Exhaust 'popping'............
Discussion
Bonnie and Clyde said:
Is it like a burble. Is'nt the spent gases? I love that noise
Well, i've read on some other sites that it could be unburnt fuel. At first i thought it was the exhaust blowing, but it isn't. Dunno, maybe just need a tune-up. 
Actually Mel, i notice from the pic of your car that it has the same looking exhaust as mine, what system is on yours? I don't know whether mine is the standard one or not as it was on the car when i bought it!
Edited by davegreg on Sunday 14th September 18:01
Popping noise from the exhaust on engine over-run / foot off the gas pedal is perfectly normal - although louder and more noticeable with any sort of performance exhaust system fitted. I believe it's to do with DFCO (deceleration fuel cut off) where if you're using the engine for braking, fuel feed to the injectors is cut off in order to save fuel and improve the mpg a little. You still get a little bit of unburnt fuel in the hot exhaust system though, and that's what's making the popping sound when it ignites. You can turn off DFCO via the ecu so that a small amount of fuel is still being fed to the engine during deceleration, only real advantage is that once you go back on the gas pedal the engine responds quicker - had this done to my old Pug 205 gti years ago and it made quite a difference.
While burning fuel outside the engine on overrun is normal I found it very muted indeed with the standard exhaust. Maybe the exhaust is blowing somewhere? It might be a possibility. When I removed my standard one from my then 13 month old car it wasn't in the best condition. It had already developed a small hole in one of the back boxes. No expense spent on exhaust materials clearly.
mine was 100 times worse after adding a blower, don't know why. It's funny going through town to use a light throttle in a low gear (usually second) then take your foot off the gas when you get next to a pedestrian. The resulting "crack" from the exhaust usually has them diving for cover! Grannies love it. As far as I know it's air being sucked into the exhaust on the overrun and igniting with unburnt fuel.
you will hear it for a few resons, some times its from the rear silencer end a nice burbly pop other times you will hear a bit more of a crak/pop type sound when excess fuel hits the cats and is evaporated (along with the cat 
) or it can also be when sufficiently hot enough that the system expands and possibly get gas out of a crappy gasket.
If worried just get up on ramps and check your bolts
) or it can also be when sufficiently hot enough that the system expands and possibly get gas out of a crappy gasket.If worried just get up on ramps and check your bolts
wolfracer said:
Think yourself lucky! I only get it when the revs drop to near idle on an overrun/deceleration. I've heard some crack, and pop in between gear changes now THAT'S cool.
Any way to make mine crack and pop a bit more other than fitting a s/c?!
go for side exits Any way to make mine crack and pop a bit more other than fitting a s/c?!
that's what i'm doing 
kiwifraser said:
Stigmundfreud said:
on the m6 you can enable dfco on gear change
Stigy, I'm assuming you don't mean the M6 motorway! Anyone able to translate this to easy english please?Gassing Station | HSV & Monaro | Top of Page | What's New | My Stuff