Ridiculously loud exhaust popping (200sx)
 

Hello,

Not sure if anyone can help but here goes. My mate has a 1994 S14 JDM Silvia (200sx) with full 3" exhaust, Sard BOV and Apexi Induction kit plus a bleed valve which he says is set at 1bar. I went out in it last weekend and the exhaust pops/bangs it produces are unbeleivable. I mean my old MY99 Impreza with full decat and BOV popped and flamed a bit with the odd bang on overun but this bangs like a shotgun sometimes 4 or 5 times on overun. Really really loud like a gunshot. The car seems to run and pull well but I cant beleive this is normal popping from the exhaust as its so loud and frequent. Anyone got any thoughts? Could something else be causing or contributing to this?

Cheers

Mike

Yes, he's being shot at by his neighbours who are pi$$ed off at the noise coming from his chavvy motor. :thumb:

HTH

Possible but in this case I don't beleive so ;) Not a 200SX fan then :wonder:

Love the 200sx, but anyone whose motor sounds like his a shotgun has chavved it up! ;)

solberg, mcrae, hirvonan, grondholm.. to name but a few :D

mine does it :D, but i always take it steady on the estate, a to let the engine cool down or warm up and b not to p'ss off whole estate lol

Thats the thing though he hasn't. I know some people say VTA BOV's are chav but even that aside it just has a full exhaust and an Apexi Ind kit and Veilside wheels. Hardly chav. I had similar mods on both Imprezas I have had and on my current Evo its just on his Silvia it seems to have created this firecracking soundtrack and thought someone may have an explaination.

Probably running lean, especially if its had a full exhaust and induction kit fitted IMO.

If it were running lean it wouldn't be popping and banging ;)

was gonna say wont be running lean unless theres major fueling issues going on and more is ending up out exhaust instead of in the piston lol

all the poping and banging is unburnt fuel in the exhaust igniting

Needs a remap IMO, will make it run better, faster and more reliable as it matches the mods to the ECU. Mate had an S14a 200SX and done very similar mods but added a FMIC, popped and banged much more than my decatted 02 WRX. Got a mapped Apexi ECU and it ran much better, used less fuel and was much quicker than before!! Still got the odd pop and bang so he was happy :lol1:

ive had 4 200sx's and they have all done it the VTA dump valve causes it to overfuel on gear changes or lift off. if he doesnt like it visit www.h-dev.co.uk as this guy is fantastic at mapping them and will stop it doing it :thumb:

The s14 runs a very rich map when the airflow starts to increase, ie the boost is wanged up:thumb: thus there will be a fair old commotion from the rear especially if the stock re-circ has been swapped or had its hole blocked to stop it leaking and the cats are gone. Also the stock wingmount could be leeking a tad, making it overfuel even more.
Not really anything to worry about though, but if its becomming annoying then swap the DV back to standard and it will quieten down a little.
It will fairly shift at that level of tune as its going to be circa 260-270hp even without a remap, visit the sxoc for a bit more info if he is worried.

Popping and banging isn't always unburnt fuel in the exhaust system.

Unburnt fuel will travel through the exhaust, and without any air it will just vapourise by the time it reaches the back box. However, add oxygen to unburnt fuel and it will product the pops and bangs.

My 205 sounded like it had an anti lag kit on, until my mapper sorted the throttle body sync and the popping went.

The bodies were slightly open on overrun allowing too much air through (lean), the air was working backwards and mixing with any unburnt fuel from a power run (rich) and causing the issue. :)

So it can come from running lean and rich in a way.

It can also come from a hole in the exhaust system, or the timing/fuelling being out.

So, davegtt isn't wrong when he says it may be lean. :)

I have this problem, not from the car though.....

Its is Chav though, to any normal punter, ok for us lot on here or similar bbs's it is drifter chic but the general pblic dont differentiate between a drift sec 200 SX with 15 grans worth of mods and a Nova with a bit of old drainpipe and neons.

its the DUMP VALVE wich causes it as been told by my m8 whos sx bangs usually when changing gear at certain revs with little boost he has an apexi exhaust only one silencer very very loud . dont know which valve he has but its running 270 at the fly on standard ecu with a dawes device controlling boost pressure think its 18psi and it goes great just bloody loud and bangs all the time really pisses my neighbours off when i get picked up for work in the morning at 6am:nono: the exhaust heats up and ignites the fuel in the exhaust.hes running a standard clutch too. been told the ecu can increase the fuelling for extra boost pressure up to a certain amount so your safe.
also he has a cone filter which makes a awesome noise when changing gear he told me its not the wastegate chatter as i suspected as the noise was coming from the left hand side of the engine bay where the cone sits and is the air rushing back out the filter so he says:wonder:
how do you like they apples?

Unfortunately while the 200SX SR20DET powered is a great car, with Stage 1 mods it does this like a muppet!!! Stock map runs WELL rich at higher rpm - remap helps and also generates more high end power :D

leaking header or somewhere in exhaust system

i had a sx for three years and mine did it too, most do they have alot of unburnt fuel when youve done some mods to them, a remap will sort it out
some people dont bother case they like the popping:freak3:
very rally :D

It's the SARD blow off valve that's the problem, it's a vent to atmosphere one, which fools the airflow meter when it dumps, this causes them to overfuel and makes them pop & bang excessively.

Trust me... ;)