a large column of viscous fluid, it's pretty small amount of air actually moving through the throttlebody. Cruising hp airflow could easily flow through a drinking straw. Like I said, at WOT, probably not a big deal, but for transient response from part throttle, maybe so. IMHO, certainly a lot more important than some metal tubing supposedly drawing colder air than the OEM airbox. That's really my point: why are you wasting $300 on some piping with a K&N filter when you're still running hot water through your throttlebody?
 

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oh, one more thing. doing this mod could cause what problems? for the tC. I did read all the provided information but, it looked like all the issues are on other engines. what problems could one expect on the 2AZ?
 

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Discussion Starter · #16 ·
Same potential issues. Here in Sac, it might be an issue on our really foggy days in the winter. Then again, it might not because the throttlebody is in a pretty thermally active area.
 
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