Hi,

Posted this in another area, not sure it was the right place so reposting here.

My 1994 Buick LeSabre Custom seems to begin surging and stalling after it idles for a few minutes on hot days. Although the idle is always extremely rough, it runs OK all day but if it sits and idles for a few minutes it will begin acting up. There is no SES light; however, my mechanic was finally able to get one code, one time, which said cam/crank error 1. The Camshaft Position Sensor was replaced a few years ago. The car smells hot when this happens and the muffler makes a lot of noise. The car generally restarts quickly after stalling but idles very roughly and will not go over 25 MPH and the idle is all over the place and it doesn't want to accelerate. Giving it gas causes it to buck quite hard and is noisy until it stalls again. It will continue to run badly and stall until after cooling down over night when it is usually fine again for a while.

The coils, plugs, wires, ignition module, computer, intake manifold, intake manifold gasket, and various sensors have been replaced various times and a lot of money has been spent on it. The stalling issue has been going on for years and so far no fix. The car goes through gas quickly, especially when it begins to act up. This seems to be a hot weather issue as it was fine last winter.

Does this sound like a Crankshaft Position Sensor problem or something else? I don't know if this makes any difference or not but it seems to happen after going over speed bumps. It may just be a coincidence, so I don't want to say it always happens after that.

The car is well maintained and has 99,500 miles.

Thank you for your help.

Because it happens when the engine is hot, it could very well be. You've narrowed down the usual suspects like coils, plugs, wires, ICM, etc.

Now, when I had a failing crank sensor, my engine ran fine, aside from either stalling, or wanting to stall before finally stalling, so you may very well have multiple issues on hand.

Your inability to accelerate smoothly and your poor fuel economy could be caused by bad manifold absolute pressure (MAP) and/or mass airflow (MAF) sensors. Try unplugging your MAF sensor and seeing if things improve (just don't accelerate too hard without it). Worst case, you may have a plugged catalytic converter, which would easily explain your artificial speed limit.

Oh, and welcome to the forum! Didn't notice that this is your first post. Hope we can get you back on the road.

My guess would be, a fared or broken wire.When dark, open hood and check for spark, from wires.Look very good,my 88 bonnie did this,it was a wire in the harness, towards the fire wall... There was a faint blue light from the fared wire.Spliced,taped,she ran like a top...

I would suggest putting a real time scanner on the car. Might have a tough time finding someone with an OBD1 scanner though.
Check all the values to make sure the sensors are within spec. I had a tough time with mine until the day it refused to start. I put my scanner on it, and my MAF readings were all over the place, even without the engine running. The MAF, especially on the older cars are more prone to heat related problems, making them a prime target for hot start/warm engine problems.

My sisters 01 Regal just had the cat converter replaced. Sounds a lot like the symptoms she was having. Bad mileage, no power, couldn't get past a certain speed, etc.
Like someone else suggested, you may have multiple issues going on.

Hi,

Thank you for all the replies. I purchased and am using an auto code reader that works in real time. I have it connected to my car when driving. Everything seems to be working correctly; however, even when the car is cold the O2 Sensor readings fluctuate, should it?

It also reports an occasional Cylinder 5 Misfire.

The car idles extremely roughly but has not stalled again since I got the code reader. Gas mileage is still an issue as well.

Thank you!

I would pull the plug on cylinder 5, and check it. Also, when its dark out, run the engine and check for any arcing from the plug wire. I know on my 04, the #5 wire is really close to exhaust heat, and it might cause it to break down over a short period of time, and it might be arcing to the exhaust manifold.
The O2 should fluctuate. I'd be worried if it didn't.

I would seriously look at getting a backpressure test done. It really sounds like how my sisters 01 Regal was behaving when the cat converter was plugging up. (minus the misfire codes though). A clogged converter usually wont show any codes, especially in OBD1 cars without a post-cat sensor.

Just as a quick check, with the car in run, but without the engine running, hook up the scanner and check the following:
TPS, without foot on the gas should be 0. Put foot all the way down, should read 100
MAF, should read 0.0 g/sec airflow
IAT should read ambient air, or somewhat warmer depending on how warm the engine bay is.
Coolant temp should be within a reasonable temp

Any of the above could be within a "normal" range, but still reading incorrectly. Just not far enough off the "scale" to throw a code.

I think having the converter checked out is your best bet. And figuring out where the misfire is coming from.
With the car cold, if you can get underneath it, tap the converter with your hand and listen for any rattling inside. If you hear anything, its likely that the honeycomb structure inside has broken down and is blocking part or most of your exhaust gases from escaping. If your engine can't breathe, it will stall and run rough. Plus it will run rich as well.

I am also having a similar issue. The car starts right up runs fine for 5 to however many minutes and just dies out. The car will start up right away after this also happens. Allready narrowed out plugs, wires, coils. Ran the scanner on it and it came up with nothing. Does this also sound like a crank censor?