2.4l quad4 vac leak, rough idle - Maintenance and Repair Forum

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2.4l quad4 vac leak, rough idle
Friday, August 21, 2020 7:34 AM
I bought a 2001 grand am with the 2.4l twin cam engine. When I bought it the previous owner said the idle was high so I figured the throttle body was dirty. I cleaned the throttle body , changed the throttle position sensor, changed the idle air control valve yet for some reason it has a rough idle.
Sitting with the AC off it will will idle fine and idles at 600rpms. But once the ac is on and sitting there in Drive it idles at 600ish rpms but idles rough. Dash and steering wheel shake. I have bumped up the idle to 800-1000 and it runs fine. I used carb cleaner to find vac leaks and the engine chokes when I spray at the top of the j take manifold flange that bolts to the block. If I spray at the bottom of the flange nothing happens. So Iím assuming I need to replace the intake manifold gasket. Would a leak at the cam tower covers cause a bad idle?

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