Rough starts on 99 SL2

99 SL2, AT, just under 130,000 miles. Recently has become difficult to start.
Engine cranks fine, sometimes fires immediately and runs perfectly, but about
80% of the time it will fire immediately and either die within seconds, or run
very rough for ten to fifteen seconds. When it dies, it's difficult to
restart. Seems to behave better when the temperature is below freezing.

Spark plugs are new, less than 1000 miles. (Problem occurred before the spark
plugs were changed.)

Any suggestions would be greatly appreciated.
TIA

 

Hi, Doug,
Sorry to hear of your problem.
Google is your friend! See
http://www.google.com/search?q=Satu...s=org.mozilla:en-US:official&client=firefox-a.
Good luck.

 

I would suspect one of two things, either 1) the crankshaft position
sensor or 2) the ignition module and attached coils. The crankshaft
position sensor is a little plastic sensor with a wire coming out of it
that inserts into the block to detect the rotational position of the
crankshaft so that the computer knows when to set off the ignition
spark. The ignition module and coils are what actually create the
spark. The position sensor costs about $40 and is easy to replace as
long as you don't mind crawling under the engine. The ignition module
and two coils (always replace them all) costs about $350 and is also
easy to replace but you probably want to try the sensor first.

 

Lots of good ideas there. Thanks much. I guess the first thing I'll have a
look at is the CTS. And I'm pretty sure I'm overdue for changing the fuel
filter, too.

 

Many thanks, Steve. The forum posts pointed me in the right direction: the
problem was the coolant temperature sensor. The existing CTS was probably
original equipment; at any rate, it had a plastic tip, which was cracked along
80% of its length. The replacement (ten bucks at PepBoys) has a brass tip.

I had one episode of rough starting, the day after changing the sensor. Other
than that, starts have been perfect for the last week and a half, and fuel
mileage is back up where it had been before the problems began.

Thanks again. Let me know if you're ever in Indianapolis; I have a cold
homebrew with your name on it...

 

Hi, Doug,
Very glad to have helped! A brew for pointing you to Google is hardly
merited but I appreciate the offer (and, as it happens, I do get to the
Indi area from time to time as I live near Detroit and my mom lives in Terre
Haute)!

 

Well, I *had* Googled, and came up empty. You pointed me at the Saturn
forums, and that's where I found the answer. The offer of a brew still stands.
Ping me here on the group next time you're planning to come through Indy.