Yes.
( no ) The 1.9 liter four cylinder engine in a 1999 Saturn S series has a timing CHAIN
The S series Saturn does not use a timing belt; all four cylinder Saturn's use a timing chain.
Never. The Saturn S series vehicles used a timing chain instead of a timing belt. And the chain is inside the engine, bathed in oil to keep it lubricated. The timing chain should be replaced whenever you rebuild the engine.
The SC2 is an 'S' series Saturn, and all 4 cylinder engines of the S series Saturn's used a timing CHAIN rather than a timing belt.
A timing chain, that needs to be replaced, can cause your engine to run rough and lose power. A broken timing chain can cause significant engine damage.
On a 2005 Saturn Vue : The 2.2 liter four cylinder engine has a timing CHAIN , and the 3.5 liter V6 engine has a timing BELT
The V6 L series engine uses a timing belt, which must be replaced every 100,000 miles. The 4 cylinder Saturn engines use a timing chain that typically does not need replacement until you have a reason to remove the cylinder head.
The first model year for the Saturn Ion was 2003. It uses a GM Ecotec engine that has a chain cam drive just like the original S series Saturns produced until 2002.
Early Saturn VUE's use a Opel designed V6 engine. This engine is also used in the Cadillac Catera, Saturn L series, and Saab vehicles. This engine does use a rubber timing belt that does have to be replaced every 90-100k miles. It should be noted this engine requires some very special tools to replace the timing belt. Pretty $$ tools. The tools can be rented here for 30 days: http://www.ledfix.com/timingbelttoolrental.html
Timing is controlled by the PCM .
The timing on a Saturn engine is fixed - you must line up the TDC marks when you change timing chains. Any variations in spark timing are controlled by the computer.
2002 L-series used a belt.