Not sure what to call it? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

spacecowby · 04-20-2010, 06:24 PM

I have the American Thunder catback on my 2SS M6 and whenever I let off the gas and the RPM's drop low my exhuast makes kind of a "Glub, Glub" sound. I think it's reffered to as decel popping or backrap. My main question: is this normal and what cuases it?

SS Drifter · 04-21-2010, 02:40 AM

How does that sound again? Glub, glub?

I think decel popping sounds like pop, pop, pop

Sully · 04-21-2010, 02:48 AM

im still stock, and mainly in 1st and 2nd comming to a stop still in gear i get it to "glub glub" or as i would say "pop" sometimes like 3-7 times as it goes down in RPMs... back pressure? gas or pressure build up? i dunno, im not an expert but i get that too, i think its kinda cool haha, but yea i get that (i think its the same thing) with my stock exhaust too

Ivan @ Southwest Speed · 04-21-2010, 03:00 AM

Quote:

Originally Posted by spacecowby

I have the American Thunder catback on my 2SS M6 and whenever I let off the gas and the RPM's drop low my exhuast makes kind of a "Glub, Glub" sound. I think it's reffered to as decel popping or backrap. My main question: is this normal and what cuases it?

..unburned/abnormal gas in the exhaust.

Not an issue, happens with some (exhaust) cars without a tune.

Heck, I hear it on OEM cars as well.
-Ivan

AlSuwaidi · 04-21-2010, 03:47 AM

i love it,,, i turn down the radio so i can hear it!

SlingShot · 04-21-2010, 05:13 AM

Completely normal ...

Russell James · 04-21-2010, 09:54 AM

Not really normal if an engine is achieving complete combustion. But normal for the way the OE calibration is set up. In the OE cal, there is a table for decel fuel cut off. For mpgs and emisions, they cut off the fuel during a small decel window. When they cut that fuel, there isn't enough to support combustion - so what little is there goes out the exhaust as raw fuel and when it hits oxygen - pop pop. The stock exhaust muffles that popping quite a bit. Put an aftermarket exhaust on there and the pops are much louder.

Turn off the DFCU in the tuning, and there will be no popping. But mpgs will take a hit.

04-20-2010, 06:24 PM	#1
spacecowby Drives: 2010 black 2SS/RS Join Date: Apr 2010 Location: New York Posts: 634 View My Garage	Not sure what to call it? I have the American Thunder catback on my 2SS M6 and whenever I let off the gas and the RPM's drop low my exhuast makes kind of a "Glub, Glub" sound. I think it's reffered to as decel popping or backrap. My main question: is this normal and what cuases it?

04-21-2010, 05:13 AM	#6
SlingShot Drives: 2012 ZL1 - #670 Join Date: Jun 2009 Location: Seminole, Fl. Posts: 8,009	Completely normal ... __________________

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04-21-2010, 02:40 AM	#2
SS Drifter Drives: 2010 2SS/RS L99 Join Date: Nov 2009 Location: California Posts: 588	How does that sound again? Glub, glub? I think decel popping sounds like pop, pop, pop

04-21-2010, 02:48 AM	#3
Sully Drives: Orange 2SS/RS LS3 Join Date: Apr 2010 Location: Southside Chicago Posts: 171	im still stock, and mainly in 1st and 2nd comming to a stop still in gear i get it to "glub glub" or as i would say "pop" sometimes like 3-7 times as it goes down in RPMs... back pressure? gas or pressure build up? i dunno, im not an expert but i get that too, i think its kinda cool haha, but yea i get that (i think its the same thing) with my stock exhaust too

04-21-2010, 03:47 AM	#5
AlSuwaidi Drives: BLACK LS3 GCC-Spec Join Date: Oct 2009 Location: UAE - SHARJAH Posts: 2,824 View My Garage	i love it,,, i turn down the radio so i can hear it!

04-21-2010, 09:54 AM	#7
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	Not really normal if an engine is achieving complete combustion. But normal for the way the OE calibration is set up. In the OE cal, there is a table for decel fuel cut off. For mpgs and emisions, they cut off the fuel during a small decel window. When they cut that fuel, there isn't enough to support combustion - so what little is there goes out the exhaust as raw fuel and when it hits oxygen - pop pop. The stock exhaust muffles that popping quite a bit. Put an aftermarket exhaust on there and the pops are much louder. Turn off the DFCU in the tuning, and there will be no popping. But mpgs will take a hit.