Noisy GTS exhaust note

[Colgy]

I don't have a 981 Cayman, but on the 987's the PSE on/off is pretty noticeable, even at idle. Have you tried standing behind it whilst someone switches it on and off? You could also try putting your hand up to the actuator on the exhaust (when it's off and cold!) and try pushing the rod in and out to check it's free to move?

 

[Buddy]

Likewise I have a 987S with PSE and it's certainly noticeable, when I start up I'm sure it defaults to sports and then goes to normal which is much quieter, as Craig says check that the actuator is working maybe the cable clips are detached and so not operating the valves, if a relay is used or check the list for the line fuse, there should be a list of fuses and relays inside the fuse box cover.

 

[Andy Platts]

My Cayman GTS is wonderful except for the exhaust noise. Sports switchable fitted as standard is very noisy at motorway speed with no noticeable effect switching it on or off. More importantly static noise testing at 5,000 RPM gives 93db but I keep getting warnings on drive by noise testing at Goodwood despite having it switched off in sport and sportplus modes. Is there a simple solution or aftermarket fix?

Thanks for any advice

Regards

Andy

 

[tcreswick]

The different sound you're talking about at startup is just until the cats warm up. If you start your car from cold and just listen to it at idle the exhaust note will change noticeably after about 1-2 mins.

 

[ralphmusic]

My Cayman GTS is wonderful except for the exhaust noise. Sports switchable fitted as standard is very noisy at motorway speed with no noticeable effect switching it on or off. More importantly static noise testing at 5,000 RPM gives 93db but I keep getting warnings on drive by noise testing at Goodwood despite having it switched off in sport and sportplus modes. Is there a simple solution or aftermarket fix?

Thanks for any advice

Regards

Andy

Andy,

Were your Goodwood days with the Club which run to 105db static and 101db drive by?

My Cayman is 98db static at Goodwood with 3.8L engine, 200 cell cats and sports exhaust off, not had problems with drive by since fitting turn down tips. The issue I had previously was with the meter between Madgewick and Fordwater, which was where I was changing gear, short shifting resolved that until turn down tips were fitted.

People run 991GT3RS and other GT3 variants without much trouble.

Do you know which noise meter you tripped? there is one between Madgewick and Fordwater, a second just before Lavent corner, and the third is just after the chicane, on the inside of the track. If you are travelling close to another car the combined noise can trip a meter, a common issue exiting the chicane.

Ralph

 

[Buddy]

Interesting that you think it to do with cold cats Ralph as I've only noticed it on my PSE not on any other cat equipped Porsche owned by my son and I and that totals seven different models the others didn't have cats. I know that the tick over and sound change after about 20-30 seconds but this is different a more metallic sound possibly caused by the changeover mechanism, I've heard no one else comment on it but then I've not had switchable PSE before either.

 

[tcreswick]

My Gen.1 does this and I don't have PSE. It's more noticeable because I have a Carnewal exhaust.

This is from the tech manual, posted elsewhere:

Starting phase of DFI engines with high-pressure stratified charge injection High-pressure stratified charge injection is used in the DFI flat-six engines in order to optimise cold starting with regard to fuel consumption and emissions. In this process, fuel is injected once into the specially shaped piston recess just prior to the end of the compression stroke when the engine is being started. This forms a stratified charge around the spark plug to ensure that an ignitable mixture is formed. This reduces both the amount of fuel required and the emissions during the starting phase compared to intake manifold injection. Catalytic-converter heating phase of DFI engines with dual injection Once the high-pressure stratified charge injection starts the engine, the engine management system switches to the catalytic converter heating phase. In this operating state, multiple injection helps to bring the catalytic converter to the temperature required for optimal conversion of pollutants as quickly as possible. To this end, the first injection of fuel takes place during the intake stroke and the second injection of fuel occurs into the piston recess when the intake valves are closed, just before the end of the compression stroke. The slightly lean air/fuel mixture (lambda value approx. 1.05) can then be ignited at a very late point, thus increasing the exhaust temperature. The resulting delayed combustion and the continued exothermic oxidation of unburnt fuel (excess oxygen) even after the exhaust valves are opened produce a considerably higher exhaust temperature directly with the use of dual injection to heat the catalytic converters. The high exhaust temperature quickly heats the catalytic converters to the temperature for optimal conversion of pollutants. As a result, emissions during the warm-up phase are significantly reduced and the secondary air pumps are no longer required for all engines.

 

[ralphmusic]

Interesting that you think it to do with cold cats Ralph as I've only noticed it on my PSE not on any other cat equipped Porsche owned by my son and I and that totals seven different models the others didn't have cats. I know that the tick over and sound change after about 20-30 seconds but this is different a more metallic sound possibly caused by the changeover mechanism, I've heard no one else comment on it but then I've not had switchable PSE before either.

Buddy,

My comment was relating to OP's question about noise at Goodwood and I simply observed that my car has 200 cell (v OEM 400 cell) cats so noisier for that reason.

Ralph

 

[CarreraGTS]

Interesting post as i have the opposite scenario on my GT4... The exhaust note is too quiet and pressing PSE makes about 5% difference and at 70 Mph on a motorway cruise it sounds like a 1.2 Ford Fiesta and under acceleration can't pull away from a Vauxhall VXR ... apart from that its a great car ... ;(

 

[Andy Platts]

Thanks Ralph both between Madgwick and Fordwater and pulling away from the Lavant complex. Short shifting at both places stopped the warnings as did using Sport rather than Sport plus. Sport plus re mapping of engine and gearbox is pretty addictive and its a shame not to us it. Do you know of any modified tailpipes or manufacturer that I could contact?

Regards

Andy

 

[ralphmusic]

Andy,

On my 981, switching on Sport or Sport+ automatically switches the exhaust to noisy, but I can turn the sports exhaust off using the button by the gear selector.

Unless (like Murray W) I am very much mistaken, the second noise meter is between second part of St Marys and Lavant. Maybe there is a new one after Lavant since I was there in March.

I had turndown tips fabricated and fitted at Infinity Exhausts (conveniently near Castle Combe circuit) for the grand sum of £170. These simply direct the sound to the ground rather than directly out from the back.

Ralph

 

[Colgy]

Yeah as Buddy mentions above, the valves are sprung open when the engine is off, and when the engine is switched on a signal is sent to an actuator on the exhaust. It's this actuator that allows vacuum from the engine to pull the flaps shut, which is why it sounds 'sporty' upon start-up. I actually wired in a separate switch to my PSE to leave loud independently of the Sport button or cycles of the ignition - you'd expect a fuse failure or other electrical fault to make it permenantly loud in the same way.

Assuming it isn't completely different on the 981 that is...