Jump to content
SAU Community

Help With Exhaust

bundy_bowler
 Share

Recommended Posts

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)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      New kid on the block

      By GTSBoy · Posted

      The wiring diagram for the R33 RB25 is freely available, and is essentially the same same as most other RBs (just with differences as to which pin # does which job). To get the ECU to power up, you just need to provide power to the ECCS relay, and have the other power feeds that come in from the top left of the wiring diagram (wrt the ECU) that give perma power to the fuel pump relay, the ECU itself, etc etc, all connected. When you put power on all these it will just come to life. It's pretty clear from the diagram what needs to happen. Just follow the lines from the 12V + supply stuff in the top left over towards the ECU. I've even posted snips of such diagrams (not for vanilla 25, I think for Neo and 26) to various threads here in the last few months, talking about what it takes to get the fuel pump and FPCM up and going. Search these up and they will help get you started on doing the same with the vanilla 25 diagram. Hell, for all I know, I've done the same with that one in years past and have forgotten.
    • Duncan
      New kid on the block

      By Duncan · Posted

      Yep...so unless someone posts up the answer you will need to probe from the ECU connector to the dash plug with a multi meter in continuity mode to trace the wires.  Note the ECU has multiple - and + (and across different key settings - Battery, IGN and Start) and most likely the power is fed from the connector(s) that is normally near the left hand headlight.
    • Songo
      New kid on the block

      By Songo · Posted

      Thanks Duncan, I am actually just trying to get the Rb turning and running with the RB25DET S2 original loom itself  I am just trying to get it going outside the body and not thinking about the S15 or trying to match anything to the S15 loom at all I am only trying to see if anyone has done this and what pin they found to be the ignition trigger and ECU+/- on the dash connector, that's about it. Thanks  
    • iain_ST44GA
      M35 VQ25DET starter motor

      By iain_ST44GA · Posted

      Hi Guys, Does anyone know any aftermarket part numbers for a starter motor to suit the VQ25DET? I can find lots of alternative part number for the VQ35DE, which I assume would fit, but there is a lot of conflicting information out there. Thanks..
    • Murray_Calavera
      R33 GTR running -9 with no tune

      By Murray_Calavera · Posted

      I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
×
×
  • Create New...