Coolant to throttle body?

I just finished building the motor for a friend's car and was put back together a few days ago.
I did bypassed the coolant lines going to the throttle body.
Has this caused any idling issues for anyone?
The car is idling to high and i am not sure if its the coolant bypass or the idle control valve.

 

Yes, it WILL cause problems, because the FAIV is going to take FOREVER to warm up. You should never remove the coolant lines without also blocking off the FAIV. Either pop out the freeze plug under the FAIV and screw the FAIV thermovalve in the whole way, or remove the FAIV from the TB and JB Weld ONLY the FAIV section closed, NOT the ISC section, or you will have no idle control. There are also companies like JB Fab that make blockoff plates for just the FAIV section.

 

[boostedinaz]

If you just didn't hook up the lines it can cause high idle. There are a few ways to block off the passages, one is a plate that keeps the IAC functioning but blocks the FIAV.

FIAV block off plate.

The other is what I usualy do and that is to fill the ports for those coolant lines with JB Weld. You just take off the lower portion of the throttle body and clamp a smooth piece of metal to it. Then mix up the JB Weld and poor it through the hose fittings. Let it sit over night and reinstall.

In either case taking out the screws to seperate the two halfs of the throttle body will be the hardest part. They are SUPER tight and the heads of the screws seem to be really soft. When ever I pull them apart I get some allen head bolts and use those for reassembly.

 

alright, i will route the coolant lines back into the throttle body and see if it helps with the idle.
thanks for the advice.

 

[belize1334]

The TB has two systems for controlling the idle. The ISC is computer controlled whereas the FIAV is passive and works based on coolant temperature. If you just bypass the coolant lines then the FIAV stays in "cold" mode and the idle will never drop. To do it properly you need to block the airflow through the FIAV so that it is completely disabled. The ISC will then take total control of idle conditions. This is still a very functional arrangement as the ISC is perfectly capable of handling cold-start conditions and keeping the rpms up when appropriate. The simplest way to deal with this is to get an FIAV block-off plate that leaves the ISC functional. You can also build one yourself if you'd like. The basic function is that they share a common air source which is split into two to run to the two systems. You need a plate which blocks the FIAV outlet but leaves the inlet and the ISC outlet unrestricted. Then you can remove the bead/spring from the lower half of the tb, bypass the coolant lines, and reassemble.

 

[boostedinaz]

Quoting elhalisf:
alright, i will route the coolant lines back into the throttle body and see if it helps with the idle.
thanks for the advice.



Honestly I would just bypass it. The little wax pellet tends to bad over time causing odd idle issues and it can't be rebuilt. Here in AZ it doesn't get cold enough to really need it and even when it is chilly out the ISC will raise the idle enough to aid in warm up. None of my DSMs or GVR4 had a working FIAV by my own doing and all of them had a rock solid idle.

 

[belize1334]

Seriously, I see -25*F during Montana winters and the ISC is more than enough to compensate for a blocked FIAV. Order a block-off plate from JNZ or MAP or one of those tuner shops and you won't regret it.

 

Quoting boostedinaz:
The other is what I usually do and that is to fill the ports for those coolant lines with JB Weld. You just take off the lower portion of the throttle body and clamp a smooth piece of metal to it. Then mix up the JB Weld and poor it through the hose fittings. Let it sit over night and reinstall.



I don't think this is right. Its not the coolant part that you need to block with JB Weld. Its the section of the FAIV that allows air to bypass the throttle plates. I believe its the section I colored in blue:

The section to the left you want to leave open, so the ISC can still function.

Quote:
In either case taking out the screws to separate the two halfs of the throttle body will be the hardest part. They are SUPER tight and the heads of the screws seem to be really soft. When ever I pull them apart I get some allen head bolts and use those for reassembly.



I HIGHLY recommend using a good impact type screw extractor to remove them. Otherwise you WILL strip them out.
Sam at RRE actually did a nice little writeup on Tuners about how to just pop the freeze plug out and turn the FAIV screw in the whole way to disable it. You could do that without having to separate the FAIV from the TB:
click

 

The FIAV bypass plate works great. The installation however is a PITA. Those Philips head screws can be destroyed in a heart beat but I was fortunate to have my dad around who is an absolute witch when it comes to getting stuff like that undone.

 

[BoostedAWD91]

if the screws wont come out and get stripped trying to unscrew, i have found that vicegrips help to get them out.

 

[belize1334]

Needle nose vise-grips work well. Also, if you have a drill you can use a bit that's just slightly larger than the screw diameter. It will center in the phillips head and you can basically drill the head off of the screws. Then you pull the bottom off which exposes all of the screw shaft that was previously inside the lower housing. Grap that with pliers and it's game over.

 

That's why I think if I had it to do again I would just pull the TB off the car, pop out the freeze plug, turn the screw the whole way in, and silicone the freeze plug back in place. Those screws are such a pain! /ubbthreads/images/graemlins/mad.gif As I said though, my good impact driver/screw extractor from Harbor Freight made short work of them, and none of them stripped out.