sk88erguy

My idle will increase, then come back down to normal when AC is on. I think its always done it but im just not sure i thought id ask, TIA.

sk88erguy

41/55-Signal from A/C control module -W/W - signal used by ECU to increase idle speed through ISV control when A/C compressor is activated (actually just maintains the idle seed when the extra load from A/C compressor is added to the system during idle)

so, im thinking its ok that it would increase, but is it normal to not just stay at the increased speed?<ul><li><a href="https://forums.audiworld.com/s4s6/msgs/149829.phtml">https://forums.audiworld.com/s4s6/msgs/149829.phtml</a</li></ul>

UrS4boy

It's a machine. Has to get a signal, process the signal, decide what to do and then send a signal to a device to modify the original input (takes time and the control amounts are not perfect) (basically a sophisticated trial and success method).

sk88erguy

my idle has not dropped once, but it will burp every now and then up in RPMs, and i was wondering if the ac is magnifying whatever the cause is? or is the compressor reving the engine up 250 rpm's OK?

Linc's S4

traveling along at 0 on the boost gauge then turn on AC and the needle jumps 2 PSI.

Zwoobah

mine does the same thing. it also bogs slightly when returning to idle w/AC on

sk88erguy

OK good, im thinking its ok it seems normal, it increases smoothly and fall back isn't bad.