Idling problem

[vijay]

Hi,

 

Trying to sort out my high idle problem and have narrowed it down to the AAC part of the IAA unit as when I disconnect the connector the idle drops back down.

 

I think it might actually be a boost leak as I can hear a hiss when the connector is back on, can anyone shed any light on this?

 

Also, what is the actual point of the AAC? What harm will it do if it's left disconnected?

 

Cheers

 

Vijay

[Guest Steve E]

Hi,

 

Trying to sort out my high idle problem and have narrowed it down to the AAC part of the IAA unit as when I disconnect the connector the idle drops back down.

 

I think it might actually be a boost leak as I can hear a hiss when the connector is back on, can anyone shed any light on this?

 

Also, what is the actual point of the AAC? What harm will it do if it's left disconnected?

 

Cheers

 

Vijay

 

Vijay, the auxiliary air control (AAC) valve needs to be connected and operating correctly to maintain the engine idle when the throttle bodies are closed. You can see how it works by disconnecting the power feed and starting the engine from cold; the engine revs will drop out within a few seconds of startup

 

If you connect the conzult, you can see the percentage reading for this control valve which I think should be around 25-40 percent. You can manually adjust the rate at which the AAC operates and this should reduce or increase the idle speed.

 

If the reading is higher than 40% at operating temperature then you may have a small vacuum leak.

 

Steve

[vijay]

Hi Steve,

 

It's up at 70% wether it's connected or not.

 

Vijay

[Guest Jeff TT]

Vijay, from your description it would appear the base idle is too low, this means the idle valve has to maintain a high opening at all times, this will be the hissing noise you can hear when the valve is connected as the air goes through the unit.

 

The correct opening setting for the aav with a warm engine should be as close to 15% as you can get ( when using a ConZult)

 

There are a few things to consider that can be contributing factors to your problem.

TPS setting, timing, throttle balance and of course base idle, only after all of the former have been checked then adjust the base idle,without a conZult to turn the aav off, the easiest way is with the engine warmed through but switched OFF, turn the base idle screw ( located on the passenger side (by the battery) of the aav)anti clockwise half a turn. Then start and run the engine for 30 seconds. switch back off and turn again. repeat this process until the idle is steady and can be revved up and throttle snapped closed and the engine returns to a nice steady idle without dipping too low.

 

If you over adjust the idle will be too high, also take care to not undo the screw too far as it will come out of the housing, aim for the screw to be around the middle of its adjustment as a start point and make fine adjustments from there.

 

Hope that helps

 

Jeff TT

[AndyP]

I belive the ACC has a 'default' setting of 70% if the ECU can't detect it, so you could have faulty wiring/connection to it. Mine seems to do this occasionally.