[wang970305]

i just saw a post that rattling sound could be caused by a misalignment of the exhaust? i don't truly think I had rattling sound before putting on the mid pipe. Maybe I need to jack up the car again to put my hand on the mid pipe to see where is rattling

[KingLT1]

Originally Posted by adamjwilson

Corsa has fixed the bushing issue (so they say), but would not hurt to check.

Wang- if this is a new axle back NPP , it is under warranty, so call Corsa.
My Corsa exhaust is so loud with all my mods, I couldn't tell you if I had a drone or rattle, but I checked the NPP valve for excessive play on both sides of mine before I installed mine as I remembered the tech bulletin that came out a while back regarding the potential rattle. I just need to tune out the 'cat warm up' excessive loud crap at start up. HP Tuners can tune that out with some ECT adjustments.

That's what they told me as well, no issues so far with the last set.

Side note, You can no longer turn off "cat warm-up" in the tune unless you have a MPVI or MPVI2 with a old software version. The feature has been removed in the last several updates. Somewhere in the 4.1x range I believe.

But you can turn off rumble mode and change the NPP valve settings which helps.

[adamjwilson]

Originally Posted by KingLT1

That's what they told me as well, no issues so far with the last set.

Side note, You can no longer turn off "cat warm-up" in the tune unless you have a MPVI or MPVI2 with a old software version. The feature has been removed in the last several updates. Somewhere in the 4.1x range I believe.

But you can turn off rumble mode and change the NPP valve settings which helps.

King- my tuner and I have discussed this topic a lot lately. He has (2) laptops (one for the newer version of HP Tuners and (1) just dedicated to the older version of HP Tuners) The reason he gave me he did this as the older version has some features he likes that were removed on the newer version(s). I will mention the 'rumble mode' and changing the NPP settings as well.... I appreciate it. I assume changing the NPP settings will not affect the sound from say Sport to Ice modes when you change it in the car?
At this point.. anything will help, as the car is obnoxiously loud when it starts and I am sure it pisses my neighbors off...lol

[wang970305]

Originally Posted by KingLT1

That's what they told me as well, no issues so far with the last set.

Side note, You can no longer turn off "cat warm-up" in the tune unless you have a MPVI or MPVI2 with a old software version. The feature has been removed in the last several updates. Somewhere in the 4.1x range I believe.

But you can turn off rumble mode and change the NPP valve settings which helps.

I pulled the fuse and it still has the rattling sounds so I assume it has nothing to do with npp?

[adamjwilson]

Wang- the only advice I can give you at this point is pull fuse #51 under the hood and find out. That will leave the NPP valves open all the time. Pretty easy to put fuse back in if it does not work

[wang970305]

Originally Posted by adamjwilson

Wang- the only advice I can give you at this point is pull fuse #51 under the hood and find out. That will leave the NPP valves open all the time. Pretty easy to put fuse back in if it does not work

That is what I did but it still has a rattling sound, so it is not from the npp valves?

[adamjwilson]

Originally Posted by wang970305

That is what I did but it still has a rattling sound, so it is not from the npp valves?

Have you gone under the car and check all clamps (tightened) and to see if anything is rubbing which can cause a rattle? You stated you have a new Corsa axle back exhaust system, so with the valves open (fuse pulled), I doubt it could be the weak bushings for the NPP valves that is allowing the NPP valves to rattle when wide open. Corsa fixed that TB a while back, but anything is possible. I would check the other parts of the exhaust from the headers back first.

[KingLT1]

Originally Posted by wang970305

That is what I did but it still has a rattling sound, so it is not from the npp valves?

Again, Check to see if the valve shafts have play. 5 min into the video.

[federal]

The Borlas on my ZL1 does the same thing. It’s does it at stops for a second or two at idle and then it goes away.

I did the “fix” where you cut off the tabs on the valves, but no dice. I need to figure out if it’s a loose clamp, a heat shield, or the actual valves rattling.