The 2000 LeSabre that I owned (until just recently) was passed to my 18yo nephew. It'* currently sitting in a parking lot and won't go anywhere, at least not for long. The engine will start, idles rough, and is sputtering to a stop when trying to accelerate. My brother-in-law (nephew'* dad) got it going down the road once, and it died when slowing down for a stop sign. There is no current SES light, although the light has come and gone intermittently in the last couple weeks. Scantool shows an old EGR code, but nothing current.

Any ideas? I was thinking of a possible EGR valve (but would that cause engine dying?) or clogged MAF sensor. The LeSabre has the 3800-II (naturally aspirated) and around 168k miles, and is/was a very reliable vehicle otherwise. I'm posting this second-hand, but can pass on any suggestions... Thanks in advance.

Unplug the MAF sensor and see how it runs/drives. This will throw a CEL, but is a good test for the sensor.

Just as an update, my BIL swapped out the EGR valve with no change. Then the MAF sensor, and that took care of the problem for about a week. Now, the issue returned of the engine stalling at stops or not starting (cranking, just no firing) after its been sitting awhile at school or work.

Anything else that can be tested or tried?

Had what I thought was a MAF issue, bought a replacement, had some improvement I thought, ended up being a fuel filter. Issue with older GMs, replacing the fuel filter can be very tough because of rust, replace fuel filter at huge risk fuel lines will collapse.

Hi it'* me, nephew.

I suppose I'll start from the beginning. After getting the car past state inspections (literally driving home from the place), I noticed that the SES light was on. My dad ran a scan and got code P1404 related to the EGR valve. I looked up the code specifically and it indicated that the EGR valve was stuck opened. However, we didn't do anything about it because the light turned off by itself and never came back. At this time, the car was starting and running just fine.

A few weeks later, I was in a Wal-Mart parking lot about 25 miles from home and the car wouldn't start. The engine would crank, but the car was stumbling and couldn't reach an idle. My dad managed to get it to catch my revving the engine several times so that it wouldn't die and the idle eventually caught on and he was able to drive it home.

First thing to come to mind was the EGR fault code. I read up on it and the symptoms seemed to line up very well with what was happening: rough idling at low speeds/stopped and engine stalling on start up, with symptoms more pronounced on a hot engine than a cold engine. However, the SES light was not coming on like it had before. Regardless, we decided to clean the valve. We scraped the carbon deposits off the inside, sprayed cleaner into the holes, and scrubbed/scraped a lot of junk out of it, even pushing the pintle back and cleaning the usually concealed edges. We also replaced the gasket with a new one. However, the car continued to have the same problems. I bought a used EGR valve from a junkyard for $10 hoping for some sort of change but I didn't notice any difference. From there, we decided that it likely wasn't the issue.

After that, we decided to test various sensors by seeing how the car runs with each one disconnected. We tried the MAF sensor unplugged and the car started right up. As soon as my dad plugged it back in, the car immediately bucked around and died. I bought a new MAF sensor for $33 or so from Amazon and there seemed to be a lot of improvement (including perfect startups on a cold engine, which still remains the case now), but the car still wasn't starting reliably on a hot engine.

A couple of days ago, I was driving the car along a rather busy road. I came to a stoplight in front of a school that was red and began to slow down to stop. Three cars were in front of me already stopped as I decelerated. I noticed the red battery light come on and looked down as I was braking and realized that the car had shut off and my power steering/brakes were gone. I had enough momentum to be able to sneak around some of the cars at the light to be able to stop on the shoulder. I turned the key and the car started with no problem and idled. A police officer saw me though and turned on his lights to move traffic away from me and checked if I was okay. I just told him that I'd probably pull into a nearby lot to let the car idle for a while, which I did. The car got home with no further issues.

After that incident, we decided to clean the Idle Air Control (IAC) sensor. There were a lot of black deposits all over it so we cleaned the pindle and the socket where it goes into the engine. The next day (yesterday I believe), I drove to my college campus for classes so that the engine was fully warmed up. I turned off the car and back on again. It seemed to hesitate for maybe a second but it came on and idled fine.

Then there was today. The car was driving great but the old problem came back again with losing the idle on the hot engine. I wasn't too worried about it since I can just rev it for 10 seconds or so until it catches. I got some food before going home and just decided to park the car at a local park to eat it. I left the car running so I wouldn't have to deal with starting it again. When I left, I backed out of the space I was in and started driving. I slowed down for a speed bump but the car seemed to be getting somewhat unresponsive on the throttle. I gave it more gas and it lurched forward as it clattered itself over the speed bump. I was somewhat alarmed by this and rounded a corner before pulling over on a gravel shoulder. As soon as I stopped the engine

Sounds like the crankshaft position sensor is on the way out.
You have to pull the balancer off to replace that.
You might want to get the ignition control module checked.
I think auto zone can test them.

Odd, my post sent before I was done. Nothing much else happened other than the engine dying when I stopped. I tried for 10 minutes to get the idle going and it wasn't working, so I popped the hood and turned the car off to let it cool. I managed an idle about 10 minutes later and got home.

Today, I drove the car again with no problems at all. I'm still out so something could still happen, but the engine should be cooled every time I'd ever have to run the car.

On the topic of the crankshaft sensor, is there any way that I can test it before replacing it? Will the car run with it unplugged so I can notice any difference? And for the ICM, can I just take the car to an AutoZone and they'll test it on the car or should I take it off and bring it to them?

A $33 MAF sensor? When it won't start or runs rough, disconnect it and see if it runs....

Check the vac line to the fuel pressure regulator for fuel....

Are you losing any coolant?

If you disconnect the Crank Sensor, the car will not start....

More often than not, removing the ICM and having it tested is hit or miss....

When the car won't start, that is when diagnosis is easy....check fuel pressure, spark, and injector pulse....