Air Conditioning Idle Up.

[CC_GSR93]

So I have had my throttle body cleaned out, which sorted out my previous idle problems on my CC GSR.

However, I cannot seem to fix idle dropping on turning the air con on. It is that bad, that sometimes when changing down a gear or so the car near stalls.

Any Ideas on why my idle isnt going up when the AC is turned on?

I suspect a vacuum leak, but I have no idea how to find them.
Also noticed on my throttle body there are three hoses on the top of it marked "PEA". The "E" hose is disconnected and unused for some reason.

 

[Liberoz]

pretty sure its relay related or trigger to ecu when aircon is or ecu should raise rpm to prevent it from stalling from the extra AC load.
I've never personally had to deal with this issue so someone else no doubt will post the exact fix help.

I have had a hunting issue that has been bugging me for years it will do it weather stationary or in gear the idel hunts when you get to 1,750rpm to 2000rpm its a right pain in the ass when trying to cruise slowly in 10kph traffic and the car jerks back and forward when its hunting between those rpms.

 

[GSR94T]

I have this issue as well but havent had a proper chance to get it checked out

I do also believe it might be related to a relay which should get a signal from the ECU to increase the idle

Now im not sure if this was connected during my engine conversion

The wiring diagram for ECU is available here (taken from another thread)
http://www.mediafire.com/?2guqyy3wl2y

Does anyone here know which wire/pinout should be triggering idle up? and what it connects to?

 

[CC_GSR93]

pretty sure its relay related or trigger to ecu when aircon is or ecu should raise rpm to prevent it from stalling from the extra AC load.
I've never personally had to deal with this issue so someone else no doubt will post the exact fix help.

I have had a hunting issue that has been bugging me for years it will do it weather stationary or in gear the idel hunts when you get to 1,750rpm to 2000rpm its a right pain in the ass when trying to cruise slowly in 10kph traffic and the car jerks back and forward when its hunting between those rpms.

Anyone have any idea what the relay is in the ECU that triggers idle up when AC is switched on? Hopefully it isn't too expesnive to replace...

EDIT: I am on a 1.8 still, so I would not have the issue of the ECU not being connected up properly like GSR94T did.

 

[Liberoz]

Data log it! and look at the fault codes

 

[evopwr]

sounds to me like its time to upgrade to evo sized TB. get a magna one, theyre direct fit and are same size as an evo one.

alex

 

[CC_GSR93]

ECU

sounds to me like its time to upgrade to evo sized TB. get a magna one, theyre direct fit and are same size as an evo one.

alex

Wouldn't this be a ECU issue as opposed to a TB issue?
Also, does anyone know if a Vacuum leak in the air conditioner vacuum line cause these issues?

 

[MatS]

Not sure if it's related 100%, but when i first got my GSR it would stall at traffic lights when the aircon was on.

I pulled off all the vacuum lines, replaced and re-routed them. This solved my problem. The car still drops in rpm when the AC is on (500rpm lowest point), but doesn't stall.

 

[kessen]

Yeah I get this problem too but I've also found mine to be related to the fan speed when the air con is on. If its on full blast with the aircon it gets near to stalling when you change down a gear and let the rpm drop..

 

[Yushman]

i thought this was caused by a fauly Idle control valve.

 

[thirteen]

Any Ideas on why my idle isnt going up when the AC is turned on?

I had this problem too. My idle would drop when I turned on the aircon.
So I went to an Auto-elect, who told me I needed a new ECU...ok then I can live with the idle drop. lol.

Then a while back whilst getting a service my mechanic says
"your idle drops when the aircon is on. You need a new Idle Speed Controller" So we rang Meek, next day, 5 minutes and $110 later my GSR's idling like a dream with and without aircon going. And the idle is perfect to this day. (Cold idle up = 1200-1300 rpm, then idle drops down to 750 rpm when at operating temperature).
When the aircon is turned on the ECU bumps the idle up 200-ish RPM to compensate for the extra load on the engine.

Needless to say I'm not going back to that auto electrician again.

 

[chris123]

I had this problem too. My idle would drop when I turned on the aircon.
So I went to an Auto-elect, who told me I needed a new ECU...ok then I can live with the idle drop. lol.

Then a while back whilst getting a service my mechanic says
"your idle drops when the aircon is on. You need a new Idle Speed Controller" So we rang Meek, next day, 5 minutes and $110 later my GSR's idling like a dream with and without aircon going. And the idle is perfect to this day. (Cold idle up = 1200-1300 rpm, then idle drops down to 750 rpm when at operating temperature).
When the aircon is turned on the ECU bumps the idle up 200-ish RPM to compensate for the extra load on the engine.

Needless to say I'm not going back to that auto electrician again.

How does your car cope with the radiator fans coming on? Mine seems perfect except for when the radiator fans kick in? Doesn't really bother me anymore just interested in seeing if a car with a new ISC would do the same thing?

 

[CC_GSR93]

Valve

i thought this was caused by a fauly Idle control valve.

I have put a new ISC motor on the TB, is the idle control valve separate from the ISC?

 

[thirteen]

How does your car cope with the radiator fans coming on?

doesn't effect it.

 

[chris123]

doesn't effect it.

Hrmm ok then, its an odd one, given the radiator fans are electric if i remember correctly.

 

[thirteen]

Hrmm ok then, its an odd one, given the radiator fans are electric if i remember correctly.

Sorry dude I thought you were asking if my car idles bad/poorly when the radiator fans kick in.

Next time my radiator fans are on I'll take more notice but as it is I've never noticed anything untoward whilst they're going.

 

[philsth]

i thought this was caused by a fauly Idle control valve.

Your on the right track, the 4G93 has an Idle Speed Control Servo ISC which is a stepper motor driven valve.
A stepper motor allows for precise partial rotation ie. it can be turned in partial increments of 360 degrees.
This allows the amount the valve is opened or closed to be variable.

I am actually going somewhere with all this .

What the ISC does is it allows air to bypass the butterfly in the throttle body to increase or decrease idle speed.
By opening or closing the air passage it has the same effect as opening or closing the butterfly.

The ISC is directly controlled by the ECU and sets the idle accordingly, when the Aircon is on it should raise from 750 to 850 (eng at operating temp).

My GSR has always idled around 900-950 with air on. When I first switch on aircon on a cool motor it jumps to 1700 and slowly comes back to 900 ish.

These ISC seem to be a common source problems from the problems that are posted up.

I know I haven't offered a solution but I hope this will point you in the right direction with a bit of background on how the idle system works.

Cheers
Phil