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99 Century sputters, stalls
04-16-2012, 10:06 PM
Post: #1
99 Century sputters, stalls
We have a '99 Buick Century w/3.1L V6 and 97,000 miles. Car occassionally sputters and runs very rough.

Had it to a local mechanic who changed plugs and wires.

He also swapped spark module w/another.

No change in performance.

He drove around w/computer reader and fuel pressure guage attached.

No computer codes appeared to indicate any malfunction; fuel pressure remains constant around 44 lbs.

Shortly after a sputter event, he shut it off for a few moments, then restarted it and drove away with no problems.

He then returned to garage, put it up on the lift and noticed the exhaust was red-hot PAST the catalyctic converter. He ruled out a physical blockage as this happens so infrequently.

He suggested replacing the computer but that's an educated guess at best.
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04-16-2012, 10:22 PM
Post: #2
RE: 99 Century sputters, stalls
If the gauge is correct then 44 psi is too low and you likely are running lean. (lean misfire) I'd try a new fuel filter and go for another ride with the gauge on it before condeming the fuel pump. It does seem a bit early for a pump issue as most last well over 125 k miles.... and usually closer to 150 k miles.

On the glowing exhaust, hard to say. My gut feeling is it's being caused by the poor running condition. The cat converter may or may not be damaged at this point. In some cases the core of the cat may be starting to break up and that can cause an intermittent blockage, which will in turn cause a running problem. About the only way to be positive on that diagnosis is to split the exhaust system and take a look inside. What I can say for sure is if it continues to run bad the cat will eventually be damaged.

As for setting a code in the ECM, that wont happen unless the problem exists for 5 - 10 seconds straight. Forgetting the exact code but for fuel issues it usually comes up as a multiple cylinder misfire.
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