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Help With Exhaust

bundy_bowler
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gotRICE? Veteran

gotRICE?

Posted
Posted (edited)
I installed a 3inch cat back the other weekend. After the install i did an ecu reset but the car still runs real sluggish.

It felt a lot more responsive with the old restrictive exhaust on.

Can someone please give me some help?

Seems clear? :)

Bit wierd, if anything it should be making a tad more boost and run better.

Edited by gotRICE?
oh to dream Contributor

oh to dream

Posted
Posted

i just installed a 3" dump pipe and cat to go with the rest of my 3" exhaust using the standard ecu. car feels a tonne smoother throughout the whole rev range and air filter is heaps noisier below 3000rpm because of the increased flow and the turbo being able to spool up sooner. you should definitely not be feeling sluggish. not sure about diagnostic though.

gotRICE? Veteran

gotRICE?

Posted
Posted
Take your car for a quick test drive and look at the factory boost meter.

it should reach full boost at about 3000rpm.

it may sound silly, but check your exhaust manifold, you may have a leak.

Should come on bit sooner than that.. mine makes 10psi by 2700.

Although with full exhaust.. not just cat back.

TALBO Grand Master

TALBO

Posted
Posted
mine doesn't make full boost, 10psi until 5,000 RPM. Is there a problem? Could 3.5" be causing back flow problems in my case?

Afaik, not a problem unless the actuator has been modded...

http://www.skylinesaustralia.com/forums/HO...ost-t42895.html

  • 2 months later...
Odium Grand Master

Odium

Posted
Posted

Strange... Turbo car likes a freeflowing exhaust after the turbo.... engine gets its backpressure from the turbo.... Big exhaust in a N/A car and you don't have enough backpressure + exhaust speeds are too low and it'll work against you. Correct? (very simplified obviously)

I bought my GTS-T with a 3.5" catback on it, got it switched to a stocky for EPA test and it felt so restricted.... bout the same low down, but high range and it struggled.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Strange... Turbo car likes a freeflowing exhaust after the turbo.... engine gets its backpressure from the turbo.... Big exhaust in a N/A car and you don't have enough backpressure + exhaust speeds are too low and it'll work against you. Correct? (very simplified obviously)

Not correct.

Most people with N/A's put exhausts on and don't tune.

I had a twin 2.25" exhaust on a V8 years ago - loved it

mad082 Grand Master

mad082

Posted
Posted
I installed a 3inch cat back the other weekend. After the install i did an ecu reset but the car still runs real sluggish.

It felt a lot more responsive with the old restrictive exhaust on.

Can someone please give me some help?

i would check the dump pipe. when removing or installing the new exhaust you may have twisted the dump pipe a bit (possibly when trying to undo the bolts on the cat) and it may be causing the wastegate flap to foul slightly and not close properly.

mine doesn't make full boost, 10psi until 5,000 RPM. Is there a problem? Could 3.5" be causing back flow problems in my case?

definately a problem. i had a 3.5" exhaust with stock ecu and was making 12psi by under 3000rpm. may be an issue with your boost controller (i also had an issue with a boost controller causing boost to come on very late. it wasn't releasing the pressure between the controller and the wastegate when you lifted off so when you changed gears the wastegate would still be open, and on a few occasions it was open so far at 5000rpm i was only just starting to make boost)

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