Stock exhaust question

[AV95z]

I've had my car for a few weeks now. It's a 2SS. It's all stock.

From even low rpms like 2000 when I let off the gas the exhaust pops and burbles. I would expect this from an aftermarket system but not the stock one. Is this normal? Car is an M6 LS3 btw.

[cowjazz]

Yes it is normal.

[Edwin320]

I'll jump in on the "yes, it's normal" chorus.

[Powhusku]

That popping and gurgling is just excess fuel being burnt off. Nothing to worry about.

[Stealth6]

The sudden easing off the throttle causes an immediate decrease in exhaust emissions to the degree that atmospheric pressure surrounding the exhaust pipe pushes cool air up into the exhaust system. This air collides with the warm exhaust gasses andcreates a rumbling sound. Very normal indeed...

[Coltrane]

It's caused by DFCO (Deceleration Fuel Cut Off) and is in the tune to save gas consumption. The stock mufflers muffle the popping noise quite a bit and it becomes much more noticable with after market exhaust systems

[AV95z]

Cool. Good stuff.

My cammed 4th gen w/ headers, exhaust, and no cats makes a great sound when you let off the gas. I just wasn't expecting it from a completely stock car!

[Russell James]

Originally Posted by Coltrane

It's caused by DFCO (Deceleration Fuel Cut Off) and is in the tune to save gas consumption. The stock mufflers muffle the popping noise quite a bit and it becomes much more noticable with after market exhaust systems

Exactly. There is a specific decel closed throttle rpm range where the fuel is cut off in DFCO mode. The tiny bit remaining is not enough to support combustion AFR, so it goes out as raw fuel and pops in the exhaust when it gets near enough oxygen.

You can turn off the DFCO mode using aftermarket tuning and keep the decel fueling in combustion AFR at all times... but you just voided the warranty. That would also just slightly decrease mileage, maybe 1ish mpg.

As long as you keep decent size mufflers on, it's hardly noticeable. Put some HF cats on and the stock exhaust will sound real nice.

[hightower]

Yep normal, decel pop

[bdsdnfam]

That sound is music to my ears!!

[rberns]

My stock L99 exhaust sounds lame until I threw Solo Performance High Flow cats and now she has that gurgle and popping sound and I love it! I will sit in the parking lot sometimes and rev the engine a little just to hear it pop.

[docindoyle]

Normal. Almost like a lean fuel condition to me..

[cagj 11 ss]

Love the pop, my 10 yesr old son insists on hearing it at least once every two miles (yes he is a muscle car mod lovin little sucker already)

[nytrorcr]

I miss that part of having a M6.