Car shakes and shudders intermittently during acceleration

My girlfriend’s Buick Regal will shake and shudder for about 30 seconds to 2 minutes during acceleration. This problem occurs intermittently and I’ve only noticed this during freeway driving.

The car has recently gotten a 90,000 mile service and this started happening shortly afterwards. We took the car back to the mechanic but he wasn’t able to observe the problem.

Can anyone suggest what type of problems and produce a symptom like this?

And can a poor job replacing spark plugs cause something like this to happen?

All input is appreciated.



I am not that familiar with the ignition system on your year of Regal so bear with me. It sounds like you could have a misfiring spark plug. It is possible that a spark plug is defective; a spark gap is misset; or the wrong plugs were installed.

If your engine has spark plug wires they may be on the way out (you don’t mention if they were replaced at the 90k). Also, harsh handling of spark plug wires and boots could have broken a conductor. This also applies to coil on plug installations.

In the days of distributors, an oscilliscope could be thrown on the ignition system and the problem could be easily diagnosed. BTW is the check engine light coming on. If so please post back the DTC read from the code reader. Also give us the year, engine size, and configuration.

Hope to help.

Is a check engine light involved? If so, people will need to know the codes that are being thrown by the computer to start giving suggestions. You probably have a misfire, and there are lots of things that can cause this. The codes can often help point in productive directions.

Some details about what went into the 90K service and prior maintenance history would also be good.