Loud exhaust noise under hood and power loss
Thread Starter
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Joined: Jun 2017
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From: Richmond, VA
Loud exhaust noise under hood and power loss
About 2 months ago I put a Invidia Gemini Catback exhaust on my 350z. Car sounded great up until recently. One morning the car had a rough idle that went away after a little rev and driving. The next week the rough idle came back and the check engine light came on as well. Had the codes pulled which came back with a misfire on cylinder 5 in which I was told was the plug closest the the driver. Did a tune up in which that plug that is closest to the driver was maybe hand tight if that as I was able to take the plug out with just the spark plug socket no wrench. I replaced the plugs and the idle is back to normal but now when I drive the car at load roughly 2500 rpm there is a loud pingy type sounding exhaust sound from the engine bay or just behind it. Along with the loud sound I seem to have lost most of my power. If I pick up speed gradually it seems fine but to pick up speed fast it seems to have now power. Brought it to an exhaust shop they said no exhaust leaks and he tried to tell me that the noise was my exhaust system (I know that is false information) Only thing I can think of is the misfire damaged the catalytic converter by not burning off the fuel or something? Any ideas of what else it could be?
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
New Member
Joined: Jan 2017
Posts: 1,936
Likes: 263
From: Pennsylvania
About 2 months ago I put a Invidia Gemini Catback exhaust on my 350z. Car sounded great up until recently. One morning the car had a rough idle that went away after a little rev and driving. The next week the rough idle came back and the check engine light came on as well. Had the codes pulled which came back with a misfire on cylinder 5 in which I was told was the plug closest the the driver. Did a tune up in which that plug that is closest to the driver was maybe hand tight if that as I was able to take the plug out with just the spark plug socket no wrench. I replaced the plugs and the idle is back to normal but now when I drive the car at load roughly 2500 rpm there is a loud pingy type sounding exhaust sound from the engine bay or just behind it. Along with the loud sound I seem to have lost most of my power. If I pick up speed gradually it seems fine but to pick up speed fast it seems to have now power. Brought it to an exhaust shop they said no exhaust leaks and he tried to tell me that the noise was my exhaust system (I know that is false information) Only thing I can think of is the misfire damaged the catalytic converter by not burning off the fuel or something? Any ideas of what else it could be?
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
What is your mileage? Is it a 5AT?.. From what you described, it sounds like you may be having some detonation. What type of spark plugs did you replace your old ones with? What octane fuel are you running? Did the CEL come on after installing the new plugs?-Assuming you cleared the previous code that was being thrown by the old plugs..
Thread Starter
Registered User
Joined: Jun 2017
Posts: 3
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From: Richmond, VA
Didnt get the previous codes cleared. I replaced them with Bosch double platinum and running 93 octane. It is a 5AT with approx. 175,xxx miles. ran great, sounded great and had no problems until this misfire.
350Z/370Z Tech Moderator
MY350Z.COM
MY350Z.COM
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Compare with NISSAN-SPECIFIC DTC definitions lists available on the web to get you pointed in the right direction. If this doesn't reveal anything substantial, you may need to go to a Nissan dealer or Nissan specific shop that uses CONSULT, the Nissan-specific diagnostic tool to get a full-on read of your OBD system. (Unless you wanna spend the big bucks for your own CONSULT-III setup which is available.)
A generic P0305 code could mean just about anything in the ignition sequence from the spark plug on to the coil pack to the ECM itself. CONSULT will be more precise than a general code but at least your personal scanner will confirm something going on in the ignition sequence.
If I were a betting man, would double down on a bad crank position sensor.... or thereabouts based on your mileage and symptoms.
But as Trav said, no real way to diagnose virtually without putting hands on it.
Last edited by MicVelo; Jun 21, 2017 at 07:27 AM.
New Member
Joined: Jan 2017
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From: Pennsylvania
^What he said.
Plug type, good. Gas rating, good.. It could be something as simple as a bad coil or injector on cylinder #5, or it could be something more serious such as bad rings or a rod bearing. When you replaced your spark plugs, did you come across any oil pooling in cylinder #5's spark plug well?
Thread Starter
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Joined: Jun 2017
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From: Richmond, VA
Yes there was some oil in cylinder #5's plug well because the plug was not tightened at all some oil did get in there. I do need to replace that coil on boot thing as the one that was there for cylinder #5 came apart when pulling it out and it had some oil in it. I will try to get a video clip of the sound it is making while driving tomorrow to help. As I said though, the rough idle is gone just no power and loud exhaust sound under load at about 2500 rpm.
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MY350Z.COM
MY350Z.COM
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From: ZdayZ
About 2 months ago I put a Invidia Gemini Catback exhaust on my 350z. Car sounded great up until recently. One morning the car had a rough idle that went away after a little rev and driving. The next week the rough idle came back and the check engine light came on as well. Had the codes pulled which came back with a misfire on cylinder 5 in which I was told was the plug closest the the driver. Did a tune up in which that plug that is closest to the driver was maybe hand tight if that as I was able to take the plug out with just the spark plug socket no wrench. I replaced the plugs and the idle is back to normal but now when I drive the car at load roughly 2500 rpm there is a loud pingy type sounding exhaust sound from the engine bay or just behind it. Along with the loud sound I seem to have lost most of my power. If I pick up speed gradually it seems fine but to pick up speed fast it seems to have now power. Brought it to an exhaust shop they said no exhaust leaks and he tried to tell me that the noise was my exhaust system (I know that is false information) Only thing I can think of is the misfire damaged the catalytic converter by not burning off the fuel or something? Any ideas of what else it could be?
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
Specs of car are:
2003 Nissan 350z ATX
Skunk2 Racing plenum spacer
Injen Short Ram Intake
Invidia Gemini Catback Exhaust
New Member
Joined: Jan 2017
Posts: 1,936
Likes: 263
From: Pennsylvania
Yes there was some oil in cylinder #5's plug well because the plug was not tightened at all some oil did get in there. I do need to replace that coil on boot thing as the one that was there for cylinder #5 came apart when pulling it out and it had some oil in it. I will try to get a video clip of the sound it is making while driving tomorrow to help. As I said though, the rough idle is gone just no power and loud exhaust sound under load at about 2500 rpm.
Ok.. I would do a compression test to make sure that cylinder is healthy, and if it is, I'd try replacing that #5 coil pack(and get the bolt for it).