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MikeB85, ASE Certified Technician
Category: Car
Satisfied Customers: 354
Experience:  ASE Certified, I-Car Trained and Certified, Automotive Technology Degree
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my 2004 buick lesabre jerks when accelerates. It happens ...

Customer Reply

Customer: replied 9 years ago.
my 2004 buick lesabre jerks when accelerates. It happens when accelerating to cruising speed on parkway or when accelerating after stop light. No problems driving up hills. No engine light. I just had it at the shop today and mechanic saw bad motor mount, which he replaced along with transmission fluid and filter. he test drove it and said it was OK on parkway. I did a test drive later and found that ptoblem was still there. Car has around 55,000 miles on it. Any suggestions? Could it need a tuneup?
Expert:  MikeB85 replied 9 years ago.

You can try replacing the normal tune up stuff first. This never hurts. Make sure you follow your normal service interval periods as well that are located in your owners manual. GM usually says there plugs are good for about 100,000 but some fail way before that period.

The problem could possibly have something to do with the throttle position sensor. If the sensor is faulty it could cause possible jerks or skips in acceleration. This is only a suggestion and the proper way to determine if it is faulty or not is to place the vehicle on a scan tool and do the required component tests. If you have any other questions, feel free to ask. Thanks.

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Customer: replied 9 years ago.
Reply to MikeB85's Post: Thanks - fuel filter was replaced by dealership one month ago. What should I try next - plugs? I'm very upset because I've already spent close to $2K in repairs over last six weeks due to problems caused in large part by dealership errors and I STILL can't get this car to work right. Am working with new mechanic now recommended by AAA who seems to be OK, but I can't spend much more money on this. Any chance it could be something with fuel injectors? Dealer recommended "fuel injection service" but new mechanic thinks that stuff is essentially bunk, especially in 2004 car.
Expert:  MikeB85 replied 9 years ago.
Sometimes the fuel injection cleaner helps but chances are with a car with 55,000 miles on it, that isn't the problem. Like I said it wouldn't hurt to change the plugs but if they are causing the acceleration jerk then most likely there would be a misfire code set. As for the fuel system it will need to be checked with a pressure tester to see that everything is up to par. The best way to diagnose a problem with one of the engine sensors is to hook it up to a scan tool. This you will have to take to the mechanic to do. If you have any other questions, let me know.
Customer: replied 9 years ago.
Thanks again - one last question. Mechanic had it hooked up to computer and received only one hit, which was on transmission. Dealer had changed transmission fluid per my request but somehow left dirty filter, which new mechanic replaced. Should dealer have replaced transmission filter when initial flush was done? Am taking car back to mechanic tomorrow a.m. - hwat if scan tool shows no codes? Should I assume I'm nuts> <g> Mechanic test drove car last night prior to repair and it took close to one hour before he heard/felt thump. Could this be something not easily picked up on scan tool?
Expert:  MikeB85 replied 9 years ago.

The transmission filter should be replaced everytime the transmission is serviced. They most likely used a transmission service machine that doesn't require them to take off the transmission pan. This just replaces the fluid without changing the filter. If there was a transmission code then this could be a totally different problem. The mechanic will see if there are any codes stored for the transmission when he hooks it up tomorrow. If he does find any codes, have him write them down for your reference and let me know what they were. If you provide me with the codes I can tell you what could be causing them. Thanks.

Customer: replied 9 years ago.
Hello - I wrote five days ago about a problem with my '04 Buick LeSabre. It was jerking when accelerating. Mechanic replaced bad engine mount and did transmission flush/filter change, but car still jerks. I rode with two separate mechanics the following day for close to 40 minutes, and of course, the car rode perfectly. They ran another scan on it. It showed nothing current, but in "history", it showed that transmission had problems shifting from second to third. I think code was either 1108 or 1811 - sorry, but they were reading it to me over the phone and I lost the paper on which I wrote it down. I've never had transmission problems before. I was looking around online, and I read about a situation called "hard shifting" that was caused by a bad PVC selanoid. Could this be my problem? Mechanic told me to try to drive it locally for a few more days and then bring it back if problem still exists. I have a tentative appointment for next week. Is this type of repair very expensive? Thanks for your help
Expert:  MikeB85 replied 9 years ago.

This code is for the shift execution time. This code is set for the amount of time that it takes to execute a shift. The transmission pressure is modified by an Adaptive modifier which controls the shift execution time. If the shift takes longer than 0.65 seconds and the adaptive modifier cannot shorten this time, then a counter increases by one. If the PCM detects a counter value of 3 during one trip then the DTC 1811 will set. The diagnostic chart on this problem has so many components or faults that could be causing this problem. The only way to really tell what is wrong is to perform all of the steps of the diagnostic test with a scan tool. This will have to be performed at the repair shop. The shop will have to do this test in order to find out what exactly is the cause of the problem. They probably just suggested to replace the solenoids but I would make sure they have done the proper testing before they start throwing parts at it, hoping to fix the problem. Let me know if you have any questions. Thanks.

Customer: replied 9 years ago.
Thanks for your reply. Mechanics did NOT suggest the solenoid be replaced. They want me to drive the car as I normally do for a week or so and report when I feel the hard shifting/jerks and the length of time that they last. Is there any reason why the code would show up in "history" but not in current status? I will say that the hard shifting has eased dramatically since the engine mount was replaced. I'm now getting the shifts only when going up slight inclines or in moderate stop-and-go traffic.
Expert:  MikeB85 replied 9 years ago.
The reason it will be stored in the history is because the pcm knows that the fault occurred but it only happens now and again so it won't keep the light on. I would do like the shop said and drive it for a couple days. You can even try to get the problem to occur a couple of times. If your driving and the problem happens, try to make it happen again by either going up the same hill or road. This should set the code in the PCM. Like I said before the only way to diagnose the problem is to use the diagnostic chart and a scan tool. There is definitely a fault so the shop should be able to find it.