Runs rough at idle

Tiny
MARRIEDSHADES
  • MEMBER
  • 2004 NISSAN FRONTIER
  • 3.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 134,875 MILES
Just got the knock sensor replaces last week and now the truck is running rough at idle. It was not before the change of parts. Any ideas on what would do that? I took the truck to a good mechanic shop.
Tuesday, January 15th, 2019 AT 1:45 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi and thanks for using 2CarPros.

The knock sensor is located under the intake and mounted in the engine block. Since the problem started after the work, my first guess is there is an engine vacuum leak resulting from everything being taken apart. A hose may have cracked, the intake may be leaking, or they may have overlooked reconnecting a hose.

With that in mind, you should contact the shop and express your concerns. Explain you feel there is a vacuum leak.

If you want to check for yourself, here is a link that explains how it is done. Also, I attached two pictures. The first is an exploded view of the engine, which indicates the sensor's location. Picture two is very specific.

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

Let me know if this helps or if you have other questions.

Take care,
Joe
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Tuesday, January 15th, 2019 AT 6:06 PM

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