Exhaust note has changed after intake manifold gasket replace
09-11-2014, 01:01 PM
#1
Exhaust note has changed after intake manifold gasket replace
Hey guys. Sorry to post this, but making a thread on here is my last resort.
So I recently found out i had a leaking intake manifold gasket. So, to save money I did the replacement myself. Not too hard. Took about 4 hours. After putting everything back together, my exhaust sounded different; and still does.
It's deeper. Almost sounds like a boxer motor. No more leaking at the intake manifolds and everything seems to be where it should. After searching, I found that this has happened to others and there are actually several causes. My problem is, it didn't just start happening out of nowhere, it was right after the gasket replacement. This means it almost has to be regarding that, but I don't know what could be wrong. Any assistance?
If it matters to your answer, 2003 Enthusiast with Tomei catback as only mod to engine/drivetrain.
Thanks guys
So I recently found out i had a leaking intake manifold gasket. So, to save money I did the replacement myself. Not too hard. Took about 4 hours. After putting everything back together, my exhaust sounded different; and still does.
It's deeper. Almost sounds like a boxer motor. No more leaking at the intake manifolds and everything seems to be where it should. After searching, I found that this has happened to others and there are actually several causes. My problem is, it didn't just start happening out of nowhere, it was right after the gasket replacement. This means it almost has to be regarding that, but I don't know what could be wrong. Any assistance?
If it matters to your answer, 2003 Enthusiast with Tomei catback as only mod to engine/drivetrain.
Thanks guys
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09-15-2014, 07:25 AM
#13
Registered User
I had the same issue. Both Z's I have had the typical VQ howl. WOT at high RPM's, both banks were even and the sound was exotic (nismo exhaust).
On the DE, I replaced the lower plenum with a MREV2 and angled spacer. There were no leaks, but the sound at WOT all the way up was terrible. Seemed as one bank was lean and one bank was rich, minus a cylinder. Pressure tests came back with 0 leaks.
Removed plenum/spacer, checked coil packs and injectors and then reinstalled the OE revup plenum without spacer. All cylinders were firing. Pressure test reported no leaks, but derp sound remains in open loop pulls.
To be un-politically correct, hitting 75%-wot sounds like the engine enters full-retard mode. The revup no longer has the VQ sound. I then started swapping out exhausts/testpipes/cats. Same story.
My theory was the O2 sensors went bad, and or took out the O2 drivers in the ECU, as the numbers reported by my ultra-gauge seem off. However the sound really becomes silly when I hit open loop WOT so it doesn't really make sense.
On the DE, I replaced the lower plenum with a MREV2 and angled spacer. There were no leaks, but the sound at WOT all the way up was terrible. Seemed as one bank was lean and one bank was rich, minus a cylinder. Pressure tests came back with 0 leaks.
Removed plenum/spacer, checked coil packs and injectors and then reinstalled the OE revup plenum without spacer. All cylinders were firing. Pressure test reported no leaks, but derp sound remains in open loop pulls.
To be un-politically correct, hitting 75%-wot sounds like the engine enters full-retard mode. The revup no longer has the VQ sound. I then started swapping out exhausts/testpipes/cats. Same story.
My theory was the O2 sensors went bad, and or took out the O2 drivers in the ECU, as the numbers reported by my ultra-gauge seem off. However the sound really becomes silly when I hit open loop WOT so it doesn't really make sense.
Last edited by Bigsyke; 09-15-2014 at 07:28 AM.
04-08-2015, 07:43 PM
#15
Registered User
Yes, still having this issue. I have been tuning and my banks have a .5 to 1 afr point discrepancy.
Sometimes it gets worse. I can breeze through 1st and second just fine with a semi nice sound, but the second I hit 3rd or some other gear it sounds like a 'special needs' symphony and half of the engine is the baritone and the other half of the engine is alto. It clears up by 4th gear, sometimes it just keeps derping. Power of course is slightly down during this. Happened today when I was datalogging. It was embarrasing.
I cannot find an intake leak, nor an exhaust leak -- but evidence seems to point at an exhaust manifold leak. Cipher logs don't show much during this, minus bank 2 being .5 leaner, but that has always been that way.
Sometimes it gets worse. I can breeze through 1st and second just fine with a semi nice sound, but the second I hit 3rd or some other gear it sounds like a 'special needs' symphony and half of the engine is the baritone and the other half of the engine is alto. It clears up by 4th gear, sometimes it just keeps derping. Power of course is slightly down during this. Happened today when I was datalogging. It was embarrasing.
I cannot find an intake leak, nor an exhaust leak -- but evidence seems to point at an exhaust manifold leak. Cipher logs don't show much during this, minus bank 2 being .5 leaner, but that has always been that way.
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