'97, intermittent stalling, MAP sensor code

[dkellyu]

I read through lots of messages about similar problems, but haven't seen anything about MAP sensors yet, so...

My 1997 Buick LeSabre with just over 100k miles is stalling intermittently, without warning. It restarts immediately in neutral or park. It hasn't happened at faster than 45 mph or so. It usually (perhaps always?) happens while I'm slowing down.

It was misfiring and sputtering a while back, but a new fuel filter and related fuel system maintence took care of that. It has run beautifully since then, although the check engine light was still on.

When it stalled for the first time a couple of weeks ago, it stalled four times within about 20 minutes. A day or two later, it idled in park for two hours without a problem. Then, while driving, it stalled again about 10 minutes into a 40-minute round trip, but was fine the rest of the way.

It was in for repairs last week. The fuel pump motor and lines (tank pressure side and return, I think the receipt says?) were replaced. The mechanic said the fuel pressure was at 20 something before the repair, and at 40 something afterwards. Before the repair, it had the following trouble codes:

P0102 mass (?) air flow circuit low
P0107 MAP or baro (?) pressure signal low
P0171 fuel system too lean, bank #1
P0300 random misfires detected
P1107 MAP sensor (illegible) intermittent low

Since the repair, the only code that doesn't clear is P1107, for the MAP sensor. The check engine light is still on. The mechanic test-drove at length without a stall, before and after the repairs.

He said the MAP sensor was the next thing that should be checked, but that it's not "critical" and a problem there wouldn't leave me stranded. I told him I was headed directly from the shop to Philadelphia, 90 miles away, and he didn't bat an eye. Well, I stalled five times on the way there -- four times on highways (going 45 or slower in heavy traffic) and once in town. Yet I stopped at more than a dozen lights in town with no stalling.

The car sat for about half an hour before the 90 mile return trip home. There were no stalls for that, although I saw the oil pressure gauge start to nosedive when I slowed down near a tunnel entrance (from 65 mph to 45ish). I gunned it a little, maintained a 50 mph speed in the tunnel, and it was fine after that, even through the final 20 miles of mostly 45 mph speeds.

Does it sound like the MAP sensor really is the likely culprit? What are the other possibilities? In what order should they be investigated? Any insight would be greatly appreciated.

Thanks very much in advance!!

[taillight]

I really sounds like the MAP sensor. I would replace it with a new GM sensor.

[2001jettavr6]

i agree get you a new MAP sensor its 44.99 at autozone. Then id recommend to change the wires and spark plugs.

[jerryls]

Please let me know what the problem is if you actually solve it. I have the same problem with my 94, I changed the computer thinking for sure that was the problem, but it wasn't. Still dies while decelerating at slow speeds. I hope it is the MAP sensor, but I've read many times before that people are pretty sure about their suggestions, but then readers try it and it still stalls. I'm anxious to hear as I don't want to waste any more money by trial and error.

[dkellyu]

Originally Posted by 2001jettavr6

i agree get you a new MAP sensor its 44.99 at autozone. Then id recommend to change the wires and spark plugs.

Thanks to you and Taillight. If we can get away with just $45 more, I'd be thrilled. My husband changed all the plugs/wires when he did the fuel filter and whatever else. He's actually a heavy-duty truck mechanic but doesn't know a lot about cars with computers. The computer is #2 on his list of possibilities.

Jerryls, I will let you know how we solve the problem, assuming we do. It's incredibly frustrating.

[jerryls]

I wouldn't consider the ECM computer second on your list. As I said previously, I have the exact same problem, changed the computer and still I have the same problem.
Jerryls

[dkellyu]

Originally Posted by jerryls

I wouldn't consider the ECM computer second on your list. As I said previously, I have the exact same problem, changed the computer and still I have the same problem.
Jerryls

OK, I'll pass that along to my husband, thanks. He's going to order the sensor today.

[dkellyu]

Update:

It wasn't the MAP sensor. The check engine light stayed on after the sensor was replaced, and it stalled under same conditions as before.

DH took out the EGR valve yesterday, and it was sticking. He cleaned it, replaced the gasket, disconnected the battery overnight to clear the computer, and then went for a ride. It took a little while for the check engine light to come back on, but it did come back. The car didn't stall, but he wasn't out for too long.

I read in a response to another post that the idle oxygen sensor (?) is another possibility? Does that sound right? What/where is it?

Thanks again!

[formzy]

Although the code doesn't sound like it comes up, my girlfriend's '97 leSabre had the same stalling problem and it turned out to be the Crankshaft position sensor. I pulled the code on hers that was in memory. It's basically a magnet that senses spark pulses etc. and it gets weak and overheats. I've heard some fellows pouring water on it to cool and restart the engine.

We had hers replaced (150.00) parts and labor about two years ago and no problem since. Before you look at the o2 senser I would check this out.
It is located on the right side of the engine bolted against the harmonic balancer. You'll see a wire conector that goes to it.

Good Luck!

[HotZ28]

Originally Posted by dkellyu

Update:

I read in a response to another post that the idle oxygen sensor (?) is another possibility? Does that sound right? What/where is it?

Thanks again!

It is best to start from fresh and clear any old, or erroneous codes, then see what comes back. BTW, you must be referring to the idle air control (IAC), not the “idle oxygen sensor”.

[jerryls]

[quote=dkellyu]Update:

It wasn't the MAP sensor. The check engine light stayed on after the sensor was replaced, and it stalled under same conditions as before.

Thanks Dkellyu! Now I can save the $45.00 for the MAP sensor. FYI, i cleaned my PCV valve and changed the Oxygen sensor about a year ago. I still have the intermittent stalling problem. Another problem I have and I'm not sure if it's related to the stalling while decelerating is that sometimes the engine idles very high when cold.
Curious to know what finally solves the problem?

[dkellyu]

At the risk of jinxing myself... Please cross your fingers before reading further, just in case...

The car might be fixed. After the light came back on following the new EGR valve, I had it checked again for trouble codes. This time the code was for the MAF sensor (mass air flow).

By this time, we were pretty sure there were two problems: one causing the intermittent stalls that came on without warning (because that started while the car was running fine), and one causing the car to run rough, idle unevenly, etc. It seems likely that the bad EGR valve was the cause of the stalling. It seems certain that the MAF sensor was the cause of the rough idle.

The new MAF sensor went in yesterday, and it's running beautifully, without stalling so far, and without the check engine light coming back on. I drove for about an hour in stop and go traffic in town, at 65 on the interstate, made some stops, screeched around a couple of turns and stopped short all the way up our long driveway... Everything I could think of to encourage a stall while decelerating and/or rattle a possibly loose wire to make the light come back on. Nothing!

My husband is starting to think the car was struck by lightening because of all the electric stuff failing at the same time. Everything that has been replaced was a shot in the dark with regard to the stalling, but it all needed to be replaced.

Oh, one thing he realized yesterday that someone might find helpful: it can take a minimum of four hours for the codes to clear from the computer after the battery has been disconnected.

[jerryls]

That's great that the MAF sensor fixed the problem. I see it was a code that came up in your original post. I think maybe the EGR valve caused the rough idling and the MAF sensor the stalling, but either way i'm glad to hear it solved the problems. I have to now find a MAF sensor that is inexpensive, maybe from a junk dealer, The MAF sensors on line are $120 or so. I imagine the same one is used on multiple GM vehicles? Does anyone know? My 94 has over 170K miles and is not worth putting a lot of money into it.

[HotZ28]

Originally Posted by jerryls

I imagine the same one is used on multiple GM vehicles? Does anyone know?

According to the Cardone MAF part number for the 94 LeSabre, it does show quite a few other GM cars listed with the same number. Click Here FMI

[jerryls]

Thanks HotZ28- I'll see if I can find one