Jump to content
SAU Community

Recommended Posts

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?

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.

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.

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...

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.

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

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


  • Similar Content

  • Latest Posts

    • My guesstimate, with no real numbers to back it up, is it won't effect it greatly at all.its not a huge change in position, and I can't see the air flow changing from in turbulence that much based on distance, and what's in front of it. Johnny and Brad may have some more numbers to share from experience though.
    • Which solenoid? Why was it changed? Again, why was this done? ...well, these wear..but ultimately, why was it changed? Did you reset the idle voltage level after fitment? I'm just a tad confused ~ the flash code doesn't allude to these items being faulty, so in my mind the only reason to change these things, would be some drive-ability issue....and if that's the case, what was the problem? Those questions aside, check if the dropping resistor is OK ...should be 11~14 ohms (TCU doesn't throw a flash code for this) ~ also, these TCU designs have full time power (to keep fault code RAM alive), and I think that'll throw a logic code (as opposed to the 10 hardware codes), if that power is missing (or the ram has gone bad in the TCU, which you can check..but that's another story here perhaps).
    • Question for people who "know stuff" I am looking at doing the new intake like the one in the picture (the pictured is designed for the OEM TB and intake plenum), this design has the filter behind the front bar, but, the filter sits where the OEM duct heads into the front bar, and the standard aperture when the OEM ducting is removed allows the filter to pulled back out of the front bar into the engine bay for servicing, a simple blanking plate is used to seal the aperture behind the filter This will require a 45° silicone hose from the TB, like the alloy pipe that is currently there, to another 45° silicone hose to get a straight run to the aperture in the front bar Question: how will it effect the tune if I move the MAF about 100-150mm forward, the red is around where my MAF is currently, and the green would be where it would end up Like this This is the hole the filter goes through  Ends up like this LOL..Cheers    
    • Despite the level up question, actually I do know what that is....it is a pressure sender wire.  So check out around the oil filter for an oil pressure sender, or maybe fuel pressure near the filter or on the engine. Possibly but less likely coolant pressure sensor because they tend to be combined temp/pressure senders if you have one. Could also be brake pressure (in a brake line somewhere pre ABS) but maybe I'm the only one that has that on a skyline.
    • Pull codes via the self-diagnosis procedure. As far as I can tell this is just a sign of transmission issues but not a code unto itself.
×
×
  • Create New...