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'99 LeSabre - stalling problems

aycockaycock Posts: 6
edited July 2018 in Buick
I have a 1999 Buick LaSabre that began stalling when it was hot and the outside temperature was hot. Now it stalls when cold also and the car seems to want to cut off sometimes when driving. Sometimes it will crank back up on the first cranking attempt and sometimes you must wait up to ten minutes. It will sometimes cut off when I take my foot off the accelerator and come to a stop. I have replaced the crank sensor, MAF sensor, EGR, and fuel filter. Replaced fuel pump about two years ago. I do lots of stop and go driving. What could be the problem? Thank you.

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Answers

  • aycockaycock Posts: 6
     Several codes have been corrected by satisfying the issues that were identified as causing problems. The problem of stalling continues and the only opportunity I have had for testing is after the car is back running and at that point the tester reflects no codes. Thank you for your help. Maybe we can get this issue resolved.
  • aycockaycock Posts: 6
    Thank you.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,959
    edited July 2018
    Some thoughts from owning leSabres from 02 until 2015 on what I experienced and read about on H-body forums for leSabres and Bonnevilles (and Oldsmobiles).

    Does it cut out completely and immediately when it does the stall or stumble? Or does it sort of work its way down to stalling? If you can watch the tach when it's just stalled or is feeling like it's threatening to do so, does the tach go to zero indicating no spark or timing signal from the CPS/spark control module?

    Also, I've not verified this but when it won't restart immediately and needs to cool, does the tach show rpm's indicating it's getting a signal from the CPS and spark control module. IF it shows 0 while cranking, that could verify you're losing the spark signals from the CPS or from the spark control module.

    Then I'd check the connections and wires for the CPS. Maybe a broken wire or poor connection.

    You might hook up a resistance meter to the right two of the three wires on the TPS and operate it to see if you can catch a break in the smooth increase or decrease in the resistance from a worn TPS.

    The spark control module might be failing. If you have access to a pick n pull you might get a used one to substitute for yours. If you look on Rockauto for the one fitting your car by AC Delco and click on the blue part number, it will list all the GM cars using the same part. Same for the ACDelco.com parts site. Occasionally people had problems with the connection of the leads at the spark control module. Might take them off and clean.

    The test on the ISC that they do at parts stores didn't seem to catch ones that were problematic. Since this sounds like heat soaking might aggravate it, that could be it.

    I would have gone first for the CPS based on symptoms, but you've done that already.

    You didn't mention spark plugs and wires having been done. But that usually gives a clear code for misfiring.

    I hope you find it.

    I was lucky that I had two leSabres and I just switched all the spark control module and coils from one to the other to troubleshoot an occasional miss on the 03.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • aycockaycock Posts: 6
    Not sure this is the solution but I certainly appreciate the response. I will try what was suggested. Hope it is the solution. Thank you for your help.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,959
    While I'm trying to think of anything I've read in the forums through my leSabre years, the positive battery post is a double post with a lead spacer in the middle. Corrosion on the lead along with being squeezed can make it lose contact and one of the two positive leads would lose power. Without going back to my FSM I don't know what else would lose power there.

    Also there are the ground buss connections under the carpet next to the door sill that are wrapped in tape but corrode for some folks over years. One is next to driver and another is on the passenger side.

    The multiple grounds from the dash area that are connected to the bar can then give problems. I do not know if anything in the ignition could be grounded through there.

    https://forums.edmunds.com/discussion/comment/4066694/#Comment_4066694
    http://www.pontiacbonnevilleclub.com/forum/1992/topic35540.html

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • aycockaycock Posts: 6
    I have replaced the crank sensor, throttle sensor, EGR, map sensor, fuel regulator, and the Ignition Control Module on the 1999 Buick Lesabre and the engine continues to stall after running for about 2 hours and most of the time will crank again after it cuts off. Before long the car will have to sit for about an hour to cool off before it will start. We hooked a fuel gauge to the car and drove it down the road and when it cut off we raised the hood and the fuel gauge indicated there was good fuel pressure. My job requires me to stop and start a lot and drive on uneven surfaces I have noticed that after the car gets hot it usually begins to stall when I encounter an uneven surface. Could the computer be the culprit? I have checked the wiring harness and unplugged it several times to see if there were connection issues. I appreciate any suggestions. Thank you.
  • thecardoc3thecardoc3 Posts: 4,898
    So this is repeatable, it just has to run long enough to get it to act up. You had the right idea with the fuel pressure, set it up so that the car could be driven and then checked very quickly once the problem occurred. You have to repeat that strategy with the ignition system and the injection system. Then the next step will depend on what you discover at that time.

    As far as could it be the computer? Yes it can present this symptom. However a lot of other things can cause a symptom like you are describing too, so it's not in your best interest to shot gun another part at this. Someone has to test and prove what is failing.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 22,959
    I asked in earlier post how it cuts off. Is it definite like the switch was turned off or does it sort of misfire or die out like too rich a mixture does.

    You're going to have to determine what is missing when it is in one of its won't restart even though it cranks periods. I'd dig out an old spark plus and have one of the front spark plug wires easy to pull off and lay the spark plug attached to the wire on a metal part, not the exhaust manifold, and have someone crank the engine while you check for spark.

    If you've got spark, try adding some starting ether while someone cranks the engine to determine if the fuel is missing. Or does the fuel pressure gauge show good fuel line pressure? But are the injectors working when the car won't restart while cranking? People have used the small light bulbs with the wire contacts and plugged those into the end of one of the fuel injector leads and it shows a slight blip of light with each pulse. Or you can feel the pulse with your fingertip held against the injector while cranking.

    All it needs is spark, fuel, and air.

    Diagnosis wise, one car technician duct taped the fuel pressure gauge to the windshield facing the driver so he could watch and he test drove a misbehaving car.

    You may be dealing with a break in a wire to the pump or in a ground from the fuel pump that's cutting out.
    I've read a few cases of wear on the ignition switch contacts that would lose contact and cause the engine to cut out with vibrations like your rough roads in H-bodies. Those worn contacts would work but the wear made them let go. This is the switch that's on top of the steering column just below the cluster area--not the igntion lock switch.

    Some connectors are plastic and heating up with a high resistance poor contact expands the plastic with the heat causing the contact to physically part.

    Have you tried bumping the area of the door sill where the ground buss bar is located. I recall one fellow that found his car that would die started up after bumping that connection with his heel.

    It's taking diagnosis to find the problem. If it would act up consistently where a good technician and a Tech II could get it to happen while connected, the savings in time would be worth the cost to me.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • aycockaycock Posts: 6
    You asked how it cuts off. Initially it began sounding and feeling like it was mis-firing. Most of the time now it  cuts off like you have turned the switch off. As I said earlier it will restart and usually run for a few minutes. Then after 4 or 5 restarts it will take about an hour before it will restart. One thing I forgot to mention that after it becomes difficult to restart, when it does start, it sounds like it is trying to start and then finally gets enough fire or fuel to make it crank. I have to hold my foot on the accelerator to keep it from cutting of for about 30 seconds and then put the car in neutral and keep my foot on the accelerator each time I come to a stop. Now even when the car is first driven it will sometimes cut off at stops but will restart and may go for about an hour or more. Then stalling issues begins. Thank you.
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