01 Cavalier intermittent start hesitation

[BudMcGregor]

Only 115K miles and already a problem!
Every now and then, when I start , the engine will either hesitate as though I had a low battery or will both hesitate and sometimes buck or backfire. I hoped it was the battery but I had it checked at the parts store and all parts of the starting and charging systems checked OK.
I recently had another problem which may have been an indication of what was to come (and is now happening) when it threw the serpentine belt for no apparent reason. At the time I just assumed it was a fluke and I replaced the belt and have had no further problems with it but I wonder if the belt was thrown as a result of a hiccup caused by timing.
The car runs well once it starts and, so far, it has never failed to start but, if anyone can suggest some tests that will help me to understand and diagnose this problem I will certainly appreciate it. I drive 50 miles each way to work and breakdowns are a real pain.
I don't know if this is significant but I believe that the car may have been a 'flood car' because of a strong mildew or mold odor that it had when I first got it in May of '07.
Thanks.

[J-Ri]

The start hesitation sounds like probably a point of high resistance. The solenoid in my '04 went bad, and would sometimes (maybe one in twenty times) hesitate a bit on hot restarts. It could also be in the cable and/or a connection. Not too sure on the backfire, but maybe the engine just isn't turning fast enough to take off as it should... if it's running good, I wouldn't consider the backfire as a symptom unless it continues after the slow crank is resolved.

The timing wouldn't affect the serpentine belt, and it would be running bad if it was off. Sometimes water on the belt will cause it to slip off a smooth pulley, although I havn't seen that in a cavalier.

[BudMcGregor]

Thanks for the input, J-Ri.
Several years ago I had a somewhat similar problem with another Cavalier. (I've been driving Cavaliers for about 23 years.) It was an '88 wagon w/ a standard tranny and it developed a start hesitation. At the time the mileage was great but it started "funny". I'm no mechanic so I can't describe it better. After tinkering with a lot of stuff I decided to check the plugs and found the gap to be way big. New plugs made most of the problem go away. I put 267,000 miles on that car before it was forcibly retired at the hands (bumper?) of a pickup that rear-ended me.
So, tonight I put plugs in my car and now, for the next few weeks, I'll wait for the start hesitation to find out whether I fixed it or not. It DOES sound like it's starting better but I'll wait and hope it's not something more serious.
It still worries me that the belt just came off, though. (BTW, it WAS raining when it came off)
I have a theory (with nothing to really base it on) that the plugs having too large a gap can mess with the timing 'cause the voltage may a bit longer to reach a level that can generate an arc to fire.

[J-Ri]

Originally Posted by BudMcGregor

It still worries me that the belt just came off, though. (BTW, it WAS raining when it came off)
I have a theory (with nothing to really base it on) that the plugs having too large a gap can mess with the timing 'cause the voltage may a bit longer to reach a level that can generate an arc to fire.

Look at the tensioner. close one eye and line the other up with the outside edge of the belt at two points with the tensioner between where you're looking at the edges of the belt... was that confusing enough? As tensioners wear, they twist a bit sideways which moves the belt outward. You can usually let them go until you can see 1 rib outside the line the belt on fixed pulleys make. I would personally replace it if it's out at all.

[Jeffrv]

I have a similar problem surfacing in my 02 Cav, with 2.2 OHV. More often happens on first cold atrt of the day, even more noticeable in colder weather, sometimes it feels like the starter "freezes", then continues cranking. Of late, it is sometimes accompanied by what sounds like a backfire, yet itt starts. It is almost like either the ignition timing is advanced too much on start, or a hydraulic lock. Has anyone else experioenced problems like this? Are the crank and cam sensors reliable on this unit ( earlier 3800 engines have problems with these components on other GM products) ?
Any thoughts, please and thank you
Jeff

[Bud McGregor]

Thanks again, J-Ri. I'll check the tensioner. A friend made a similar suggestion. About the occasional hesitation: still happening, even though it has improved greatly since the plugs and wires are new it still does it occasionally. I'll keep looking.