2000 Pontiac Grand Prix shakes at 45mph

Tiny
ADAMLEDET
  • MEMBER
  • 2000 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 107,540 MILES
I just got this car for cheap, its been sitting in storage for a year. So I give it gas and at 45 it starts to shake then I take my foot off the gas and it stops. Any suggestions?
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Tuesday, May 5th, 2009 AT 5:51 PM

11 Replies

Tiny
BMRFIXIT
  • EXPERT
Check tires and have them balanced if any good
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Tuesday, May 5th, 2009 AT 5:58 PM
Tiny
ADAMLEDET
  • MEMBER
Another question regarding the shaking would changing the spark plugs help at all?
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Tuesday, May 5th, 2009 AT 6:09 PM
Tiny
BMRFIXIT
  • EXPERT
With the mileage listed the engine is due for a tune up if none was done
so I would consider replacing plugs and tune up
good luck

*****************************************
need manual CHECK IT @
http://www.2carpros.com/kpages/auto_repair_manuals.htm
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Tuesday, May 5th, 2009 AT 7:45 PM
Tiny
ADAMLEDET
  • MEMBER
I just had the tires replaced and balanced changed the plugs and wires. Changed the air filter and oil. But still shaking when I get to 45mph. So im stuck and confused?
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Thursday, May 7th, 2009 AT 3:58 PM
Tiny
BMRFIXIT
  • EXPERT
What does shake is it the car, is engine, is the steering
do you have check engine light on?
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Thursday, May 7th, 2009 AT 4:21 PM
Tiny
ADAMLEDET
  • MEMBER
There is no lights coming on. Its defiantly coming from the front end, I just cant figure out where, I defiantly feel it from the steering wheel. It can start from as low as 35 but starts to smooth out a little at about 70. I have heard so many different reasons, so any good advice is good advice. I love the car so I will be putting allot of effort into it.
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Thursday, May 7th, 2009 AT 4:51 PM
Tiny
IAMSAFE
  • MEMBER
I think it may be the Motor mount or the balance shaft is off.

I have the same problem, Im going to get it looked at this weekend
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Monday, May 11th, 2009 AT 11:02 PM
Tiny
ADAMLEDET
  • MEMBER
The motor mount? I have heard that before but I cant locate it. And the balance shaft? Where its that? So is your shaking progressive or does it always start at around the 40 45 area?
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Tuesday, May 12th, 2009 AT 7:47 PM
Tiny
IAMSAFE
  • MEMBER
Mine comes and goes, its not always constant, and its not a violent shake.

I know I need an alignment too, but it shake more when I turn the wheel to the right, but the shake feel like they are coming from the front centre and not from teh wheels, feels likes its right under the gas pedal.

Im going to do the tie rods and alignment this weekend. So I will know more from there.

I did research on the motor/engine mount, and found it stop the car from shaking, when the enigine is shaking (running). Motor mounts support the engine and transmission, and dampen noise and vibration. The mounts isolate engine and transmission from the chassis so vibrations and noise are not transmitted to the rest of the vehicle.

Aa1car. Com/library/motor_mounts. Htm
wiki. Answers. Com/Q/What_is_a_motor_mount
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Tuesday, May 12th, 2009 AT 10:51 PM
Tiny
IAMSAFE
  • MEMBER
Balance shaft.

In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced.
En. Wikipedia. Org/wiki/Balance_shaft

A shaft designed so that, as it rotates, it vibrates in a way that reduces or cancels some of the vibration produced by an engine. Not essential to an engine's operation, balance shafts are nonetheless becoming increasingly common as a means of engine refinement.

A single balance shaft is used when fitted to three-cylinder and V-6 engines. Four-cylinder engines use two shafts turning in opposite directions on either side of the engine's crankshaft

autorepair. About. Com/library/glossary/bldef-022a. Htm

trick now is just finding out what is the actual problem :S
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Tuesday, May 12th, 2009 AT 11:06 PM
Tiny
BMRFIXIT
  • EXPERT
Get the car up to about 50 mph and where the shacking noticeable
let it cruise at that speed or more
place the tranny in neutral
do u still have the shaking
if its between 45 and 70 mph
have to check tires and if balanced
drive shaft and axles wheel bearing and tie rod ends
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Wednesday, May 13th, 2009 AT 5:06 AM

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