Idle Air Control Valve removal

mtek · April 17, 2009, 11:37:36 PM

I hear that some people have removed the ICV and have netted some performance gains - some extra psi's from the charger...
What do you reckon?

Appreciate any answers!

PeteG40 · April 18, 2009, 09:32:36 AM

some people have done a mod on this on g60s but not g40s

Glader Poison · April 20, 2009, 01:14:02 PM

It's quite a common mod in Portugal and unfortunatelly I haven't found reports of being done elsewhere.

The ISV is completely removed from the car and the two holes (one in the inlet manifold and other on the plastic hose) are sealed. The idle stays a bit unsteady at cold but after one minute or so it stabilizes.

I haven't done this mod but it's widely said the car behaves a lot better and the pressure reading increases.

I sure would like to read some reports of other experiences outside Portugal!

G-reets,
Bruno

Ä‘uro · April 21, 2009, 08:01:43 AM

Quote from: Glader Poison on April 20, 2009, 01:14:02 PM
It's quite a common mod in Portugal and unfortunatelly I haven't found reports of being done elsewhere.

The ISV is completely removed from the car and the two holes (one in the inlet manifold and other on the plastic hose) are sealed. The idle stays a bit unsteady at cold but after one minute or so it stabilizes.

I haven't done this mod but it's widely said the car behaves a lot better and the pressure reading increases.

I sure would like to read some reports of other experiences outside Portugal!

G-reets,
Bruno

Can y. put some pics?

Glader Poison · April 21, 2009, 12:45:03 PM

Can y. put some pics?
[/quote]

Sorry don't have any pics but there's really nothing to see because the ISV sit's under the inlet manifold on the right side and has two small hoses, one connects to the inlet manifold (under, not visible) and other to the big plastic tube (under, visible) that goes to the throttlebody.

I haven't done this mod because I don't like having my idle unsteady even just for one minute but a lot of people don't think twice and do it!

mtek · April 22, 2009, 03:01:26 PM

Excellent explanation Bruno! Although with some pics it'd be sweet!

As Bruno said this mod seems to be widely spread amongst Portuguese G40 owners and as usual the Portuguese show their experimental skills to the 'civilized' world...

cheers

Andy · April 22, 2009, 05:16:18 PM

On G60s this is a common mod because the idle control valve is ECU controlled, and the ECU uses it to bleed off boost above a certain limit. If you've got a ported 'charger on a G60 and a small pulley then blocking off the IACV will give you more boost.

On a G40 it won't gain you anything, as it doesn't work the same as a G60.

The G40's valve is a dumb valve, not connected to the ECU. It simply allows air to bypass the throttle butterfly through an apperture that opens and closes based on the temperature of the unit - there's a simple bi-metallic strip within the valve that does this. That's also why it's bolted to the water hose at the back of the block, and the two wires going to it simply turn on an internal heating element when the ignition's on.

If you've got a G40, leave it on, it won't make your car any faster by removing it.

Glader Poison · April 27, 2009, 04:03:03 PM

Quote from: Andy on April 22, 2009, 05:16:18 PM
On G60s this is a common mod because the idle control valve is ECU controlled, and the ECU uses it to bleed off boost above a certain limit. If you've got a ported 'charger on a G60 and a small pulley then blocking off the IACV will give you more boost.

On a G40 it won't gain you anything, as it doesn't work the same as a G60.

The G40's valve is a dumb valve, not connected to the ECU. It simply allows air to bypass the throttle butterfly through an apperture that opens and closes based on the temperature of the unit - there's a simple bi-metallic strip within the valve that does this. That's also why it's bolted to the water hose at the back of the block, and the two wires going to it simply turn on an internal heating element when the ignition's on.

If you've got a G40, leave it on, it won't make your car any faster by removing it.

Very good and technical explanation and it makes sense to me, otherwise I'm sure there would be an alternative ISV like on PG engines. To be honest, and I've asked my friends to show some data that proves the so said increased boost and engine response and so on but nothing to date. I think it's one of those psycological things!

G-reets,
Bruno

hayesey · April 27, 2009, 04:40:26 PM

QuoteI think it's one of those psycological things!

I agree, placebo effect! The only reason I could see for an increase in boost by doing this on a G40 is if the ISV casing was split and causing a boost leak when it was fitted or boost leaking from the hoses connected to it.