2G FIAV block off

[4G Power]

I just put my car back together, after putting a new head on it. I decided to just loop the FIAV coolant lines together, and then I put screws in the lines coming out of the throttle body. The car idles really high once warmed up but I'm not sure if it's because of this.

I read that if you don't use a block off plate it creates a huge vacuum leak similar to what I'm experiencing. BUT, does that still happen since I capped the lines going into the throttle body and then looped the coolant lines?

 

[92AWDHX40]

http://www.dsmtuners.com/forums/mai...9-fiav-leaking-boost-into-cooling-system.html


this may help I never removed my fiav personally.

 

[steve]

The car idles really high once warmed up but I'm not sure if it's because of this.

I read that if you don't use a block off plate it creates a huge vacuum leak similar to what I'm experiencing. BUT, does that still happen since I capped the lines going into the throttle body and then looped the coolant lines?

FIAV = Fast Idle Air Valve.

The coolant running through the valve causes it to close as the engine reaches operating temp. If you disconnect the coolant lines the valve stays open and you get a high idle. Not a vacuum leak, just extra bypass air that shouldn't be there once the engine warms up.

 

[SaulHudson]

FIAV = Fast Idle Air Valve.

The coolant running through the valve causes it to close as the engine reaches operating temp. If you disconnect the coolant lines the valve stays open and you get a high idle. Not a vacuum leak, just extra bypass air that shouldn't be there once the engine warms up.

Does this mean if you don't run coolant you need a fiav bypass plate or do you need to do the RRE valve mod?

 

[4G Power]

FIAV = Fast Idle Air Valve.

The coolant running through the valve causes it to close as the engine reaches operating temp. If you disconnect the coolant lines the valve stays open and you get a high idle. Not a vacuum leak, just extra bypass air that shouldn't be there once the engine warms up.

thanks. that makes sense now.

 

[steve]

Does this mean if you don't run coolant you need a fiav bypass plate or do you need to do the RRE valve mod?

Yes, that's what it means.

 

[spyderdrifter]

So if my car has a fluctuating idle, regardless of where I have the BISS adjusted to, should I be looking at the FIAV as a potential candidate for it? I've read so many articles about idle surge and how to fix it and such, but I don't have an idle surge problem, at least I don't think I do. Mine will idle 3-400rpms back and forth from 800rpm. All at what seems to be random times to me. It's not a huge issue, just OCD likes to kick in and it annoys me.

If this is the case, then what would the RRE FIAV mod essentially do?
http://www.dsmtuners.com/forums/articles-intake-exhaust/320951-fiav-adjustment-disable.html

 

[basshead]

Before starting to tear things apart log the following items:

Engine coolant temp
ISC steps
Idle switch
Throttle position
RPM

Warm up the engine.
What you should see when stepping on the throttle is:
1 - TPS, ISC steps, and RPM climbing.
2 - Idle switch changing state.

If 1 and 2 checks out OK then you have a big air leek past the FIAV. This is due to the fact that the FIAV is still open just as it will be on a cold engine start.

You have several options to remedy this. Some of them are already written in this thread.

But you could also tune the ISC step maps if you have some sort of tuning solution.

I really cannot see any benefits of removing the FIAV. That is on a fully working unit.

 

[steve]

Good advice but I want to dwell on the statement that in this case the problem isn't an abnormally high idle but a low, almost stalling, idle. FIAV not closing wouldn't seem to be a first order problem. So logging the operation of the engine the first step to diagnosing the issues as Kim has suggested.