Whats that poping sound the exhaust makes?

**LoiBoi** · 11-01-2006 10:57 PM

i heard it on a rx-7 and a vti-r. my friend told me, it happens when too much fuel is injected into the engine ie. aftermarket fuel pump or some other reason. is that correct? im pretty sure many of you guys have heard that sound before, its common when people floor their cars, just doesn't happen in mine, aehhaeha.

I'm pretty sure the type of exhaust/mufflier system you have also contribute to the sound.
Is it worth getting fuel pump if i got a handful of mods under the bonet? they aren't very expensive anyways.

**ECU-MAN** · 11-01-2006 11:10 PM

the poping sound is from unburnt fuel going into the hot exhaust,
you even have the potential to do flamers.
your car wont do this because stock ecu turn off the injectors when you back off the acceletator.

**EuroDude** · 12-01-2006 08:10 AM

I get that popping sound as well with my civic but only during idle, and everything is stock except for the muffler. The popping sound is a low pitched+volume pop that seemingly happens randomly once or twice a second.

Maybe the injectors need cleaning or something?

**wynode** · 12-01-2006 08:14 AM

A lot of Nissan's that run AFMs also do it when people don't plumb back their BOV and all that unburn fuel burns in the exhaust like ECU man said.

**Twincam16** · 12-01-2006 08:30 AM

mine pops on up-gear every few changes... doesnt matter what revs either...

**saleeb** · 12-01-2006 08:47 AM

by pop do you mean bang, the sound rotaries make when unburnt fuel gets into the exhaust is really loud. Rotaries do this a lot more than other cars. In fact in my dad's old rx5 u could see little flames out of the exhaust all the time.

**LoiBoi** · 12-01-2006 11:22 AM

yea my friend with the rx-7 said sometimes it get flames coming out of the exhaust, i dont know wheather thats safe though. But the popping sound does sound good in my opinion.

**iamhappy46** · 12-01-2006 03:56 PM

My Civic pops & crackles at idle which sounds awesome with my exhaust system.

Unburnt fuel being ignited by the hot gases escaping from the next cylinder that fires into the exhaust manifold causes the pop.

**Hondavirgin** · 12-01-2006 05:47 PM

mine does it on the upshift too, its not a bang like with a lot of unburnt fuel like with a competition car, like a soft sound.

**ProECU** · 12-01-2006 05:51 PM

it's a symptom of a bad tune.

I'm sure some of the professional tuners & engine builders such as pornstar can explain it further.

**czy_sol87** · 12-01-2006 07:16 PM

mine does it too most of the time when im in 2nd and slowing down to stop, i have no muffler love the sound

**Ronin 09** · 13-01-2006 08:22 AM

It can also have to do with reversion of air through an exhaust... when you're WOT, there is high velocity high volume exhaust exiting. When you get off the gas, the exhaust velocity/volume of air being expelled is reduced somewhat... the faster exhaust prior to off-throttle causes a pressure difference which can create a 'pop' noise when a low baffled exhaust is used.