1G removing coolant line from throttle body?

[spitefire1]

i heard that remvoing the coolant lines from the throotle body is a fiav free mod. is this true and will it effect anyhting. will my car runn any diffenet. and what is the reson for doing this. someone please help me thank you

 

[kamronman]

I'm 90% sure that if you remove the coolant lines to the throttle body the fiav won't be able to adjust idle speed acording to the coolant temp sensor on the thermostat housing. Someone correct me if i'm wrong!! trying to help man

 

[tunethis]

Here's some information about doing this. More information can be found by searching this site. There are several write-ups on here about blocking the fiav and removing it's hoses.

First, you have to block the FIAV somehow. Either with a blockoff plate, sealing the TB's fiav port shut or screwing in the spring that opens the FIAV. It you don't block off the FIAV, it will stay open and that creates a massive vacuum leak, high idle and idle surge. There are two coolant hoses connected to the FIAV. One goes in, one comes out. You have to create a "loop" within the factory configuration when you remove them. Meaning, you have to get a longer hose, remove the two coolant hoses and bypass the coolant going to the FIAV all together. Connect one end of the new hose to where the one FIAV hose (left side) use to go to the thermostat housing. Then, connect the other end of the new hose to the fitting on the water pipe where the second FIAV hose (right side) use to go. Re-use two of the four factory hose clamps removed from the old FIAV hoses.

There's no significant performance gain besides a slightly cooler TB since hot coolant no longer flows through the FIAV. A negligible gain at best I would say. I believe the biggest reason for doing this is to fix idle issues some may have because of a FIAV. Some may also remove it just for a cleaner look.

 

[9!'clipseDOHC]

First of all some background. The Fast Idle Air Valve (FIAV) is what causes the car to idle fast on cold starts. This helps the car warm up faster. To do this the FIAV allows more air into the throttle body (TB) until the coolant temp reaches 122F. If you remove your FIAV, your car will idle low when you first start it up. You may have to press the gas to help it warm up and even to keep it running.

If you decide to do this anyways, tunethis is correct. First you block off the FIAV and then you can remove/reroute the coolant lines from the TB. When I did mine I just looped line 1 into the nipple for line 2. It was just long enough so there should be no need to get a new, longer line.

As far as it being a free mod, it can be if you already have some jb weld. Personally I bought a blockoff plate. You can get a blockoff plate at Level Zero Motorsports for $10 bucks shipped and just slap it between your FIAV/ISC and Throttle body. Makes it a $10 mod but it is not permanent in case you change your mind.

Hope this helps!

 

[TSiTalonawd96]

I took the return line completely out on mine the other day and took the inlet line off the throttle body and hooked it up to the other water line on by the housing. Not really a noticeable difference but no idle issues hot or cold.

 

[this_tsi_8urV8]

I removed both lines from under the t-body, and looped the line coming off of the water pipe to the outlet on the t-stat housing. I did use a block off plate.

 

[Boosted98gsx]

I removed both lines from under the t-body, and looped the line coming off of the water pipe to the outlet on the t-stat housing. I did use a block off plate.

If you don't use a block off plate, your car will idle VERY high at stop lights, even when it warms up. You will need to make a block off plate, like above, to block the FIAV ports in the lower TB, so that extra airflow will not bypass the throttle plate.

The downside to this, is you WILL have cold start issues. However, once the car warms up (O2 sensor feeds back) your car should perform properly.

 

[TSiTalonawd96]

I did this and did not use a block off plate. I read on here somewhere that it creates a huge vacuum leak somehow, is this true??

 

[andy4g63]

If you don't use a block off plate, your car will idle VERY high at stop lights, even when it warms up. You will need to make a block off plate, like above, to block the FIAV ports in the lower TB, so that extra airflow will not bypass the throttle plate.

The downside to this, is you WILL have cold start issues. However, once the car warms up (O2 sensor feeds back) your car should perform properly.

^^^ He probably meant FIAV by-pass plate. It allows you to keep the ISC.. The blockoff plate eliminates ISC, so it will be very hard to make it idle without some sort of EMS.

To the OP: Most of times, there are 2 reasons for removing coolant lines from TB...
It actually HEATS UP the incoming air/which is obvious/..
Some times the lines tend to create a coolant leak inside if IM, which isn't good, cause coolant/water is not compressable..

 

[eclipse gsx]

i looped my lines on the thermostat housing and just capped of the tb nipples, so i did not installa fiav block off and my car idles like shit, at stop lights and even turns off so im putting my lines back in order till i buy a fiav block off plate thanks for the info i was thinking it was my tps hahahaha thanks

 

[FactoryChrome]

If you don't use a block off plate, your car will idle VERY high at stop lights, even when it warms up. You will need to make a block off plate, like above, to block the FIAV ports in the lower TB, so that extra airflow will not bypass the throttle plate.

The downside to this, is you WILL have cold start issues. However, once the car warms up (O2 sensor feeds back) your car should perform properly.

That is not correct. You can screw the adjustment under the freeze plug all the way clockwise to shut the valve permanently... The proper adjustment of your BISS and a functioning ISC will keep your idle proper.

I did the same thing to my car as Sam from RRE explained in another thread and had zero cold start issues.... and my idle rpms were exactly where I put them in relation to the CTS.

 

[Boosted98gsx]

^^^ He probably meant FIAV by-pass plate. It allows you to keep the ISC.. The blockoff plate eliminates ISC, so it will be very hard to make it idle without some sort of EMS.

To the OP: Most of times, there are 2 reasons for removing coolant lines from TB...
It actually HEATS UP the incoming air/which is obvious/..
Some times the lines tend to create a coolant leak inside if IM, which isn't good, cause coolant/water is not compressable..

Well since we were talking about the FIAV, I assumed that would be understood. Keeping the ISC would still be optimal and necessary for a street car.

 

[hsk8te2006]

Here's a question for the tech's in this thread...

My car is having idle issues. Two weeks ago, it ran fine. A week ago, it wouldn't idle below 1500 rpms. Now, it idles fine at the start, but as soon as the car starts to warm up, it stalls everytime I put it in neutral/clutch-in unless I idle it manually using the throttle.

Also, if I re-start the car while still warm, it stalls out just the same.

I'm guessing either my FIAV or my ISC is having issues, but I'm not sure which one. Or maybe something else entirely? Any thoughts?

Thanks!
Jonathan

PS My ISC tests out ok when cold per http://dmtalon.v8eaters.com/ISC.html.

 

[snowborder714]

I'd test the ISC first, as it's quick and easy.
DmTaLoN's Idle Speed Control Test/Fix Page!

 

[hsk8te2006]

I already did, as above... the ISC tested fine.

 

[9!'clipseDOHC]

What have you done to the car in the last 2 weeks? Have you changed anything? Replaced anything even if it seems unrelated? There are other things that can cause your car to shut off when you push the clutch besides the throttle body sensors. I know that if you have air in your coolant lines that can cause stalling. I would check that first. Let me know if you messed with anything.

 

[hsk8te2006]

A list of recent changes (last 2 months)
-Oil change
-Installed ProSport Gauges oil catch-can in crankcase breather line
-Installed new boost controller piping and filter (same configuration as before.)
-Cleaned out the MBC and its lines

I tried to run the car for a minute with the crankcase breather hose detached to test if the catch-can was involved, but it made no difference... car still stalled.

Also... my coolant system is full with no leaks.

I did recently hear from Midas that my oil cooler lines were leaking oil onto the ground a tiny bit (they recommended replacing the lines when I get my next Timing belt change in 10k miles.)

 

[snowborder714]

Have you checked for boost leaks recently?

 

[hsk8te2006]

As of a year ago it held 8 PSI completely, and had only a very tiny leak somewhere in the area of the TB. It still boosted up to 15 psi when running no problem.

I currently have the TB off the car and I am replacing the TB shaft seals and the biss-screw O-ring to try and solve the leak. I will re-test in a day or two when I put the TB back on.

It still seams to me like something that used to let air into the engine at Idle is no longer working correctly, and if I need to replace anything on the TB, I'd much rather do it now while the TB's off the car already.

PS The car runs fine when in gear or being idled manually (via the throttle.)

 

[9!'clipseDOHC]

Check out this thread, irradic idle. There is a lot of good info!

It could be a problem with your ECU but I would check all the easy stuff first.

Since you are replacing your BISS, check out this link on how to correctly set it once you reinstall it.