Anyone have the problem with the ac making the engine idle hunt??

[painterdave72]

My car is idle hunting like crazy with the ac on.. it doesnt do it if just the fans come on or with any other accesory on.. I have josh bengstons cams and also have the uk stainless exhaust.. i am also running open loop because it runs so much better.. thanks for any suggestions... Dave..

[Bitsyncmaster]

Since your running open loop lambda, I bet it's just your idle motor is sticky. You can also adjust your curb idle screw differently so the idle motor is running in another spot.

[painterdave72]

hhmmm maybe.. the motor is relativly new. maybe five years old.. i will try to spray it out with some silicone or something similar.. my car does idle hunt a bit when cold also but usually no more than a minute..would u adjust the idle speed screws bitsync??????

[Bitsyncmaster]

hhmmm maybe.. the motor is relativly new. maybe five years old.. i will try to spray it out with some silicone or something similar.. my car does idle hunt a bit when cold also but usually no more than a minute..would u adjust the idle speed screws bitsync??????

When you change the curb idle or bypass adjustments it will make the idle motor run in a different setting. Because your getting more or less fuel at the idle speed the idle motor has to compensate for that change.

Of course if you open the curb idle to far then you may loose closed loop idle control because the idle motor would be fully closed.

Just turn the curb idle (lower screw) out (CCW) or in (CW) a half turn and see if that fixes it.

[David T]

If you are running cams with a lot of overlap you do not have a lot of vacuum at idle. It will reduce the amount of power at idle and make the idle quality bad. Adding additional load (the A/C) only makes things worse.
David Teitelbaum

[Bitsyncmaster]

Another reason you need to run a higher idle RPM with cams. If only someone had an adjustabe idle ECU.....:coffee:

[painterdave72]

I am running without the o2 sensor bitsync.. i think that is open loop.. i will try to adjust the bottom screw a half a turn tomorow and clean the idle speed motor out.. any other suggestions?? thanks Dave.

[Bitsyncmaster]

I am running without the o2 sensor bitsync.. i think that is open loop.. i will try to adjust the bottom screw a half a turn tomorow and clean the idle speed motor out.. any other suggestions?? thanks Dave.

Yes without the O2 sensor your lambda is open loop. But if your running the idle ECU and it's working then the idle system is closed loop.

Closed loop is just a term used when a system is adjusting a magnitude of output depending on the magnitude of input. Open loop is when those adjustment conditions are stopped.

[DMCMW Dave]

Don't use silicone spray anywhere near the intake of an engine. It will kill the O2 sensor.

[painterdave72]

thanks Dave..i will use pb blaster or something like that...

[Ryan King]

Mine has this problem. Badly. Can someone please link me to photos of it and some better instructions on how to clean it?

[painterdave72]

Okay bitsync.. i cleaned the idle speed motor and it made no difference.. i will try to adjust the screw a half a turn tomorrow.. do u think in or out is better??? and any other suggestions... thanks..dave..

[Bitsyncmaster]

Okay bitsync.. i cleaned the idle speed motor and it made no difference.. i will try to adjust the screw a half a turn tomorrow.. do u think in or out is better??? and any other suggestions... thanks..dave..

I set the curb idle by running the warmed up engine with no loads (no AC, no headlights, etc). Then I slowly turn the screw clock wise until idle RPM increases. At that point your idle system has closed the idle motor fully so it can not adjust it anymore. Then I slowly turn the screw CCW until the idle is back at 775 RPM. Give it a little more CCW movement and lock it down.

[painterdave72]

i tried to set the idle screw and that didnt do much at all either bitsync.. any other suggestions??? could it be some sort of electrical interfercence??? im lost dammit!!!!!!!

[Bitsyncmaster]

You want to be sure your ignition advance solenoid is activated when at idle. Your car will start and run with the timing advanced but will usually cause idle problems.

Lots of ways to check it but the fast way I check it is unplug the connector on the advance solenoid when the engine is idling and you should note the RPM jump up. Most times the idle ECU can still compensate and bring the idle speed back down to normal but sometimes (hot engine no loads) it will stay at high RPMs. Then plug it back in and RPMs will drop and the idle system will bring the RPM back to normal.

You may also hear the "click" of the solenoid as it switches on or off.

Lots of other things can affect idle. The idle system really needs most every thing to be perfect to never hunt.

[painterdave72]

I just checked that... it doesnt click anymore when i have the key on and move the throttle spool.. that is how i have checked them before... do you have a good used one by chance bitysync??

[Bitsyncmaster]

I just checked that... it doesnt click anymore when i have the key on and move the throttle spool.. that is how i have checked them before... do you have a good used one by chance bitysync??

Now is it the switch, solenoid or wiring? Switch is easy to test with a jumper and see if the solenoid clicks.

[painterdave72]

the wire harness is brand new so it shouldnt be that.. i will test them here soon.. how do u test the actual solenoid???

[DMCMW Dave]

The switches go bad more than the solenoids, I've seen leaky solenoids.

Testing - pull a vacuum (with a Mity Vac or your mouth) on the barb normally connected to the engine. With no power applied, it should pull through from the other port. If you apply voltage to the solenoid, it will block the vacuum port.

Test the idle stop switch.

Put a test light on the wiring to the solenoid, it should have power with the throttle closed and no power with the throttle open.

[painterdave72]

I found the prob... the bottom wire had come off the microswitch.. all fixed now!! lol.. hopefully that was the prob with the ac causing the idle too. i will drive the car later!!!