02' engine light comes on after 50km
 

My 2002 SL 5-spd sedan runs really smooth for about 50km, then it stumbles on light throttle acceleration and the check engine light comes on.
Each time this happens, I remove the negative battery cable for a minute or so, the check engine light goes off and car runs nice and smooth again...for about 50km. I have done this about 3 times now in the past ten days.
My instincts tell me it is a bad plug wire (and it has been damp and rainy lately), so I checked the plug wires for visible problems, made sure the plug wires were all well separated, sprayed a bit of wd40 inside boots at both ends, inspected the spark plugs and checked gap, and for good measure unplugged, wd40, and re-plugged every other electrical connection under the hood. The car ran smooth again...for about 50km. So I accomplished nothing.
From what I have read there is no way to read the engine code by light flashes on 2002 Saturns? Before I go borrow a code reader, is there anything else from your experience I might be missing that could cause the stumbling on light acceleration problem to keep recurring about 50km after the computer is reset?
Thanks!

Sounds like whatever the code is it is throwing the car into limp mode.

Go get the codes read at autozone or similar. It's free. Get and post the codes (Pxxx) not the descriptions and we will try to help you out.

Will do, thanks. But I'll have to wait until it throws the engine light on again, which should be pretty soon...I unhooked the battery about 30km ago, so today or tomorrow the code should reappear. Or maybe I will get lucky and it won't...
dan

It may already have the code stored as a "pending" code" (will come up on a scanner with a small "p" or "pd" next to i. So you can get it read both ways but definitely read with the light on, since you don't know if that pending code, if there, is the one that ultimately sets the light (I've seen stranger things).

I think I might have found the problem. The gas tank neck had some corrosion around the sealing lip. I cleaned up the rust, cleaned up the gasket and put a smear of silicone grease on the gas cap seal, and so far so good...no check engine light in 70+km. If/when the light comes back on I will borrow a scanner and see what it says...but with luck the gas cap not sealing properly was the problem. Fingers x'd for luck!

The hard part to deal with on a computer controlled engine is that they are incredibly complex when it comes to how and why they operate. Thus when they have some form of a failure mode it becomes a wildly guessing contest as to what might be a problem that is actually causing what ever symptom is taking place. It is next to impossible to "guess" what something might be with information that has been given on this problem. What is important to know is what if any error codes are given when read. Many error codes are saved and can be read at any time, others must be read when a check engine light comes up.
It also helps to purchase a mitchels or what ever service manual for your car which gives a lot of information, specially information on how to interpret the error codes when seen can save a lot of stress and frustration when trying to figure things out.
The help section of the autoparts store generally has them.
See if you can get the codes read out to further add information to te data obtained.