what is the purpose of coolant in intake

[XxrusianxX]

I have seen this on many cars, coolant lines going to the throttle body. I have always assumed it was to heat the intake air for better combustion. Anybody know for a fact. Also is there a way that coolant can leak in to the intake manifold due to that?

 

[Bluebyu96Tsi]

The coolant lines running to your throttle body is for the Fiav. It keeps your rpms slightly higher during cold startups until the little wax pellet inside the valve starts to melt with your rising coolant temperatures, resulting in your rpm falling to a normal level after warmup. Warm or hot air in no way will help your combustion . Hot air is a big no no for combustion. Do a couple quick searches or go to vfaq for a little more info man. Many people plug the fiav and bypass the coolant lines entirely. Hope this helps you.

 

[XxrusianxX]

The coolant lines running to your throttle body is for the Fiav. It keeps your rpms slightly higher during cold startups until the little wax pellet inside the valve starts to melt with your rising coolant temperatures, resulting in your rpm falling to a normal level after warmup. Warm or hot air in no way will help your combustion . Hot air is a big no no for combustion. Do a couple quick searches or go to vfaq for a little more info man. Many people plug the fiav and bypass the coolant lines entirely. Hope this helps you.

This helps, thanks.

 

[staticbrainwash]

It also helps circulate warmpth through the TB so that the TB plate doesn't freeze shut.

 

[xveganxcowboyx]

^^^ That's the reason I've always heard (though it seems pointless, because it would only help AFTER the car was warm and running)

 

[pnishr]

^^^ That's the reason I've always heard (though it seems pointless, because it would only help AFTER the car was warm and running)

It's not pointless, because you are SUPPOSED to let the car heat up before you drive it. and until you're driving it, the throttle plate is closed, and possibly frozen. Though few people let it warm up these days...

But, I hadn't heard that before. Just the wax-pellet/idle speed thing. hmph.

 

[XxrusianxX]

TB freezing???? What??? Has anybody ever had a problem with that?

 

[oldman]

First I ever heard of it. There are plenty of people running with FIAV and coolant lines blocked off and I have never, ever hear one single case of a frozen TB plate. however, I will keep mind open and give you an opportunity to prove it or retract your statement.

 

[staticbrainwash]

I don't know for a fact, but i read in many places on here that for people in colder climates need to leave the FIAV because of the possibility of the tb seizing. I don't remember where it was, but if i'm wrong ill own up to it.

What the real reason then? Just the idle speed on cold start? If thats the case and it's ok to block it off count me in!

 

[oldman]

There is no difference between a functioning FIAV or keeping the throttle slightly open during warm up. Blocking off the FIAV is usually done to solve possible causes of idle surge due to a defective FIAV or to prevent it from happening in the future.

 

[staticbrainwash]

So are there any ill effects to blocking it then? Or rather, is there a problem with not having an increased idle on start up? The only thing i could see is maybe warm-up taking a little longer.

 

[oldman]

Correct but I would say leave it alone if it's working fine.