Buick Lesabre Stalls At Low Speed Deceleration

2000 Buick Lesabre Custom. Had the PCM scanned at my local auto parts store and no codes came up. Not sure why.

Question:
Car has 58,000 miles. It stalls on very low speed deceleration and restarts immediately. Spark test done and diagnostic scan with no codes expressed. Can the MAF, Crankshaft Positioning, Throttle Positioning sensors and or the ICM give false negatives when scanned? If not usual then what are possible other suspects. Thanks.

With no codes in the computer of your Buick LeSabre, it would be hard to diagnose over the computer. The MAF, crank position, ignition control module would not cause the problems you are having. If they were the car would not start right back up. Of the things you listed the throttle or TPS sensor is a possibility. But this will usually set a code in the computer.

If it does not feel like the transmission is jerking, sort of like a stick shift trans where you forget to press the clutch as you are slowing down, then the most common cause is something simple like carbon buildup inside the throttle. Get the throttle body cleaned real well then take an expressway drive and sort of clean it out by doing several very hard accelerations. A dirty throttle will affect your cars idle.

To answer your question about false-negative's when a computer scan, a sensor can have what is called an intermittent problem where the problem occurs so quickly that the computer does not catch it to set a code. This is not very common but I have seen it before. This makes it very hard to repair a car with this sort of condition. The mechanic would have to be driving it and experience it himself while watching live streaming data on his diagnostic computer. Many times he will be able to graph the live data, look at it later and see a glitch. But again this is not very common. Have the throttle cleaned out before you do anything.

In regards to the crankshaft position sensor, when they fail normally the engine will stall and will be very hard to start until it cools down.

And MAF sensor will usually cause poor acceleration or hesitation that acts similar to low fuel pressure. I have had a few that cause stalling but not many.
A bad ignition control module or ICM almost always will cause a car to stall and not restart. Low speed deceleration has no affect on an ignition control module.

Question:
Have 2000 Buick LeSabre 3800 engine. It will just die while in normal driving but it starts back immediately. Changed fuel pump, throttle solenoid, idle control sensor, ignition module. Nothing has helped. We even put a new gas cap on it.

Answer:
Two possibilities. A faulty crankshaft position sensor. This would cause a loss of spark and injector pulse, and usually does not set any codes. It is located behind the crankshaft pulley. Or a possible faulty ignition switch. This may explain the dash lights, since the ignition switch feeds power to many of the cars electrical systems. After a stall, the check engine light should usually come on, along with a few other lights. Try tapping on the key when engine running. This will sometimes cause a faulty ignition switch to act up.

Question:
1993 Buick Lesabre. My horn sometimes works & than not at all. .What can I look for?

Answer:
If when the horn does work, it sounds funny, not like it use to, then that indicates bad horn(s). If it seems to not work when the steering wheel is tilted up or down, or when turning the wheel, then the problem is probably in the steering column.

Either a problem with the horn pad(air bag module if it has airbags), or with the wire on the back side of the pad that attatches to the contact in the column. The horn pad(or air bag module) will have to come off.

WARNING- THE SIR SYSTEM WILL HAVE TO BE DISABLED. Could also be a problem with the cancel cam, also inside the column. Have seen any of these things cause your concern.

Question:
Buick custom lesabre 2002. Runs good, but after starting first in the morning, it takes a little longer to start with starter after that. I replaced gas cap and secured it, but still same slow start. Not real bad, but not like it used to be.

Answer:
Make sure you do a complete tune up. Check fuel pressure. Check for a leaking fuel pressure regulator (FPR). Check for a vacuum leak. The intake manifold gaskets are a common problem for that. Check for carbon buildup in the throttle.