2000 LeSabre stalling while driving, sputtering and hesitating from a stop. What is wrong?

Maintenance/Repairs
1

I have a problem in the form of a 2000 Buick LeSabre Custom with the GM 3800 series II engine. After 245k miles, it has begun to show it’s age in some very unaffectionate ways. It has been stalling, sputtering, hesitating, and unwilling to start at seemingly random intervals. And, such is my luck, there has been no ‘check engine’ light on at any point during this saga. Here’s the chronology of events spanning 6 months:

The first symptom I experienced was occasional sputtering, mainly while going uphill. This began to occur shortly after the spark plugs were replaced during regular maintenance. So I replaced the spark plugs again, and also the wires, fuel filter, and fuel pressure regulator. Plus I gave the MAF a good cleaning.

But the problem persisted, and grew to include intermittent stalling when I would come to a stop. Undaunted, I replaced the ignition coils, and swapped in a used ICM.

The car, obviously displeased with my choice words toward it, began to not start every now and then. It would just crank to no avail. So I would try again after an hour or two and it would immediately start as if nothing was wrong. Fearing that I or my wife could be left stranded I replaced the fuel pump. It continues to stall every once in a while and it still sometimes sputters at low rpms. A lot of times it just wont idle at a constant speed.

So then I replaced the crank sensor and I cleaned the camshaft sensor too. Guess what? It’s still intermittently sputtering/hesitating when I accelerate from a stop. And I have noticed that it will also sputter while idling in park as well. It’s like it’s misfiring, but with no engine codes. I’m not happy.

I think I suffer from vehicle loyalty because I probably should have put it out to pasture long ago. But as a second to last resort, I’m asking for help. Help?

Cheers,
Mike
Fort Mill, SC

2

An air leak which allows unmetered air into the engine can cause this symptom. I’d say that is the most likely. Air leaks can sometimes be difficult to find though. You need to understand what all the air paths into the engine are, and test each one for malfunction, one by one.

The other thing I was thinking reading your OP was that you may have dirty fuel injectors. What the fuel filter replacement status? If it is long overdue, one idea is to suspect clogged fuel injectors. In that case what I’d do if it were my car is replace the fuel filter, and try a dose of injector cleaner. If that seems to help, then I’d take it to a mechanic and ask for the full injector cleaning shop treatment.

3

If there were an air leak into the engine, it would cause the Check Engine light on come on with a lean condition code.

The MAF sensor monitors the amount of air that enters the engine. The oxygen sensor compares this reading and makes adjustments to the fuel delivery to the engine. If air enters the engine after the MAF sensor, the oxygen sensor will detect this extra air that the MAF sensor didn’t detect, which will cause the lean condition code.

From your description, I would first try cleaning the throttle body and the Idle Air Control valve.

Tester

4

Well after another trip to the salvage yard, I swapped in a used idle air control valve and a mass airflow sensor. I suspect that Tester is right and that the IAC was the problem. I just threw in the MAF for good measure. Now it’s right as rain. Cheers and thank you.

5

Glad you are back on the road. +1 for Tester’s great diagnosis!