Car shakes when accelerating

IMFALSIFY

MEMBER
2008 MAZDA 3
2.0L
4 CYL
2WD
AUTOMATIC
182,000 MILES

Car tends to idle at 500 when at a stop light. I found out how to replicate the problem, put the car in drive with the e brake on, and when the brake pedal is pressed the car shudders to 500 RPMs. (Only in drive) Also the car shakes when accelerating which I'm thinking is motor mounts.

Monday, March 29th, 2021 AT 11:58 AM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,055 POSTS

Hi,

Do me a favor. It sounds like you could have an engine vacuum leak at the brake booster. If you look below at pic 1, I highlighted the vacuum supply hose and where it attaches to the booster. The booster is located under the hood, driver's side, and behind the brake master cylinder.

Open the hood, start the engine, and check that hose. See if you hear a hissing sound. Also, if you have a helper, have them replicate the problem by placing it in gear with the brake applied.

One other thought, I need you to check for engine vacuum leaks. Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

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

Take care,
Joe

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