Occasional rough idle

Tiny
HEARTSHAPEDNOOSE
  • MEMBER
  • 2003 NISSAN 350Z
  • 3.5L
  • 6 CYL
  • RWD
  • AUTOMATIC
  • 175,000 MILES
I have had my car for approximately three or four months now. I have not had any issues until the last two or three weeks. One morning I was bringing my daughter to school when I noticed the car was idling kind of rough and when I was driving it seemed to lack its normal power. Oddly though after a few quick revs the engine was running normally again. A few days later I was driving the car in which it was running fine until about five minutes from home at a stop light it started to idle rough again and lack its normal power. A quick rev seemed to help again. Is this a misfire, clogged catalytic converter, clogged air intake or could there be something more wrong with it?
Monday, June 12th, 2017 AT 6:42 AM

8 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
It could be something as simple as crud or some water in the fuel or something worse. Do you know if it's had any engine work done in the past, they tend to have timing chain issues and oil pressure and type that causes the variable valve timing to get sticky.
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Monday, June 12th, 2017 AT 7:42 PM
Tiny
HEARTSHAPEDNOOSE
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  • 57 POSTS
The only work I am aware of is an aftermarket Skunk2 racing plenum spacer and an Injen short ram intake with heat shield. I had a catback exhaust system installed about two months ago.
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Monday, June 12th, 2017 AT 8:08 PM
Tiny
STEVE W.
  • MECHANIC
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Well the intake will not be helping it as none of the "cold air" intakes will do much unless they actually draw air from outside the engine bay, which most do not.
The cat back should not hurt. Is it chipped as well?
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Monday, June 12th, 2017 AT 8:22 PM
Tiny
HEARTSHAPEDNOOSE
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  • 57 POSTS
No chip that I am aware of. It does have a remote start.
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Thursday, June 15th, 2017 AT 8:54 AM
Tiny
HEARTSHAPEDNOOSE
  • MEMBER
  • 57 POSTS
Just had the car checked at auto store because check engine light came on (flashing) It came back with a misfire on cylinder 5. I noticed though that this time when it happened it doesnt go away and now there is an exhaust sound coming from under the hood. I really hope it is not something major.
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Thursday, June 15th, 2017 AT 6:45 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
Well a single cylinder misfire could be the reason for the earlier problem.
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Thursday, June 15th, 2017 AT 8:51 PM
Tiny
HEARTSHAPEDNOOSE
  • MEMBER
  • 57 POSTS
Well I did the tune-up that seemed to have stopped the misfire. But now the engine has the loud exhaust sound from the engine bay. Could a misfire cause a hole to form in the manifold or catalytic converter or a gap where the manifold mounts to the engine or the catalytic converter? I never had a noise under the hood until this misfire came so I am guessing the misfire has something to do with it.
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Saturday, June 17th, 2017 AT 7:47 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
It would depend on just how bad the misfire was but I would suspect that it was the extra vibration more than the miss. To give you a chance you can grab a short section of hose, hold one end up tight to your ear and use the other end as a wand to listen for the area the sound is loudest.
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Sunday, June 18th, 2017 AT 3:35 AM

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