Transmission Shifting Shutters In My 2004 Buick Lesabre

2004 Buick Lesabre. 3.8 6cyl. Did a transmission flush and filter change.
04 Buick Lesabre shifts rough sometimes from 1st to 2nd. Feels like a slight shudder, been told need another transmission, had it flushed, has helped some. Has 225 60r16 tires when door panel says 215 70r 15 tires, some models came with the 225 option, was wondering does or can computer shift points

need to be changed with na computer or something. I've heard with different tires the computer needs to be reset or it throws shifts and speedometer and odometer off.
The flushing showed no signs of debris in the pan, was wondering does it need an additive or do some Buick just tend to have that noticeable shift,
tends to do more if I push the gas harder than normal.

Answer: The tire size concern would not have anything to do with this shifting. There are a few possibilities for the shifting concern. First or all, since the flush seemed to help, i would suggest doing that again, but use the newest GM trans fluid which is Dexron 6.

This is a synthetic fluid and may help further. Do a complete flush, then drive at least one hundred miles to see if helped. Next, may be a problem in what is called the 1-2 accumulator piston, seal or housing. This is accessed by removing the pan,and the housings 4 bolts. The 2-3 accumulator is also in this housing. A good trans. Tech would be able to check this with no problem. More likely is a problem with the 2nd clutch assembly. Trans would need to come out and taken apart for this. There is a service bulletin for this issue. You may even want to call your localBuick dealer, or Buick customer assistance. They may be able to offer some help with this problem since the car is an 2004 and there is a service bulletin.

Buick Won't Accelerate

Buick Lesabre 3.8. 1990 model year. I replace fuel filter.Engine does not want to accelerate after driving approx, 20 miles in warm weather. Did not do this in winter. After it set for awhile and cools down, it is ok until it is driven and well warmed up again.

Answer: First thing to do is scan the system for codes. Next, check fuel pressure when it is acting up. Low fuel pressure can cause poor acceleration and lack of power. A plugged catalytic converter can also do this. You can try to bang on the bottom of the converter to see if it sounds like rocks rolling around inside. This is a sign of a faulty converter. Removing the exhaust at the back manifold and driving will cause it to run much better if the converter is plugged, since it i no longer attached. Warning- it ill be very loud doing this. A back pressure test with a gauge is the best way to check for a plugged catalytic converter.

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  • Guest - 04 LeSabre

    My LeSabre runs up to about 3000 RPMs just fine and then seems to be slipping or it sounds like it's in neutral. When I rev up way past 3000 RPM and then let off sometimes it catches sometimes it doesn't it seems like it helps if I shut it off and turn it back on. What could this be?