I assume you have the 2.4L.
Did you set the timing right?
Here is how you do it:
Set crankshaft sprocket to TDC by aligning the sprocket with the arrow on the oil pump housing. Then, set camshafts timing marks so that the exhaust camshaft sprocket is a 1/2 notch below the intake camshaft sprocket.
Install timing belt. Starting at the crankshaft, go around the water pump sprocket, idler pulley, camshaft sprockets and then around the tensioner.
Move the exhaust camshaft sprocket counterclockwise to align marks and take up belt slack.
Insert a 6 mm Allen wrench into the hexagon opening located on the top plate of the belt tensioner pulley.
Rotate the top plate COUNTERCLOCKWISE. The tensioner pulley will move against the
belt and the tensioner setting notch will eventually start to move clockwise.
Watching the movement of the setting notch, continue rotating the top plate counterclockwise until the setting notch is aligned with the spring tang. Using the allen wrench to prevent the top plate from moving, torque the tensioner lock nut to 30 N·m (22 ft. lbs.).
Setting notch and spring tang should remain aligned after lock nut is torqued.
Remove allen wrench and torque wrench.
NOTE: Repositioning the crankshaft to the TDC
position must be done only during the CLOCKWISE
rotation movement. If TDC is missed, rotate a further
two revolutions until TDC is achieved. DO NOT
rotate crankshaft counterclockwise as this will
make verification of proper tensioner setting impossible.
Once the timing belt has been installed and
tensioner adjusted, rotate the crankshaft CLOCKWISE
two complete revolutions manually for seating
of the belt, until the crankshaft is repositioned at the
TDC position. Verify that the camshaft and crankshaft
timing marks are in proper position.
Check if the spring tang is within the tolerance
window. If the spring tang is within the
tolerance window, the installation process is complete
and nothing further is required.
