1997 Saturn SC1 Timing my Saturn

DAVID MARSHALL

MEMBER
1997 SATURN SC1
4 CYL
2WD
AUTOMATIC
152,000 MILES

I need advice on how to time my DOHC fuel injected Saturn motor. It is a 1.9L 4 cylander. I am unfamiliar with the timing techniques on these kinds of motors. I have timed a V8 motor with a regular distributor cap, but the one on the Saturn is square and it has made me think twice before diving into it. I have changed the oil, oil filter, air filter, spark plugs with the correct gap and flushed the radiator. I need to time the car now, it runs really rough when it is in gear at stop signs and it seems to run rough when just driving normally.

Please Help!

Thanks,
Dave Marshall

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Hi David Marshall and welcome to 2carpros

Ignition timing is not adjustable its electronically controlled by the computer

it runs really rough when it is in gear at stop signs and it seems to run rough when just driving normally.

A rough idle could be caused by vacuum leak- can lean the air/fuel mixture out to such an extent that an engine will not idle at all. An EGR valve that is stuck open at idle can have the same effect as a vacuum leak. So too can a loose positive crankcase ventilation (PCV) hose, a leaky PCV valve or the wrong PCV valve (one that flows too much air for the application). If somebody replaced the PCV valve recently, they may have installed the wrong PCV valve. The rough idle in all of these cases is caused by "lean misfire." The fuel mixture is too lean to ignite reliably so it often misfires and fails to ignite at all. Lean misfire will show up as elevated hydrocarbon (HC) readings in the exhaust, which may be enough to cause a vehicle to fail an emissions test.