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Discussion Starter · #1 ·
i have a 91 caprice classic with 305 engine. the other day i was driving home and noticed that the car was fine under 45mph but as soon as i gave it some gas at 45mph it would shake pretty bad. this seems to have happened out of nowhere. i always drive it in overdrive if that makes a difference. i dont know if this is a transmission issue or if it could be a sensor or what but if someone could please help i would appreciate it.
 

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Let's try to nail down where you are feeling it, steering wheel?, seat, floor? Have you tried different gears, like no OD, or 2nd gear and see if it still happens at the same MPH?
 

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Could very well be.^^^Also,sometimes they don't want to "un-lock" right away,which would feel about the same.
 

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Discussion Starter · #5 ·
Let's try to nail down where you are feeling it, steering wheel?, seat, floor? Have you tried different gears, like no OD, or 2nd gear and see if it still happens at the same MPH?
i havent tried any different gears yet and probably wont be able to until tomorrow because theres a snow storm right now. if i remember correctly the shaking seemed to be the whole car or maybe the floor. i had an oldsmobile a few years back that had a problem that resulted in shaking in the steering wheel and this feels different.
 

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Discussion Starter · #6 ·
i forgot to mention this earlier, but the car sat in the snow and cold for about 5 days around christmas while i was visiting family. the first time i drove it since then is when the problem started. i dont know if that is useful information or not, just figured id throw that out there.
 

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Ignition misfire.
It would have been my first guess even before you said it happened after sitting a few days. It's likely some moisture condensed inside the cold distributor when the warmer air hit it.
And then the slight misfire is really evident when the TC is locked about 45 mph and you give it some throttle.
 

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i have a 91 caprice classic with 305 engine. the other day i was driving home and noticed that the car was fine under 45mph but as soon as i gave it some gas at 45mph it would shake pretty bad. this seems to have happened out of nowhere. i always drive it in overdrive if that makes a difference. i dont know if this is a transmission issue or if it could be a sensor or what but if someone could please help i would appreciate it.
could be just some water in the fuel. add a bottle of dry gas and add some more fuel like over 1/3 of a tank.

if you did have less than 1/3 of a fuel tank of fuel the condensation / water is very possible.
 

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Same thing happened to my Caprice during the summer ..a new distributor and some fresh plugs will get rid off the shake @45, don't bother switching gears its still gonna do it at higher speeds





Ignition misfire.
It would have been my first guess even before you said it happened after sitting a few days. It's likely some moisture condensed inside the cold distributor when the warmer air hit it.
And then the slight misfire is really evident when the TC is locked about 45 mph and you give it some throttle.


Sent from AutoGuide.com Free App
 

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Snow in the wheels,body,around drivetrain causing the vibration? If it sat out and got plowed in,there might be snow packed up in there
 

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Well today I went to go buy some drygas and the shake at 45mph was gone. I bought some and put it in the car anyway hopefully that's the end of it. Thanks for the help everyone.

keep the fuel above the 1/3 tank at all times. also with these winter temps any small amount of water will get you stuck. and if its below 10 deg f you will be not be too happy when your frozen. I keep the fuel above 1/2 when the temps drop below 20deg f. . you may also not use that gas station again.
 
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