Help With Exhaust

[bundy_bowler]

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?

[Silvia GTR]

Are all the bolts tight? did you use new gaskets? how big is the exhaust?

[gotRICE?]

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 May 6, 2009 by gotRICE?

[brentos]

I lost responsiveness with my 3.5" exhaust too but gained boost and power up high.

[Silvia GTR]

My bad lol

[STATUS]

brand?

[Kinks]

I lost responsiveness with my 3.5" exhaust too but gained boost and power up high.

Yeah I also feel like it's not so good at low RPM and on light throttle after a full exhaust. Definite gains up top though.

[and3_3]

standard ecu likes back pressure from exhaust is my guess, with my power fc tuned with a straight 3 inch pipe it feels great down low!

[oh to dream]

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.

[EliSun]

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.

[gotRICE?]

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]

it should reach full boost at about 3000rpm.

Won't that depend on whether the stock actuator is still in there?

[brentos]

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?

[gotRICE?]

Try put the stock exhaust back on and see if it helps?

[TALBO]

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

[Flecher]

yea i got same problem when i installed a Trust PE2 3 inch catback system on my r34 gtt~ feel like it's running sluggish than the stock one

[Odium]

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]

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]

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)