Idle Control Valve - Pre Or Post Boost?

[M@tt 77]

a little query has popped up during my CTI project thread which i thought i'd split into a seperate thread as it may be easier to find for future reference.

 

on the XM engine i am using for my turbo conversion the feed for the idle control valve comes from a take off on one of the pipes that goes from the intercooler to the throttle body. Now does this mean that there might be a possibility that the idle control valve when open is subjected to pressurised airflow on certain occasions??

 

On various other conversions including the GTI6 SC kits it can be seen that the the idle control valves get it's feed from atmospheric air instead.

 

My question is does it make any difference what so ever?

 

And what exactly controlls the idle control valve? is is a combination of engine RPM and tempetrature? i'm just wondering if there are going to be occasions where you would get faster than normal airflow still from the turbo spinning down once off throttle than you would at idle from the pre boost side? and so is the ECU programmed to take accoutn of this?

 

I just thought i'd throw it out there to see if anyone else has any opions/experience

 

Cheers

 

Matt

Edited November 6, 2008 by M@tt

[Tom Fenton 1,542]

Main question is, how was it plumbed as standard?

 

Other than that it depends on your ECU I suppose. The emerald has the facility to drive the idle valve shut above a set point (revs I think) to prevent boost being able to find its way through. Not sure on the DTA I'm planning to use. However my plan was to take air from the inlet to the turbo. I will also tee in recirc air from the dump valve here.