I installed a throttle body from a 2.4 LE5 on a 2009 Pontiac G5 2.2 LAP. The install was a direct replacement and the throttle was noticably larger.
I unplugged the battery neg on the battery and did the install. They are both 6 pin. The engine runs without a cel code in with the newer throttle body. The problem is the idle speed is really high, like at 4000k. I tried draining the capicators by keeping the ignition in the on position with the battery unplugged, it didn't work. The same thing happens, like the throttle is stuck open. When I put the original back on, the problem went away.
I've read on here that other members have had luck with this same install so I'm wondering what the issue could be. Maybe the computer needs to relearn the idle position but having it idle at 4000rpms is a little unnerving. I believe I can make this mod work somehow. Anyone with experience with this have any advice to offer?

 

You need a tune for the throttle body. You can swap the intake manifold with no tune though.

 

The probable is the engine is bringing in more air than the smaller TB and the ECU must be retuned to regulate the extra air flow! Once the car is tuned it will run fine again and you will feel improved throttle response from the larger TB you have installed. Good luck.