my engine has always flucuated at idle when ac is on and brake pedal is held down. when ac is turned on.idle steps up like it should,but press the brake and rpm go to low idle near stall then back to high idle then low, then high...
Anyone ever had similar problem???(22re)

 

vacume leak somewhere, or leaking booster. When you step on the brake do you hear a squish or sucking noise from the brake area under the dash?

check you vacume hoses in the engine bay, low vacume will also cause this issue...

 

yeah my truck does that too but havent really looked for the problem. but its does it some days then other days its fine.

 

solved

Problem solved. I turned down the black knob on the throttle-body(the two ac vacuum lines lead to it) and that solved problem. Thanks to Nook for suggesting remedy!!!!!

 

can i see a pic of the knob you are referring to? please?

 

Glad you got the problem fixed.

 

Sorry, I don't know how to send pictures. Knob is on passenger side of throttlebody,located between the E and F embossed in cover. Slotted ,black hexagon with spring on shaft. Hope this helps......