stig wrx

hi y,all, newb here looking for advice on my 96 wrx import,
when i change gear there is loud pop noise out of exhaust (unburnt fuel i assume)?, sounds good i think! but wondering if its bad for engine? it mostly does it when changing gear slowly, i have blitz dump valve,de cat,
has any one else had this and whats your opinion guys?

cheers,

Wurzel

iTrader: (1)

I had this when my VTA dump valve was not man enough for the job so I binned it and put the original back on, problem solved instantly. It now does it because my lambda sensor is kaput, sounds more like antilag though, hoping new lambda sensor will cure the issue though.

jamie_l

mine does it too, also have dv and decat, just be the unburnt fuel burning off due to the afm telling the ecu how much to put through then when you change gear the air that has passed through goes out the dv and the extra fuel goes pop, dunno if bad for engine

stig wrx

cheers guys, might try puttin standard dv on see wot happens, wurzel how many lambda sensors are there? the one on downpipe from turbo is not connected on mine but im sure there is another one at manifold?(ill need to check) im thinkin this could have something to do with it but not too sure,
jamie its been like this for ages and no probs so hopefully its cool!!

Wurzel

iTrader: (1)

I have a MY00 classic and I have one in my downpipe. No idea how many you should have.

Why is your not connected??

do you have crap fuely economy aswell? I noticed mine was not working as my fuel economy went **** up, there was a smell of petrol/exhaust mix all the time and it started sounding like antilag was switched on when changing down gears.

jamie_l

standard recirc dv would sort it as the air goes back into the inlet keeping the air/fuel ratio right so wont be overfuelling

stig wrx

when i bought car off trader exhaust went (downpipe) so they fitted used one,may have come off diffrent car,cant be sure. have looked all around erea for sensor plug but nothing,so thinkin some had 2(post and pre turbo) and some didnt,
now u mention it my misses kepps saying she can smell fuel, fuel economy i havnt noticed as its always been a fuel dump anyways!
im gonnie check up on the lambda sensor issue maybey other one is chucking it
cheers for your time

Wurzel

iTrader: (1)

according to the subaru schematics for my car there should be one in the exhaust manifold where the uppipe joins the manifold. However I have never had one fitted there, I know this because I changed the manifold from the OEM one to a Gruppe S. Also the cable harness from the car is not long enough to reach if the sensor was in the manifold, plus all the times I have had the car worked on by Bob Rawle he has gone to the downpipe and not the manifold to disconnect the lambda sensor so I assume it should be in the downpipe by default. I would get it checked if I was you, you never know.

stig wrx

i "think" the one at the manifold is connected on mine as i know the defo needs to be one connected somewhere but would assume at downpipe also!, strange eh, ill get it checked out
cheers

mr_D

iTrader: (12)

im sure this damages engine. as will coat the bores and may cause the piston to melt. ?????

i know i will over fuel if i disconnect my speedo cable and i get some almighty bangs that scare even me. (funny when passing pedestrians). but defo not good for car. if you got a vta dv and its adjustable then tighten it a bit and see if this helps. if not try and clean the maf or look for air leaks.

stig wrx

ill try tightenin up valve as the bolt is screwed quite far out i think, checked 4 air leaks,
iv got diagnostic computer and its not showing any faults with maf or anything, it did come up couple of months ago throttle position sensor but cleared the fault and not showed any since, so assumed its not leaks or sensors, ill also check this out

tweaks

iTrader: (7)

mine pops all the time when changing gear,just mapped slightly rich(this is not a bad thing)also no lamda in decat downpipe its in manifold.i'm running no valves(dv or recirc).
hope this helps.

p.s
it used to do it when it was standard with decat,standard ecu etc....

m@t STImulation

iTrader: (3)

as above i have no vent valves (dv or rec) i also have no cats :-) mine does it at low speeds as above over fuling i think. better to be rich than lean!

stig wrx

cheers guys its put my mind to rest now
beers on me!

TurboAndy

iTrader: (1)

My old scooby was mapped by Andy Forrest, (one of if not the best engine mappers in the uk.

My scooby also did this popping and banging, It does NOT damage the engine.

He said all it was, was unburnt fuel being ignited in the exhaust.

Also some people have this added when they have there car re-mapped and mappers would not do this if it was going to damage your engine.

Hope this puts your mind at rest.
Hope this puts your mind at rest

mr_D

iTrader: (12)

over fueling will not be good in the long run.

in small doeses its ok if car has been mapped for it. but if the car does it all the time constantly then it cant be doing the car any good.

general overfuelling at low gears with big bangs means alot of over fueling. ! this aint good. otherwise people like my self wouldnt bother getting a remap after the mods. people are always complaining about how you will over fuel and things. why worry if it aint an issue!!

gaz c

had my bug maped at the best place of all (scoobyclinic). i asked pat hoo maped it to put extra few pops and bangs in there. i can make the car pop and bang on command!!! which can be fun at times. as someone has said if the mappers thought this would damage things then they wouldnt do it..

TypeR6000

Nothing to worry about with a little over fuelling. Running lean would be alot worse.

stig wrx

cool, that does put my mind at ease
cheers, well off i "pop" then

shawn r

iTrader: (3)

mine goes pop a few times and have been told that there are blue flashes rather than orange ones from the exhaust,
whats the difference? (other than colour lol)

stevebt

iTrader: (8)

I would rather the pops and bangs were gone from my car but I think it goes with the territory. Mine pops and bangs constantly in any gear and anytime on slight decellaration. I have to be really carefull when police are behind me as it takes more effort to stop it.

burbling1

iTrader: (1)

I believe you only have one lamba sensor and thats on the manifold, the wire on the downpipe is a cat on fire sensor if you have a decat this will be unplugged. As for you pops during gear change this is due to the vta as stated. The maf sensor has seen x amount of air get sucked in so puts fuel in to match but the vta dumps the air so too much fuel. As long as it only does it during gearchange I dont think you will have a problem(i dont on mine) but others will start talking about borewash and contaminating your oil and the likes.
If it worries you enough put the standard recirc back on.

stig wrx

iv checked and sensor on manifold is plugged in and only poppin on gearchange so happy days,
oil not a problem i change it reguarly anyways

Wurzel

iTrader: (1)

Not strictly true, the early classics had the lambda senser in the manifold the later models had it in the downipe between the turbo and the cat, even if you remove the cat you will still need the lambda senseor in the downpipe near the turbo.

lloydee

iTrader: (2)

My car has ecutek and I love the pops and bangs it makes wish they were louder tbh

motorola222

i want pops and bangs!

mine doesnt do any! it has magna flow de-cat and manaflow exhaust the rest is standard so how do i get these "rally" pops and bangs.

oh and btw if it is the "anti-lag" at fault ur gonna have problems due to the pressure it creates in the system ur exhuast wont last longer than 5k miles with it on.

gaz c

[quote=motorola222;8891681]i want pops and bangs!

dee cat it and put a DV on there! you will get some then.

RED2

jgm mapped some pops and bangs into mine, love it but sometimes have to be carefull going past coppers

Black-Hawk

iTrader: (4)

And oldies

scoobydoe

not sure if its bad but it sounds good dont it lol