Engine - Rough Idle

SOURCE: Kia Technician Times

TITLE: Rough Idle

APPLIES TO: Optima 4-cylinder

SERVICE TIP:

Complaints of rough idle in 4 cylinder Optimas may be caused by incorrect cam timing. A quick check for incorrect cam timing is to use a vacuum gauge to check engine vacuum at idle. Normal vacuum should be 19-21" Hg. If vacuum is less than this and is unsteady, check cam timing as follows:






1. Rotate engine to #1 TDC timing mark at crankshaft pulley.
2. Remove upper timing belt cover.






3. Inspect position of timing marks on intake and exhaust camshaft pulleys. The marks must line up with corresponding marks on rocker cover.

If timing marks are not aligned, cam timing must be reset. To correct incidence of timing belt jumping in Optima 4 cylinder engines, a belt guide has been added to the inside of the upper timing belt cover from 1/29/01 production.