[CantCatchMe]

I have a 18/A10 with an axel back Corsa Xtreme exhaust that got installed 2 weeks ago. Over the last two weeks its been roaring loud and sounds amazing. Yesterday and today though I noticed that when I start it in my garage its not as loud. It doesn't spike as loud on start up as it did for the last two weeks. Anyone have a similar issue or can anyone think of what might be causing it?

Im not the only one that's noticed it. My roommate said it doesn't seem to make the walls vibrate in the house as much and my co-worker said she used to plug her ear when I would start it and when I started it yesterday that wasn't the case because she said it seemed quieter. When I rev the engine it also doesn't sound as aggressive.

My buddy seemed to think that the computer on board is adapting and learning the new set up and that the factory PCM is working to bring everything back to factory specs and the only way to get it back to the ear busting sound would be to get a tuner device. Does that seem correct? If this is true would going with mid pipes do anything? I really am trying to avoid a tune as I've read these cars really shouldn't need a tune unless your putting a ton of stuff on them.

Any help would be greatly appreciated.

[Can'tHave2MuchHP]

Get under the car and check for leaks or damage. Make sure something didn't get into the exhaust, could be a mouse nest or who knows what. The exhaust system itself isn't going to get quieter in fact mufflers get louder as they break in.

Any codes or weird temperatures etc.?

The engine learning to exhaust sound is complete utter BS lol, that just doesn't happen. Do you have any other mods that would cause the computer to try and self correct say like an intake/throttle body?

There are DFCO (Decel fuel cut off) tables that are responsible for some volume and decel noise/pops, but if it wasn't tuned those wouldn't be messed with. Other than that, a tune isn't going to change the volume of a startup, unless there were special circumstances like a cam or something.

Also, if it's not a full COLD start then it won't get that crazy sound on startup. I also run a Corsa Xtreme with X Pipe and if it's been less than 24 hours, it doesn't go into that aggressive cold start mode and now that it's hot out, it also calms down a lot faster, within 15-20 seconds of the initial start, it quiets down to warm idle. In the cold weather, the cold start warm up remains for a long time.

Safe to say my car isn't getting any quieter. I just got back from a quick cruise in it and it's as nasty as ever.

[TRZ06]

Originally Posted by Can'tHave2MuchHP

Get under the car and check for leaks or damage. Make sure something didn't get into the exhaust, could be a mouse nest or who knows what. The exhaust system itself isn't going to get quieter in fact mufflers get louder as they break in.

Any codes or weird temperatures etc.?

The engine learning to exhaust sound is complete utter BS lol, that just doesn't happen. Do you have any other mods that would cause the computer to try and self correct say like an intake/throttle body?

There are DFCO (Decel fuel cut off) tables that are responsible for some volume and decel noise/pops, but if it wasn't tuned those wouldn't be messed with. Other than that, a tune isn't going to change the volume of a startup, unless there were special circumstances like a cam or something.

Also, if it's not a full COLD start then it won't get that crazy sound on startup. I also run a Corsa Xtreme with X Pipe and if it's been less than 24 hours, it doesn't go into that aggressive cold start mode and now that it's hot out, it also calms down a lot faster, within 15-20 seconds of the initial start, it quiets down to warm idle. In the cold weather, the cold start warm up remains for a long time.

Safe to say my car isn't getting any quieter. I just got back from a quick cruise in it and it's as nasty as ever.

One quick note on your comment about them getting louder as they wear in. I do not think that applies to the Corsa, as they use chambers that I don't think has insulation.

That used to happen with old school mufflers as the packing inside condensed as it got hot and used. I don't think Corsa mufflers have any packing in them, just chambers.

[TRZ06]

One thing I used to notice when I had Corsa's on my C5 & C6 Z06 is that depending on the AF mapping and how the computer would alter the AF ratio, it changed the way the Corsa's sounded.

Sometimes it would sound nice and crisp, and other times under deep throttle, it would take on a snapping type sound, almost like a propeller on a WW2 plane that is hitting the sound barrier.

Corsa always sounded best when cold and not as loud or good sounding the hotter the car got.

[CantCatchMe]

Originally Posted by Can'tHave2MuchHP

Get under the car and check for leaks or damage. Make sure something didn't get into the exhaust, could be a mouse nest or who knows what. The exhaust system itself isn't going to get quieter in fact mufflers get louder as they break in.

Any codes or weird temperatures etc.?

The engine learning to exhaust sound is complete utter BS lol, that just doesn't happen. Do you have any other mods that would cause the computer to try and self correct say like an intake/throttle body?

There are DFCO (Decel fuel cut off) tables that are responsible for some volume and decel noise/pops, but if it wasn't tuned those wouldn't be messed with. Other than that, a tune isn't going to change the volume of a startup, unless there were special circumstances like a cam or something.

Also, if it's not a full COLD start then it won't get that crazy sound on startup. I also run a Corsa Xtreme with X Pipe and if it's been less than 24 hours, it doesn't go into that aggressive cold start mode and now that it's hot out, it also calms down a lot faster, within 15-20 seconds of the initial start, it quiets down to warm idle. In the cold weather, the cold start warm up remains for a long time.

Safe to say my car isn't getting any quieter. I just got back from a quick cruise in it and it's as nasty as ever.

The temps all show as normal, no codes or check engine lights. I installed a RotoFab CAI the same day as the Corsa so Ive only ever heard it with that setup. And yea I am comparing cold start to cold start and its not sounding the same. Like this mornings cold start sounded quieter then the warm start from a week ago. Ill get under it this weekend and check for damage. I checked my garage when I pulled out for any leaks and didn't notice anything.

I am looking at doing the X pipe as well. Did you install yours yourself? Was it relatively easy to do?

[ninetres]

Our ZL1s don’t start as “snappy and loud” when they are semi warm. When truly cold they seem to fire really aggressively. My Corsa has not changed during the 1500miles I’ve had it on. But if the Engine has ANY residual heat in it during start up......it’s a tad softer than when totally cold.

[CantCatchMe]

Originally Posted by ninetres

Our ZL1s don’t start as “snappy and loud” when they are semi warm. When truly cold they seem to fire really aggressively. My Corsa has not changed during the 1500miles I’ve had it on. But if the Engine has ANY residual heat in it during start up......it’s a tad softer than when totally cold.

Yea I understand the difference between cold and warm starts but it seems that the truly cold start first thing in the morning yesterday and today was missing the really aggressive firing you mentioned. That's how I initially noticed that it sounded quieter was because it was missing the aggressive sound that makes me smile.

[EDFHOBBIES]

If your only talking Cold Starts its because its getting to darn hot.. The cars temp in the garage is all ready 100 and it never cools down..

my wifes car doing that..

[45LongColt]

I agree with EDF Hobbies... if its like 60 degrees in the morning and I fire mine up, its loud and crisp, when its 75 or 80 degrees when I fire it up, no crispness and more mellow sounding.

I would think its ambient temperature making the difference.

[CantCatchMe]

Ill have to keep track. Yesterday and today the morning temps were around 50-55.

[EDFHOBBIES]

YUP... a 24 hour cold start in 60 degrees is 100x louder and the idles louder longer than letting it cool for 5 hours.. unless its 30 degrees out lol

keep watching you will see sometimes it will be harder to start or sound weird every now or then to when it 1st fires..

[CantCatchMe]

Originally Posted by EDFHOBBIES

YUP... a 24 hour cold start in 60 degrees is 100x louder and the idles louder longer than letting it cool for 5 hours.. unless its 30 degrees out lol

keep watching you will see sometimes it will be harder to start or sound weird every now or then to when it 1st fires..

yea when I started it yesterday it had been sitting for 2 days so I was prepared for a loud burst of exhaust and a good 10-15 seconds of loud rumble but it didn't.

I was worried that when I got the oil changed at the dealer on Friday of last week that they might have done something that altered the sound like bumping something out of place or breaking something.

[Mcmillion]

When I "pulled the fuse" for the exhaust valve like many have recommended, mine lost the violent cold starts. I put it back and back in business. Obviously you don't have the valves on the exhaust, but may be one more thing to check.

[TRZ06]

Originally Posted by Mcmillion

When I "pulled the fuse" for the exhaust valve like many have recommended, mine lost the violent cold starts. I put it back and back in business. Obviously you don't have the valves on the exhaust, but may be one more thing to check.

Corsa is an aftermarket exhaust and does not have valves