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Discussion Starter #1
Goodmorning everyone,
I am a happy owner of a Maserati Granturismo S Automatica 2014, for some time I have been reading the posts of this community but it is the first time that I have written one.

I mounted the Larini sport cats about 2 weeks ago, the sound has increased a lot, both at startup and at high revs! Very beautifull! But.....

Last Wednesday, a friend came to my home and I made him hear the new sound of my car: I turned my car on (without moving it) and I did 3-4 fast revs (3000rpm / 3500rpm) with a cold engine.

I didn't turn it on until Friday, and it was a shock:
during ignition, the car no longer screams as since I mounted the cats, and even using it and revving the engine a little, the sound is no longer as loud as it was a few days before.
I feel like I've gone back to the old catalyst. Unfortunately that's not my impression, it's something I'm sure of.

From Friday to today I tried to use it on the motorway to clean the exhaust system / catalyst, I also used an additive but nothing has changed: the superlative sound I had with the Cat Larini has been lost.

The car from Wednesday to Friday was not touched/used/moved. What can be changed? Could I have clogged something with the revs?

please help me

I want back the superlative sound I had before!

Thanks Everyone and sorry for my bad english
 

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Well... Revving the engine cold can send excess fuel into the exhaust which can cause a meltdown of the cat. You didn't mention any check engine lights or codes so maybe it's not that or just enough of the cat melted to restrict the sound and not throw a post cat O2 sensor code. Lots of reasons not to spin up a cold engine.
 

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Discussion Starter #3
Well... Revving the engine cold can send excess fuel into the exhaust which can cause a meltdown of the cat. You didn't mention any check engine lights or codes so maybe it's not that or just enough of the cat melted to restrict the sound and not throw a post cat O2 sensor code. Lots of reasons not to spin up a cold engine.
Hi Rennz, thanks for your reply!!!!

what bad news .. I have never accelerated with a cold engine, just a few spin up to 2.5k 3k rpm while going up the garage ramp.

I didn't think I could melt it for so little.
so do you recommend to disinstall the catalyst to see what condition it is in?


In your opinion, is the problem fixable? Could catalyst cleaning additives do anything?

P.s.Fortunately no check engine light on.
 

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I am sure you are, but I assume you are putting the car in sport mode?
 

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Hi Rennz, thanks for your reply!!!!

what bad news .. I have never accelerated with a cold engine, just a few spin up to 2.5k 3k rpm while going up the garage ramp.

I didn't think I could melt it for so little.
so do you recommend to disinstall the catalyst to see what condition it is in?


In your opinion, is the problem fixable? Could catalyst cleaning additives do anything?

P.s.Fortunately no check engine light on.
A few things before panicking:
-The engine does quiet down after a minute or two after the air injection system does its thing. Though you stated it sounded different on another cold start...
-Some exhaust systems have a "break-in period" that mellows the sound a bit after a few good heat cycles.
-Do you notice a decrease in power at higher revs?
-Does the exhaust smell different?
-are you sure the exhaust valves are opening?
-Have you had a before and after hearing test once you were exposed to the awesome sound of the sport cats?

I Would give it a few more good drive cycles before ripping anything apart.
 

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A few things before panicking:
-The engine does quiet down after a minute or two after the air injection system does its thing. Though you stated it sounded different on another cold start...
-Some exhaust systems have a "break-in period" that mellows the sound a bit after a few good heat cycles.
-Do you notice a decrease in power at higher revs?
-Does the exhaust smell different?
-are you sure the exhaust valves are opening?
-Have you had a before and after hearing test once you were exposed to the awesome sound of the sport cats?

I Would give it a few more good drive cycles before ripping anything apart.
Yep, I was thinking exhaust valves as well. Sounds like they are staying shut. Ask the poster Jason.....I believe he is a mechanic that works in these cars. I’d take my car to a Maserati mechanic personally. You can also call Formula Dynamics. They sell these so they may have had this issue before. Really nice guys.
 

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Your exhaust bypass valves aren’t opening its sounds like. Basically there’s a vacuum controlled flap on each muffler that opens and closes to increase the sound. You can actually just put a screw in the vacuum line and leave them open all the time if you want.
 

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Discussion Starter #9
A few things before panicking:
-The engine does quiet down after a minute or two after the air injection system does its thing. Though you stated it sounded different on another cold start...
-Some exhaust systems have a "break-in period" that mellows the sound a bit after a few good heat cycles.
-Do you notice a decrease in power at higher revs?
-Does the exhaust smell different?
-are you sure the exhaust valves are opening?
-Have you had a before and after hearing test once you were exposed to the awesome sound of the sport cats?

I Would give it a few more good drive cycles before ripping anything apart.
first of all THANKS to everyone for the answers. the problem is not related to the valves on the exhaust, I had them removed about a year ago (they were blocked).

@Rennz
-I did other tests with a cold engine but the result is always the same.
-hope this is not the case, the difference in sound is quite high (like a stock cats). i have never read about other users with the larini cat who had this difference after 2 weeks.
-maybe at low revs, but i’am not 100% sure
-no different exhaust smell
-I did not test with a sound level meter but I went by ear. my friends have realized this too, so I exclude that it is only my idea.

I really hope it resolves with some good driving cycle :)

@rdown76
let's see if they're so kind to answer here. Unfortunately, living in Italy, I didn't order the piece from FD (due to duties) but directly from Larini UK. otherwise I will try to disturb them with an email.

thanks again everyone for the support
 

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Discussion Starter #10
small update..
today I filled up with 100 octane petrol, and I put an injector cleaning additive.

as soon as I finish this full tank of petrol I try again with an additive to clean the catalyst.

let's hope something changes.

do you have other ideas?
 

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Just don't go overboard on the additives. Even the ones that claim to be O2 sensor safe can still foul them if too much is used.
Do a few good long runs (20+ minutes) to give the cats a chance to burn any carbon off that may be restricting them. Highway, not idling in your driveway.
If all else fails, take them off and have a look, you may need to find someone with a lighted borescope to get a good look at both sides.
Did you happen to keep the old set of cats?
 

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Discussion Starter #13
Just don't go overboard on the additives. Even the ones that claim to be O2 sensor safe can still foul them if too much is used.
Do a few good long runs (20+ minutes) to give the cats a chance to burn any carbon off that may be restricting them. Highway, not idling in your driveway.
If all else fails, take them off and have a look, you may need to find someone with a lighted borescope to get a good look at both sides.
Did you happen to keep the old set of cats?
yes, I still have the old cats.

so I follow your advice, i wil do some long runs and wait for any changes.

thanks for the advice Rennz
 

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first of all THANKS to everyone for the answers. the problem is not related to the valves on the exhaust, I had them removed about a year ago (they were blocked).

@Rennz
-I did other tests with a cold engine but the result is always the same.
-hope this is not the case, the difference in sound is quite high (like a stock cats). i have never read about other users with the larini cat who had this difference after 2 weeks.
-maybe at low revs, but i’am not 100% sure
-no different exhaust smell
-I did not test with a sound level meter but I went by ear. my friends have realized this too, so I exclude that it is only my idea.

I really hope it resolves with some good driving cycle :)

@rdown76
let's see if they're so kind to answer here. Unfortunately, living in Italy, I didn't order the piece from FD (due to duties) but directly from Larini UK. otherwise I will try to disturb them with an email.

thanks again everyone for the support
Are you sure the valves were removed? typically you just plug the vacuum lines. Seems like a lot of work to remove them. If they werent removed maybe the higher flowing exhaust somehow moved them to the closed position. I know that seems unlikely but your symptoms say that the valves are just closed. They havent been used in a while so they may need to be lubed so they spring back to open position. Any chance one side sounds louder than the other? I would get under the car with it running and try and turn the valves by hand. I have never heard of the cats being clogged that quick.
 

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Discussion Starter #16
Are you sure the valves were removed? typically you just plug the vacuum lines. Seems like a lot of work to remove them. If they werent removed maybe the higher flowing exhaust somehow moved them to the closed position. I know that seems unlikely but your symptoms say that the valves are just closed. They havent been used in a while so they may need to be lubed so they spring back to open position. Any chance one side sounds louder than the other? I would get under the car with it running and try and turn the valves by hand. I have never heard of the cats being clogged that quick.
Hi mcann2, thanks for your reply!

maybe the problem is not in cats but it is elsewhere, even if it seems strange to me.

I can confirm that the valve has been totally removed (one valve was totally blocked, it did not move even forcing it by hand) so I basically eliminated the section of pipe where the valve was and had it replaced with a straight pipe.

Also for me is really really impossible that the cats have clogged up so quickly.. I traveled only 250km with these cats!
 

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Hi mcann2, thanks for your reply!

maybe the problem is not in cats but it is elsewhere, even if it seems strange to me.

I can confirm that the valve has been totally removed (one valve was totally blocked, it did not move even forcing it by hand) so I basically eliminated the section of pipe where the valve was and had it replaced with a straight pipe.

Also for me is really really impossible that the cats have clogged up so quickly.. I traveled only 250km with these cats!
did you call Larini? Never heard of this either. Curious the outcome.
 
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Are you sure the problem is not in your head? You thought it sounded louder before? I have installed several sets of these and they only make the car slightly louder...Catalytic converters are like a women being pregnant...You either are or your not..There really isn't a halfway....If the inside was obstructed or melted down the car would have less power and the car would turn on a the check engine light pretty quickly... If you are that concerned remove an O2 sensor and examine the brick inside the catalytic... Jason
 
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Are you sure the problem is not in your head? You thought it sounded louder before? I have installed several sets of these and they only make the car slightly louder...Catalytic converters are like a women being pregnant...You either are or your not..There really isn't a halfway....If the inside was obstructed or melted down the car would have less power and the car would turn on a the check engine light pretty quickly... If you are that concerned remove an O2 sensor and examine the brick inside the catalytic... Jason
To follow along, OP, is there much difference is sound between sport and non sport mode? Sport mode with the Larini cats will be very loud when you are above 3krpms
 

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To follow along, OP, is there much difference is sound between sport and non sport mode? Sport mode with the Larini cats will be very loud when you are above 3krpms
He's had the valves removed, no?

C
 
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