1999 Buick Lesabre Stalling and reving up

BOWMAN

MEMBER
1999 BUICK LESABRE
6 CYL
FWD
AUTOMATIC
200,000 MILES

I have a 1999 Buick LeSabre that starts cold pretty well but stalls when driving and sometimes throttles up in short bursts. When it stalls it may take 5 to 30 minutes to restart ( not all the time but alot). It very rarely does it when it is somewhat cool out (below 60 degrees). I have a check engine light and the code is p0440 Evap issue. I am not sure why this would have any relation to my issue but it must since it is the only code. Please let me know what if any issues that could cause such code that might relate to my stalling problem. Thanks in advance for your help!

4 Replies

WRENCHTECH

MECHANIC
20,757 POSTS

You're going to have to tackle this thing during the 5 to 30 minute period where it won't start.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

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Saturday, August 13th, 2011 AT 10:52 PM

UNDUMBYOUNG

MEMBER
4 POSTS

You can also just try removing your idle air control valve and cleaning it with carb and choke cleaner. This will leave it dry, so a mist of light lubricant may be a good idea after cleaning and before reinstalling. If the idle air control valve is dirty, it can cause either too much, or too little air to enter the intake without the mass airflow sensor "knowing". This means that it will alter the fuel to air ratio and cause the engine to stall or rev. It costs nothing but time and the cost of a can of carb cleaner, so cleaning the idle air control valve is a good starting ppint.

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Monday, September 19th, 2011 AT 7:27 PM

WRENCHTECH

MECHANIC
20,757 POSTS

It's pointless to remove and clean the IAC in this engine. It's a stepper motor so all you can clean is the pintle tip anyway. This car will not restart so there is no way an IAC can cause tha.

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Monday, September 19th, 2011 AT 7:34 PM

UNDUMBYOUNG

MEMBER
4 POSTS

Well it may have been a coincidence, but when my bonneville had the same symptoms, they stopped for a considerable amount of time when I cleaned the IAC. I have seen a lot of forum questions describing the same symptoms and one person said theirs acted the worst in the rain. That leads me to think of bad electrical connections. When my bonne finally stalled for the last time, we noticed that when the key was cycled, everything on the same relay panel as the fuel pump relay would power down. The power seats and windows caused the same reaction when we tried to use them. Maybe all of this is due to a poor connection somewhere in a lot of cars equipped with the 3.8.

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Tuesday, September 20th, 2011 AT 2:31 PM