Hi Guys,

just after a bit of advice. I have a TD06-25G kit, but where I live in New Zealand, we have just implemented very strict db levels... I've had to plumb the dump pipe from the external wastegate back into the exhaust AND downsize the rear section of the exhaust to 2 1/4 inch pipe just to try and meet the db levels.

Problem: Now when the car comes on boost (4000rpm) it coughs, splutters, hesitates, you name it and just plain runs like a pig. Boost is erractic i.e stops at 5psi for a bit and then rushes up to 12psi instead of being smooth. Would this be because of the wastegate being plumbed back in to the exhaust creating turbulence and excess backpressure? Any advice would be greatly appreciated!

 

Need more info;

What mods overall.

1. did it run right before the modifications
2. are you boost controlled (electronic or manual)
3. what wastegate

Can't even guess until we know this

 

Cheers for the reply!

Main mods are:
Greddy TD06-25G Kit
FCon V Pro
Greddy 50mm Wastegate
ARC Intercooler
Mild port
13psi HKS Hiper exhaust

The car was sweet until I drove it outta the Exhaust Shop... so it must have something to do with plumbing the dump pipe back into the exhaust, and maybe the fact that i've had to down-size the rear end of the exhaust - all done at the same time. (there is a Greedy Front pipe off the turbo).

I'm sure this is the reasoning, but just would like to know WHY this has happened, and what do you guys recommend? Should i just no plumb it back in and run the dump pipe to the end of the car? I have lost bucket os power after the exhaust shop fiddled with it!
ARRRRRGGGGHHHH!!!

Cheers guys!

 

If this new law just required a db adjustment, then all you had to do was install a good pre-silencer in your exhaust system. You did not have to change pipe size if the new inspections did not require a visual inspection. If available, Racing Beat makes a decent pre which can knock your db's way down low.

 

It is almost surely running rich from the added backpressure (more backpressure = less flow = richer mixture). See if you can find some less restrictive way to keep under the sound limits, and then re-tune to get the mixture right.

-Max

 

i'd just undo what you did and get a resonated mp ror something. the dump pipe is useless unless at full boost.....and when are you ever gonna be hauling *** when there is a cop around?

 

Thanks guys... i'm going to revert back to my old set-up this weekend... I never knew that increased back pressure makes a car run richer... but now I know! Unfortunately, it still doesn't solve the problem with the db limits though! Oh well.

13b_boost... in regards to your comment, i agree with you, however, the guys in NZ issuing Warrant of Fitnesses tend to check db limits with their "eyes" rather than their ears, so downsizing the pipe was something i had to do to to get my car passed! A smaller pipe size seems to keep them happy.

Cheers once again all.