Exhaust popping and banging..

[Fruitbooter]

Whats everyones like for this?

I have no idea what brand exhaust ive got but its a 3 inch system with a decat and middle box.

It doesnt pop or bang when im driving fast or inbetween gear changes, but it does when im driving along at a snails pace?

When im driving below 2k revs and just driving smoothly if I let my foot off the pedal and roll in 4th or 5th for a bit it starts to do little pops and sometimes you get the odd loud one which is nice

So what causes this is it just simply overfueling? running a bit rich? At first i thought it was missing but this would happen when flooring it but it doesnt its only wheen rolling off throttle when moving slowish, and im not driving it near 0bar boost either i stay about -0.3 - 0.5

Is this normal?

 

[andeep]

What's your spec?

 

[Fruitbooter]

3" system with Decat
Mushroom Filter
BOV

Thats it engine wise...

 

[tooley]

mine pops and bangs loads its fine dont worry mine runs rich thats why.

 

[pegliobaglio]

Mine does this a lot too mate mainly when I come off the throttle and as said when rolling round at snails pace, no idea why it happens I just assumed it was normal. If it helps I have kakimoto full mega racing exhaust with nismo sports cat.mines done it since I bought it .

 

[andeep]

It's the BOV thats causing the engine to overfuel.

Nothing to worry about mate.

 

[Fruitbooter]

Cheers!

I do like it though, Ive been trying to figure out how to get it to do the loud pops but I think its just by chance tbh lol

 

[craig8585]

Mine pops and bangs on 0% throttle around 2000rpm when slowing. Sometimes it burbles but other times it lets an almighty bang go. Makes me cringe sometimes when you don't want it to do it!

 

[mrpham]

Yeah it's probably your BOV not venting, do you get a flutter/dove sort of sound? It could be because your BOV spring is tight and not opening up on low boost/pressure.

When the BOV doesn't open up, the air is forced backwards through the system and so it passes the AFM which the computer reads and injects more fuel. Therefore you get the little popping noises

 

[craig8585]

You get it with the recirc valves too, but not on gearchange like the VTA valves. The low rpm burbling will be the same with any valve.

 

[hendo]

Yeah like every one that has bolt-on mods mine does it to, although I found mine to pop back with the deep boom less the tighter I wound my BOV.

 

[LuPix_S15]

I had loads of pops with Blitz BOV mounted on the hotpipe plus Kakimoto Full Mega N1 exhaust when I first had the car


Now she's all quiet (since getting HKS Silent + SSQV BOV) except for the insane BANG BANG when I hit the limiter drifting etc due to the overfuelling since remap etc

 

[Fruitbooter]

Now she's all quiet (since getting HKS Silent + SSQV BOV)

She might not sound like WW3 James but urs is far from quiet haha

Spose its down to how you drive it though really.

 

[andeep]

Spose its down to how you drive it though really.

Exactly, but as with Craig mine likes to bang for no reason as well!

 

[tooley]

Its because unburnt fuel is in the exhaust and it somtimes ignights. as lng as it dosent pop and bang when your on throttle (Bar limiter) then is ok. Mine constantly pops on over-run i love it

 

[LuPix_S15]

Yeah I was all for getting the Bee-R limiter until I saw what it can do to your engine, gaskets, turbo eeeeeeeeek!!!!!! :down:

 

[Jay]

the reason this happens at low revs is simply that these cars tend to overfuel at low revs and lean out the higher up the rev range you go. my car has been custom mapped this way, and i assume others are also mapped this way. i get lots of pops and burbles at 2.5k and under but none or rarely above 3k.

i dont know why its better to be running rich at low rpm and lean out higher up, but was told this is the way its done.

 

[Darren_S15]

Yeah pops and bangs quite normal, my car burbles along to itself while slowing down in gear, sounds great.

It's so much better to run rich than lean, I believe the excess fuel helps cool things down slightly.

But run to rich and you will start to damage the piston rings and such, so I have been told.

Pop pop bang

 

[Adam L]

It's the air mass meter recalculating the air in the system when the throttle is closed, so it compensates by adding extra fuel as it thinks the car is drawing in the air. You won't get those pops and bangs with a map sensor.