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I've got a 1999 Saab 9-3 2.0l Automatic (not the turbo).

It's been running fine, then a bit more than a month ago it started to stutter when accelerating or decelerating. Only occasionally, but it would feel like the car was about to stall, or it would lag a bit then lurch forward.

When this WASN'T happening, I'd sometimes get the CHECK ENGINE light coming on, but that would never stay on for long and by the time I got it home and plugged in a fault code reader I'd just get "no codes".

Finally, today I was doing 30 and the car just cut out. I was on pretty flat land with barely any gas, and it just died. I pulled over to the side of the road, turned off the ignition, waited a minute and started it up again. I drove home fine with no stuttering, cutting out or engine light.

The air filter looks fine, the spark plugs are a bit sooty but they are clear where the spark is. The oil and transmission fluid is clear and there's no gunge or dirt around the filler cap.

Any ideas where I can look or how I can diagnose anything more certain?

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closed as primarily opinion-based by Bob Cross Jul 22 '13 at 12:10

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

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When was the fuel filter last changed? –  Timo Geusch Aug 14 '12 at 1:27
    
Before I had the car. Only had it 5 months ago. I've got a new one on order as it looks pretty easy to change. But I have let the tank get pretty empty a few times, so I might have filled the lines and filter with rubbish from the bottom of the tank –  Willshaw Media Aug 14 '12 at 5:55
    
Changed the filter, car seems to be running better since. Not sure if it was the new filter, the fact I pretty much drained all the fuel out when doing it due to a naff washer, or the reseating of the spark plugs and leads I did before touching the filter. –  Willshaw Media Sep 7 '12 at 8:45
    
As the car is now scrapped I can't really resolve this question, but the suggestions might make this question useful for someone else. Can someone close the question for me? –  Willshaw Media Jul 22 '13 at 11:10
    
@WillshawMedia: Sure - I'll close it for you. Thanks for following up. –  Bob Cross Jul 22 '13 at 12:09
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2 Answers 2

It is possible that you have a secondary ignition issue. You may be able to isolate it by waiting until dark and start the engine. With the hood open look around the engine in the area of the sparkplugs and plug wires. You may see some arching as individual plugs fire. This is a sign of bad wires or other ignition components. If nothing is visible shut off the engine and spray a plug wire with a spray bottle of water. Restart the engine and see if it is running rough or missing. Do this to each wire and the coilpack. While this doesn't verify an ignition component as good it might point you toward a bad one.

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Not head that one before, I'll have a look this evening when it's dark –  Willshaw Media Aug 16 '12 at 12:13
    
@Skeater, it’s quite common when the wires deteriorate, and the moisture can get into the micro-cracks in the insulation. –  theUg Feb 13 '13 at 2:35
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Hopefully this is still unresolved :) It's been a few months since the last activity.

I would suspect a faulty oxygen sensor. These often be quite flaky when they start to go bad, so that you don't see consistent behavior. You often will see the stuttering you describe because the fuel/air mixture is way off. They will also sometimes trigger an engine light, but not always. Again, the behavior from a bad O2 sensor is often flaky.

Replacing oxygen sensors is usually pretty cheap as they are not expensive parts. I would suggest simply replacing them and seeing if the problem goes away.

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The car is actually scrapped now! I hadn't got any closer to diagnosing it apart from it only happened in hot weather. So given the current heat, I'm glad it's gone. –  Willshaw Media Jul 22 '13 at 11:09
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