Buick LeSabre engine cutoff

My 2002 Buick LeSabre has an intermittent engine problem. It starts and runs fine then after a few hundred yards, when I step on the gas a little harder, the engine cuts off ad on as if I were turning the key off and on. Everything else is normal, that is, lights and accessories remain on. OnStar tried to check it and had no answer. I took it to a shop and had an OBD check for codes. Nothing.
The weather is cool and I thought maybe something iced up the first time it happened. I found a sensor connection that was loose. (TPS I think??) Car ran fine for several days. It happened again under the same conditions and I pulled off the street and just shut down and restarted and drove on as if nothing was amiss.
Does anyone have any ideas? Tester? How about you?

Bad or dying ignition switch, perhaps?

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Could be the crankshaft position sensor beginning to go south.

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or MAF sensor. my similar aged grand prix did that. died on roadside and would not start. unplugged maf and it ran ok. got home, plugged it in and it ran fine. i think it happened again so i got a new maf. they are cheap


an intermittent problem is always the worst kind . , I dont know if you can leave a hand held code reader on all the time when your driving so when it does happen the code reader would detect the fault? hmm

You’re probably going to have to do some more work, the objective being to determine what things make this more likely to occur, & what doesn’t. Especially good if you can figure a way where it will always happens. Try various things, brakes on/off, headlights on/ff, AC on/off, different speeds, transmission in gear 1/2/3/4, coasting vs in-gear, slowing vs speeding up, etc. Does this only happen at idle, or does it never happen at idle? There’s so many possibilities that more clues are needed first.

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I had a similar problem with a 1998 Olds Intrigue. It stopped when I removed the short ground cable that went to a 10 mm bolt right under the battery that was corroding from battery fumes and replaced it with a longer ground cable to a bolt on the engine.

I’m pretty sure this model uses a junction terminal so you might consider checking and cleaning that. All electrical power for the other than the starter motor windings goes through that terminal.

There should be a short lead from the battery positive terminal going to a stud under a small plastic cover. Raise the cover, remove the nut, and clean all wire ends. It’s cheap and easy. It should be located near the battery.

Problems with this terminal can cause intermittent no-starts or random dying. Hope that helps.


It’s only happened a couple of times. The first time I called OnStar while it was happening. There was no indication of trouble according to them. I also had a reading done with OBD . No problems there either. So whatever it is, it’s not within the diagnostic range. Must be a physical problem somewhere underhood.
Everything else stays on. Lights, radio, phone, gauges, etc. It happens after I drive away from the initial start. cold. About 400 or so yards, then the problem starts when I apply throttle to get up to local traffic. 35 -40 MPH. It continues until I back off the gas. If I stop and Shut the engine off and restart it, the problem goes away.
In response to your list… Brakes not related, Headlights are automatic, A/C off.That’s automatic too. Panel control is on vent. Trans in any gear, including park.speeding up starts it. Never at idle. The MAF is new, about a year or so. The car has about 52 K miles.
Ledhead suggested a bad ign. switch. But wouldn’t that also cause accessory power cutoff?
Any other ideas? My biggest query is why does the problem go away after a restart? You’d think it would linger.

The battery is under the back seat in this model. I have no idea where the junction terminal is. On the starter, maybe?
It’s more like the Rev limiter is actuating when you floor the gas in neutral.

The battery is under the rear seat.
Good thought though. Thanks.

Low mileage. 50 K No other systems are affected when this happens though.
Thanks for the thought. It’s not ruled out yet, though.

MAF and MAP are OK. MAF is new.

Wouldn’t that be in range of either it works or it doesn’t? Go or no go?
Not ruled out though. Thanks.

Is the REV limiter built into the main computer or is it a mechanical device attached to the engine ignition system?

I’m afraid that I don’t know where the junction terminal is on models with the battery under the seat. Maybe someone else can chime in on this. None of my books show it but as far as I know all Buicks, GMCs, Chevys, Oldsmobiles, and even SAABs use a junction terminal.

When a problem develops with scale or corrosion the car may suddenly not start or randomly die.

Many years ago while on vacation in CO I checked into a hotel. I came back out and the SAAB was stone dead with nothing working including the starter motor. I loosened the nut on the junction terminal, wiggled the leads around, retightened the nut, and all was fine until I got a chance to clean it properly.

If I had that problem I’d connect a volt meter in the passenger compartment to the B+ terminal of the ignition module and watch to see if the voltage changed when this happened. If that turned out ok, next I’d connect a fuel pressure meter to the fuel rail and tape it somewhere I could see it while driving, looking to see if the fuel pressure changed just before this problem occurred. It’s going to be hard to fix until you can narrow it down to either spark or fuel.

Get a wiring diagram for your car. Haynes manuals aren’t good for much, but the do have wiring diagrams near the back of the book. Maybe you can find the junction terminal on it. @ok4450, is this the junction with the fuse boss, or somewhere else? If we are cleaning terminals, I’d start under the hood and leave the electrical connections under the back seat for last. My father in law had a starting problem with his mid-2000s LeSabre, and I looked at the battery. It looked like it had just left the factory after 12 years. If you don’t ave diagrams, check the public library. They often have auto repair manuals. You can check it out or photocopy the pages you want.

That’s a good idea. But somehow I don’t think the battery is involved since no other system shows any problem.
I’m starting to think about the rev limiter. But I’m not sure what makes it operate. Engine Sensor?
And why does a simple restart make it go away?
Could the TPS be sticking intermittently?