Engine shaking, exhaust stinks, noise when accelerating

GRACECORMAN

MEMBER
2006 PONTIAC GRAND PRIX
AUTOMATIC
100,000 MILES

My engine has been shaking gently for a while, barely noticeable. Last week, it was very tough to get out of park. The shifter did not want to move. Then last night, the engine started shaking even more, and when the gas pedal was pressed, it made a grinding, scraping noise. We parked the car and looked under the hood and could see the engine shaking when the car was put in gear. We checked the oil and it is fine. After sitting there for a few moments the exhaust began to smell like eggs.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi and thanks for using 2CarPros.com.

Based on your description, it could be a few things. The smell is from the catalytic converter. The amount of sulfur that is present in the fuel and can be a symptom of a bad catalytic converter. Additionally, if the engine is running too hot, it can happen, or more often, a bad fuel pressure regulator which is allowing too much fuel to enter the engine because it no longer reduces the pressure from the fuel pump.

With that being said, I would recommend starting with a fuel pressure test. Here are directions which show how to check pressure as well as a regulator. It is not hard, but requires a fuel pressure gauge. Most parts stores will lend you one.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

The first picture I attached contains the pressure your vehicle should have.

If you find that the pressure is correct and within the manufacturer's specifications, the I recommend checking the catalytic converter. Follow the directions in this link:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter';

Here is a link which describes symptoms of a bad converter:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

In addition to the aforementioned suggestions, make sure the engine is running at normal operating temperatures. If it is overheating, that too can cause that smell.

Let me know what you find or if you have other questions.

Take care,
Joe

Image (Click to make bigger)