Dump Pipe Problems/issues

[Haysey]

Hey all,

after buying a 3" dump pipe (basically just jap, but 2nd hand) my mechanics and i installed it yesterday.... i had a stock down pipe and a slightly larger front pipe, highflow cat, full exhaust from there back....

Anyways been driving it the last few days, and its alot more responsive off boost, exhaust a tad louder/different note(not alot) and it goes a bit harder in the higher rev range...

Anyways, when spooling up, it feels like an absolute nugget, it wont hit full boost(11psi) untill 4000rpmish, spools alot longer, and generally dosent have that low down punchyness that it used to have.....

The car used to hit full boost by 3000rpm and would absolutely rocket from low revs (although choke up high)....

Im rather annoyed (as you get when car isnt right) and im scanning my brain to figure wat the problem is, took it for a drive tonight, after resetting the computer, farken cold night and 100octane, the car SHOULD rocket but it feels like a warm summers night with shit petrol....

Now as for the problem, i cant see any exhaust leaks, the only thing i think it could be is possibly the O2 sensor, maybe got a knock, or dosent like being back in there (didnt clean it just chucked it back in) other than that maybe another computer issue or maybe im being totally wrong and this is how the car should feel/drive. but if it stays like this the stock downpipe is going back in....

So please all, give me some ideas, comments, problems, anything that will help me sort out this issue......

Thanks

Ed

[MANWHORE]

Hey

o2 sensor is only used for cruise. You can disconnect it if you like, it won't affect it when you floor it.

full boost by 3000rpm. are you sure? My rb25 hits full boost at like 3000rpm. On my friend's r32, it used to hit 10 psi at about 4000+rpm.

Just fitting the dump definitely would not make it slower. If you compare it to the stock dump, it really opens up the exhaust.

[Haysey]

Hey

o2 sensor is only used for cruise. You can disconnect it if you like, it won't affect it when you floor it.

full boost by 3000rpm. are you sure? My rb25 hits full boost at like 3000rpm. On my friend's r32, it used to hit 10 psi at about 4000+rpm.

Just fitting the dump definitely would not make it slower. If you compare it to the stock dump, it really opens up the exhaust.

hey man, no problems with the strut brace

it definately feels laggier for some reason, it used to hit fill boost alot sooner than it does now, either that or my guage is reading wrong, ill check that out tomorrow, just thought id get some ideas and opinions.....

The car feels a whole lot more responsive off boost its just this boosting issue that is annoying me... i hope its not just me being neurotic

[MANWHORE]

May sound silly, but is it still running the same boost?

[Haysey]

yeah, ran a bit higher whilst the computer was learning, but sorted itself out in <1km.....

still at 11psi.....

ill have a look and tinker tomorrow....

any more ideas?

[RANDY]

Sounds like a small boost leak?

One that only opens up when the pressure builds. It would explain why your off-boost and idle is still fine.

[Haysey]

i cant see how there would be, we didnt touch anything except the dump pipe....

Ill reset the computer now, have a look and see if anything looks farked....

any more ideas?

[Sydneykid]

Hey all,

after buying a 3" dump pipe (basically just jap, but 2nd hand) my mechanics and i installed it yesterday.... i had a stock down pipe and a slightly larger front pipe, highflow cat, full exhaust from there back....

Anyways been driving it the last few days, and its alot more responsive off boost, exhaust a tad louder/different note(not alot) and it goes a bit harder in the higher rev range...

Anyways, when spooling up, it feels like an absolute nugget, it wont hit full boost(11psi) untill 4000rpmish, spools alot longer, and generally dosent have that low down punchyness that it used to have.....

The car used to hit full boost by 3000rpm and would absolutely rocket from low revs (although choke up high)....

Im rather annoyed (as you get when car isnt right) and im scanning my brain to figure wat the problem is, took it for a drive tonight, after resetting the computer, farken cold night and 100octane, the car SHOULD rocket but it feels like a warm summers night with shit petrol....

Now as for the problem, i cant see any exhaust leaks, the only thing i think it could be is possibly the O2 sensor, maybe got a knock, or dosent like being back in there (didnt clean it just chucked it back in) other than that maybe another computer issue or maybe im being totally wrong and this is how the car should feel/drive. but if it stays like this the stock downpipe is going back in....

So please all, give me some ideas, comments, problems, anything that will help me sort out this issue......

Thanks

Ed

Sounds to me like you are getting a bit of R&R mapping. It is quite common for that to occur as the boost is building, because the airflow increases much faster than the ECU is mapped for. Hence it throws in a bit more fuel and retards the ignition. This goes away once the boost is stable and the ECU is seeing more normal rpm and airflow increases. You can see it all the time on the dyno graphs as a power dip, flattening off in the curve.

Do you have any tuning capability? SAFC, Power FC, rechip? That will enable you to fix it.

I am also confused by your use of the terms “dump pipe”, “down pipe” and “front pipe”. The standard configuration goes;

Dump pipe --> engine pipe --> cat --> cat back exhaust

Many of common front stages of the exhaust combine the dump pipe and the engine pipe into once piece. Save weight, a couple of flanges, nuts, bolts and a gasket.

cheers

Edited July 24, 2006 by Sydneykid

[Tangles]

Ive got the same dump pipe - is beautiful and nice and responsive.

But - the dump pipe connecting to the turbo, the welds - they are not that great. Pretty poor in fact, in my opinion. But for $200 you cant complain too much.

I bet youve got a leak there - take it off and reweld around the edges. Costs bugger all. Fixes up the welds around that area and can then be guaranteed it aint leaking from there!

[Links]

Would agree with SK.. maybe it's getting a higer rate of flow.. R&R'ing.. which will of course feel slower to you..

See how you go easing it onto boost.. Also - I don't see how the boost could change e.g. yeah, ran a bit higher whilst the computer was learning, but sorted itself out in <1km..... as I don't believe that the boost would be controlled by the computer in any way..

Might be wrong.. maybe it's time for a Dr. Drift ECU tune!!

[Haysey]

Sounds to me like you are getting a bit of R&R mapping. It is quite common for that to occur as the boost is building, because the airflow increases much faster than the ECU is mapped for. Hence it throws in a bit more fuel and retards the ignition. This goes away once the boost is stable and the ECU is seeing more normal rpm and airflow increases. You can see it all the time on the dyno graphs as a power dip, flattening off in the curve.

Do you have any tuning capability? SAFC, Power FC, rechip? That will enable you to fix it.

I am also confused by your use of the terms “dump pipe”, “down pipe” and “front pipe”. The standard configuration goes;

Dump pipe --> engine pipe --> cat --> cat back exhaust

Many of common front stages of the exhaust combine the dump pipe and the engine pipe into once piece. Save weight, a couple of flanges, nuts, bolts and a gasket.

cheers

It definately feels like its retarding in some way, ive got an aftermarket chip in the car that was a copy of a specifically tuned RB20 chip (exhaust, cooler, more boost new maps), bought it off another forum member, its got new ignition, fuel maps, higher rev limit, no speed cut and a few other small tweeks, when i changed it from stock to the aftermarket chip there was a HUGE difference, car revved more freely, more power etc etc. Not a problem with it since ive had it.

What i meant was down pipe= straight from turbo to the "front pipe" and these 2 pipes were replaced with the "dump pipe"

Tangles- it was 2nd hand, no signs of leakage....

Links - Whilst the ecu is relearning its maps, getting all the settings etc it boosts higher (13psi) but goes like an absolute nugget once its relearnt it goes back to normal....

Damn if this is going to be a costly exercise, ill just stick the stock dump and aftermarket engine pipe back on, went alot harder than it does atm......

Ive reset the computer again, but havent run it in, so ill do that tonight when i get home..

[Sydneykid]

It definately feels like its retarding in some way, ive got an aftermarket chip in the car that was a copy of a specifically tuned RB20 chip (exhaust, cooler, more boost new maps), bought it off another forum member, its got new ignition, fuel maps, higher rev limit, no speed cut and a few other small tweeks, when i changed it from stock to the aftermarket chip there was a HUGE difference, car revved more freely, more power etc etc. Not a problem with it since ive had it.

What i meant was down pipe= straight from turbo to the "front pipe" and these 2 pipes were replaced with the "dump pipe"

Tangles- it was 2nd hand, no signs of leakage....

Links - Whilst the ecu is relearning its maps, getting all the settings etc it boosts higher (13psi) but goes like an absolute nugget once its relearnt it goes back to normal....

Damn if this is going to be a costly exercise, ill just stick the stock dump and aftermarket engine pipe back on, went alot harder than it does atm......

Ive reset the computer again, but havent run it in, so ill do that tonight when i get home..

At the moment you have a guesswork tune in there. You have now done enough mods so that guesswork is no longer good enough. First job, spend $50 (or so) and get yourself along to your local dyno. You want 4 graphs from the one power run, being power, torque, A/F ratio and boost.

Post them up and we can give an opinion. If it needs a retune, $200 or so should cover it.

cheers

Edited July 24, 2006 by Sydneykid

[TurboX]

That downpipe sounds like the one I got that definately improved response etc AFTER I had it rewelded and ported extensivly because of the crap construction. The way they inserted the 3" reshaped pipe into the flange left a lot to be desired and I am sure would have impeded and disrupted flow.

Anyway LISTEN to the voice of reason!! (SK)

[Haysey]

At the moment you have a guesswork tune in there. You have now done enough mods so that guesswork is no longer good enough. First job, spend $50 (or so) and get yourself along to your local dyno. You want 4 graphs from the one power run, being power, torque, A/F ratio and boost.

Post them up and we can give an opinion. If it needs a retune, $200 or so should cover it.

cheers

aiight, whos the best blokes in sydney for the job?

[Haysey]

Slight update, took her for a drive the other night. it wont even spin 2nd in the wet, used to do it as soon as boost came on.

When the engine is cold, it drives like it used to (boosing early) but when she warms up she definately becomes slower,

Im going to try the stock computer chip and see if that adapts to the new dump pipe better, if not the stock engine pipe and larger front pipe is going back on untill funds let me get a cooler and a proper tune...

Ed