coolant passage in the throttle body

[9G]

why? what for? i really can't think of a reason why there is a coolant inlet and an outlet in the throttle body. I thought they were vacuum lines but coolant spilled over when i pulled the line.

Anyone care to explain? Mine is throttle-by-wire if that matters.

[manybrews]

to prevent throttle icing, which could potentially kill you. Particularly important on drive-by-wire systems.

[Its Reu]

thats good to know. 9G do you have a pic of the line your talking about incase i have to see it somewere down the road

[9G]

hehehe. never thought of that. but crap! it can happen! :shock:

I guess i should warm up the car if its really really cold outside just to make sure and make sure to change the coolant when it's due.

As for the pic, all it really is are 2 hoses that goes to your throttle body. You can feel it if you can't see it.

[DOHCstunr]

<div class='quotetop'>QUOTE(9G)</div><div class='quotemain'>why? what for? i really can't think of a reason why there is a coolant inlet and an outlet in the throttle body. I thought they were vacuum lines but coolant spilled over when i pulled the line. Â*

Anyone care to explain? Mine is throttle-by-wire if that matters.</div>
coolant goes to mitsubishi throttle bodies because of the fast idle air valve.
FIAV
ever notice that when you start the car(when coolant is cold i.e. in the morning or after sitting for an hour)
your idle is high, 1200-1400
this is because of thre fiav.

THE WHY
:arrow: when your engine is cold it draws a weaker vaccum which makes it more difficult to sustain a typical idle.
:arrow: when your oil is cold it operates at higher pressures. it is very thick and harder to pump. this puts a load on your oil pump and has a similar effect to turning on the a/c compressor, or cutting the wheel and the power steering pressure causig the engine speed to drop(just more drag on the crank) _when my oil temp is 50 degrees at startup my oil pressure is 65 psi at idle. then when my oil temp is up to 185 the oil pressure has dropped to around 15 psi at idle(oil is more fluid and thinner)
since the crank turns the oil pump, the engine can stall or idle very low and rough because of the extra load under low vaccum
:arrow: the higher idle allows your coolant to warm up faster aiding in satisfaction and comfort of the driver.
:arrow: the higher idle aids in oxygen sensor warm up(in tandem with the built in o2 sensor heater) increasing fuel efficiency and lowering emmissions by allowing it to reach closed loop mode sooner.
:arrow: the higher idle aids in warm up of the catelytic converter helping to reduce emmissions.
:arrow: the higher idle allows the oil, coolant, and mechanical components of the engine to reach operating temperatures sooner.

the HOW
inside the throttle body in the FIAV there is a wax pellet. the coolant circulateds past this pellet and a corresponding mechanism. when the coolant is lower than a desired temp the mechanism opens a passage that bypasses the throttlebody. this allows more air to get into the engine at closed throttle effecdtivly raising the engine speed.(this is your cold high idle)
when the coolant is warmed up(i think around 180 degrees) the wax pellet melts and the mechanism closes off the passage. then your idle returns to its normal state, and is completely under control of your idle air controller.

this method is just a very simple, very reliable, and very inexpensive mechanical method of combatting a cold motor. its been done this way for years.

another method to get the same results.
since the ecu can see the coolant temperature. it is going to know when the idle needs to be high and when it needs to be restored to normal( the obd2 ecu's can check that the cat is warmed up, that the o2's are warmed up, even what tempurature the coolant is)
so other vehicle manufacturers(not all) achieve the fast idle mode through an electronically controlled solenoid. when the engine is cold the solenoid ids open, when its warm the ecu closes the solenoid.
very simple. the solenoid controls the air that is bypassing the throttle plate.
however this is more expensive, solenoids are not cheap especially when compared to the cost of a foot of coolant hose.
also solenoids wear out/fail.


so there you have it. hope that answered your question.
here is a pic of the fiav and its passages

the passages and spring on the left are a part of the fiav system. the passages on the right are for the iac.

[9G]

hehe thanks . ^^ so does the 7G and 8G have them too?

[DOHCstunr]

<div class='quotetop'>QUOTE(9G)</div><div class='quotemain'>hehe thanks . ^^ so does the 7G and 8G have them too?</div>thats why the coolant goes there. so yes.
thats the pic of an 2g fiav. exact same as the 1g eclipse and 7g galant fiav.

[Its Reu]

wow that was a lot of info to take in at once very informative though

[DryBear]

Most excellent post!

[bronxbombr]

<div class='quotetop'>QUOTE(wanderingpinoy)</div><div class='quotemain'>Most excellent post!</div>

cosigned.

[Its Reu]

quick question, since we have drive by wire how do we clean our TB? is it still the same procedure as a regular TB?

[DOHCstunr]

<div class='quotetop'>QUOTE(Its Reu)</div><div class='quotemain'>quick question, since we have drive by wire how do we clean our TB? is it still the same procedure as a regular TB?</div>

pull the intake hose off, i suppose you'll have to use your finger to open the throttle plate from the inside since there will not be a throttle rotor to work with. be sure to spray ilerally on the shop rag NOT INTO THE THROTTLEBODY. and jsut scrub away with the rag.
wipe the edges of the plate, the bore of the throttle body, and the face of the plate on both sides, front and back.
put everything back together and let it sit for 5-10 minutes to give everything a chance to evaporate before you start it.

[Its Reu]

ic ic im going back to my old auto shop today to finish dropping my friends integra :shock: and im gonna ask my old auto teacher if he knows any other ways to clean it out

[9G]

on mine, i just unbolted the throttle body and didn't bother removing the lines. i pulled one but put it right back after seeing the coolant. There is really a good room to work with so mine went easy. I just pushed the throttle plate and started wiping off everywhere. Make sure to disconect the wire harness though cause weird things happens and you might loose a finger.

[manybrews]

the drive-by-wire cars do NOT have the fast idle valve in them. the only mitsus to not have them ever.

[DOHCstunr]

<div class='quotetop'>QUOTE(manybrews)</div><div class='quotemain'>the drive-by-wire cars do NOT have the fast idle valve in them. Â*the only mitsus to not have them ever.</div>interesting

[manybrews]

<div class='quotetop'>QUOTE(DOHCSTUNR)</div><div class='quotemain'><div class='quotetop'>QUOTE(manybrews)</div><div class='quotemain'>the drive-by-wire cars do NOT have the fast idle valve in them. Â*the only mitsus to not have them ever.</div>interesting</div>
they also dont have any type of seperate idle control motor, but why would they?

thats half the point of drive-by-wire throttle.... much easier for the PCM to control during any circumstance. Integrated cruise control, idle control, traction control, emission control, auto tranny control, etc.etc.

[SkylineG1]

Are the 8G drive-by-wire cars?

[DOHCstunr]

<div class='quotetop'>QUOTE(SkylineG1)</div><div class='quotemain'>Are the 8G drive-by-wire cars?</div>no

[Tech_Greek]

The DBW system also results in less cluter of the engine bay and intake tract in general imho, especially for those people who love the Cold Air Intakes...oh wait ours OEM are CAI! hah