Please Help *urgent*

[calais25t]

I desperately need to know what this is, I am in the process of installing my new plenum which has very limited outputs for vacume etc.

I need to know what this part does and if its neccesary to hook up or just leave it diconnected.

Thanks in advance any help appreciated.

[calais25t]

Whoops forgot to add its on an RB25DET series 2 and the part sits just below the plenum runners.

[SteveL]

Think if it as the device that provides the cold engine fast idle equivalent of a carby car with a choke. You need to have it connected.

Edited June 24, 2006 by SteveL

[crack]

air regulator, aka an iac (inlet air control) valve. needed for cold starts.

[calais25t]

Well what are the two at the back of the plenum for.??

Im running an after market computor and it dosent even seem to be hooked up anyway?

[calais25t]

Theres 2 valves on the back of the plenum, One aac? and the other I suspect is air-con idle up so why the need for 3 seperate valves?

[R33S2]

My microtech has the aircon idle plug unplugged.

[crack]

Theres 2 valves on the back of the plenum, One aac? and the other I suspect is air-con idle up so why the need for 3 seperate valves?

i think the japs had a thing for idle control. especially in the cold (below zero) weather

[calais25t]

Bump.

Come on guys I need to know if its necessary for my engine to run.

From what I can tell my after market computor isnt even plugged into it anyway.

Do I need to plum it in or not?

[Sydneykid]

Bump.

Come on guys I need to know if its necessary for my engine to run.

From what I can tell my after market computor isnt even plugged into it anyway.

Do I need to plum it in or not?

What throtte body are you using?

cheers

[race_snooze]

mine has been disconnected since i got the car 3 years ago, pain in the arse to start when cold but once it kicks over its fine.

[calais25t]

What throtte body are you using?

cheers

Im using an XF throttle body and also my computor dosent run a throttle position switch/sensor.

Its an EMS stinger if that helps.

Edited June 26, 2006 by calais25t

[Sydneykid]

Im using an XF throttle body and also my computor dosent run a throttle position switch/sensor.

Its an EMS stinger if that helps.

The common solution is to use a throttle stop on the XF throttle body to control the idle rpm and piss off all of the ECU controlled idle speed hardware.

cheers

[BHDave]

I ran my rb20 without it for a year or so. Started and idled fine, it would just stall approaching the same speed hump every morning

So i got in the habit of clutch starting it once past the speedhump and it was happy to keep going after that.

[calais25t]

The common solution is to use a throttle stop on the XF throttle body to control the idle rpm and piss off all of the ECU controlled idle speed hardware.

cheers

Could you please elaborate on this sydneykid?

Are you saying not to run any of them including the two on the back of the plenum?

Thanks.

[Sydneykid]

Could you please elaborate on this sydneykid?

Are you saying not to run any of them including the two on the back of the plenum?

Thanks.

You need to talk to your EMS tuner, as to how he wants to control the idle rpm. The standard RB20/25 throttle body closes completely. So the standard ECU (and Power FC) controls the idle rpm by opening and closing various valves that bypass the throttle body. So when it is cold the ECU advances the ignition, richens up the A/F ratios and increases the airflow into the engine to increase the base rpm and give stable idle. Similarly, when the engine is up to operating temperature, the ECU increases the airflow into the engine to increase the rpm for air conditioning, power steering and electrical load.

I haven’t studied the idle control circuitry in great detail, but my simplistic understanding is the ECU open up various different sized valves depending on the idle speed demand for air flow. This is different to many other engines that use a stepper motor to open the throttle butterfly to achieve the airflow changes required.

The EMS’s that I have dealt with don’t have the feature of staged valve openings to control idle to a number of preset rpm's. So the tuners tend to use a throttle stop to hold the throttle butterfly open, then use A/F ratios and ignition retard/advance to achieve idle stability, hot or cold.

So talking to your tuner is always first on the list when looking at idle speed control

cheers

[calais25t]

Thanks mate.