Interesting Sound and Feel

[JohnnyViper]

I have an interesting question in my opinion that I hope some of you can answer. Thinking back driving my viper before I sadly put it away for winter I noticed an interesting characteristic and wonder what would cause it. If I was coming off an hard acceleration then cruised off the speed without a gear change, the exhaust tone would level off to normal for a number of seconds then I would get this deep exhaust tone that wined down and it felt like someone applied the brakes. What would cause this? I feel the exhaust my play a part in the answer, at the time is was stock other than the rear resonators being deleted on a 97 GTS...Thanks in advance!

 

[J&R3xV10]

It sounds like you are talking about the same effect as down shifting. If you are at higher RPMs then let off the gas and remain in gear the car will slow down and sound a bit like a jake brake on a truck.

 

[JohnnyViper]

maybe but i just dont think that is it, I have had a few manual sport cars and never experienced something like this, it cruses in the gear with no resistant for 5-10+ second (the time varies) then all of a sudden i get that exhaust tone I described and it feels like something abruptly places resistance on my driveline

 

[JohnnyViper]

and the exhaust goes from normal to a deep “loud” tone that is different from the WOT tone, with your suggestion I would figure the resistant would be right from the time my foot left the gas

 

[steve911]

If I remember correctly the Gen 3 cars have a built in fuel shut off that activates when in the decel mode to help control emissions. It is controlled by the PCM. I dont know if Gen 2 cars have this or not, but it sure sounds like the same thing that happens in my '04 and '06.

 

[Madduc]

Sounds like idle hang.

 

[TowDawg]

Yep. My Gen III does the same thing.

 

[Paul Hawker]

Hang idle was part of the program in 96/97.

When you let off on the gas the revs would drop some, then a couple seconds later drop some more to the set idle speed.

Drove me crazy on the track, especially Willow Springs. When you would lift you would get no engine braking for a few seconds, then engine braking would set in.

Think it was necessary for emissions. Could not chop the throttle all the way at once, but step it down.

 

[JohnnyViper]

ok, good to know i'm not crazy, is it something that needs to be corrected and if so how?