I've been wondering for some time what causes the burble and pop on decel in an SRT4, it's very pronounced and Mopar even claims that their staged kits are tuned to increase it, so there must be a method to it. It's not quite as loud as ALS but it's definitely distinctive.

Just curious really, this isn't my "How do I get that sound in my Miata" thread

 

Its unburnt fuel in the exhaust system igniting.

 

yup, ignition cut i think
you can do that to your miata with MS i believe

 

that thing must go through turbos and cats like mad. I do know there is also no muffler..

 

Well, I'm at 65k and no problems with cats or turbos...

 

There it is.

 

Damnit you beat me to it.

 

even a lean condition can cause the popping. my car does it too. it's definitely not rich on decel.

if you want it to make a lot of noise, drill a 1" hole in your downpipe.

 

put the cat as far upstream as possible and add a very long, free flowing exhaust behind it. I was doing some reading on this a while back and retarding your timing 10-15 degrees under decel (more vac than idle) will make it much more pronounced. So on MS add a line in under the idle row and retard the timing 10 degrees from the idle value. That should do it.

 

I don't want to make a bunch of noise, I'm just curious what makes the noise in my SRT4. Of course I know it doesn't have any mufflers, what the stock duals (long gone btw) look like, etc.

It got me thinking because a buddy of mine has a near identical SRT w/ side exit exhaust, Stage 3 ECU, catless DP etc. and his backblast on decel scares pedestrians.

Some of you are saying it's because it's rich, others that it could be lean, that there's an ignition cut involved.. so many theories.

 

everything i own with non-stock exhuast has has a slight burbling noise when engine braking

 

I want mine to sound like that! we need to find out exactly what does this...

 

judging by the color of the bumper, i'd say extra fuel

 

i run no muffler and get it a LITTLE bit... IMO it's kind of a mean sound when u roll down to a stop and u get a bap bap bap every few rpms

as far as the gurgle sound, i believe it's the cams design in the srt-4, not 100% sure tho so don't hold me to it

 

If you like noise enable launch control. You can just hold the throttle while you slow down with the clutch in.

 

lol... that's not the same sound as an srt.... unless ur car's set up for it?

 

I dont think it's the lack of mufflers. it's running super rich from all the pc-pros hidden under the dash.

 

Just like was said above...
The reason it happens on the SRT OEM is the free flowing exhaust system and the car is is factory tuned a little rich.

When MS cuts fuel when I pull off the pedal and I get some gurgle/popping in my miata. Take off the muffler and I'm sure you'd have a nice loud afterfire.

 

it does it on my miata, i think because i am running 9mm plugs and 87 octane should i be running 91 to stop the popping?

 

Mine does it to, but it's because I cant get my dick out of the tailpipe.