Rough starts on 99 SL2

Hi, Doug, Sorry to hear of your problem. Google is your friend! :) See

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.

Doug Miller wrote:

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

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.