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Exhaust System On But No Change!

WOG BOY

By WOG BOY,
in General Automotive Discussion

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WOG BOY Community Regular

WOG BOY

Posted
Posted

got my exhaust system on yesterday.....3" turbo back....hi flow cat...etc....anyway....

there seems to be no difference in power....and i still cant get it over 5psi from giving it a boot....

also, i believe that the company i bought the hi flo cat from sent me a s13 cat instead of and r33 cat...would this make any difference to it? like would it be more restrictive?

(the s13 cat has been fitted on my r33.......as i had no other options but to fit it until i can get the company to sort it out....)

so yeah, just wondering why it still hasnt made a difference?

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R338OY Veteran

R338OY

Posted
Posted

Get it inspected. Just a cat-back gave me very noticable gains, and it also allows more boost to be made.

Your exhaust can't be the problem, it's just a long pipe, it must be something else. Only thing i can imagine is the cat isn't new and it's blocking exhaust flow.

Otherwise something else is farked.

redevil Proficient

redevil

Posted
Posted

It won't be your exhaust causing you to get low psi... as stated before most likely a vac leak or actuatur fault.... exhaust system won't affect your max boost mine would hit 7psi when completely stock... i'd say you have a problem elsewhere

**RB2530** Proficient

**RB2530**

Posted
Posted
got my exhaust system on yesterday.....3" turbo back....hi flow cat...etc....anyway....

there seems to be no difference in power....and i still cant get it over 5psi from giving it a boot....

also, i believe that the company i bought the hi flo cat from sent me a s13 cat instead of and r33 cat...would this make any difference to it? like would it be more restrictive?

(the s13 cat has been fitted on my r33.......as i had no other options but to fit it until i can get the company to sort it out....)

so yeah, just wondering why it still hasnt made a difference?

What size is your turbo and what type of wastegate (internal or external) and at what rpm does it acheive 5psi??

(B1) MR_fanny Grand Master

(B1) MR_fanny

Posted
Posted
and i still cant get it over 5psi from giving it a boot....

looks like you had a problem even before you installed the cat + exhaust system. stockers should be runing 7psi and with full exausht sys it should be 9-10psi

model specific generally means cat length and bolt up patterns. its usually a universal hi flow cat with custom flanges welded to fit the model

**RB2530** Proficient

**RB2530**

Posted
Posted
the car is all stock.......except now for the exhaust.....

so, i should take it to a mechanic to see if there is a fault in vac pressure or something? or what should i do?

If your WG spring is broken (inside actuator) that could be it...I can't remember since stock setup is a long time ago for me, but if you can access the rod coming out of the actuator make sure that you can't easily move it in and out of the actuator. If you can then the spring is broken...I don't think this a common failure though but worth checking if you can...5psi sounds like what you what get if the WG is opening too much due to a broken or very weak spring...

Krishy Grand Master

Krishy

Posted
Posted (edited)

interesting that one....but as mentioned above i dont think your exhaust would be causing that problem....to me it sounds like a vac leak or could be worse a manifold gasket leak.....but yes you should be hitting 7psi even if its bone stock.....but also remember that having an exhaust doesnt give you massive amounts of power....and dont expect to have your boost to hit 9-10 psi without winding it up...another word of advice is to check if your stock boost controller is plugged in the right way....a mate of mine had that problem and was only hitting 5psi when he set the boost level for 9psi...

chuck it on the dyno a lot of problems can be found that way

Edited by Krishy
thommo Mentor

thommo

Posted
Posted
Just thought you could also disconnect your wastegate and see what difference this makes...BUT DO NOT DRIVE IT HARD!!! Take it very easy and just lightly pedal it to see if it exceeds 5psi...

dont do this... ^^^

if you're not confident mechanically, take it to someone who knows what they're doing.

**RB2530** Proficient

**RB2530**

Posted
Posted

Yeah ok if you have absolutely no idea what you are doing don't do it...If you decide to, I can't stress enough dont drive it hard!! What should happen if the WG is ok is that you will get a boost spike if too much pedal...That is why I said pedal the car very lightly..This means very light throttle...If the WG spring is weak or broken, the exhaust pressure itself will force WG open and you get only a small rise in boost...

You will hit air flow cut (aka boost cut) before anything significant happens if every thing else is stock...

**RB2530** Proficient

**RB2530**

Posted
Posted
so what should i be looking for and where abouts will i find it.....i think i need to do some DIY tomorrow......so let me know....

Do you know where the boost control solenoid is?? It is mounted near the power steering fluid reservior on the LHS of the engine bay...There should be 2 small hoses going to the solenoid. I think one goes from the solenoid to the intake pipework near the airflow meter. The other goes to a T piece that is connected to the intake pipe that runs toward the throttle body and the other side of the T goes to the WG actuator..If you disconnect the T peice line at the solenoid you have effectively put a big bleed valve in and the boost should increase.

Drive the car very lightly off boost and find a section of road that you can cruise at about 100...in 4th gear gradually open the throttle to see what your boost does...Do it gradually because if you dont and it is the WG actuator that is buggered you will find 15psi or more very quickly and the car will boost cut...

Now if after doing this the boost doesn't change it is not the actuator. If it does change it must be the actuator...Re connect the line to the solenoid and check the actuator...make sure you reconnect all vacuum lines even if the boos increases and the car has more power. It is risky to leave lines disconnected...

Also one of the first things i should have asked is how are you ready boost...from the factory gauge??If so check the gauge is reading accurately...Normally they dont after a while...

WOG BOY Community Regular

WOG BOY

Posted
  • Author
Posted

well i kinda know what ur tlaking about.....

i had a look today and there is a black plug with a black wire and a awhite wire comin out of it over near the AFM on the RHS and there is another....exactly the same plug and wire setup on the LHS near the fuse box.....

the solenoid ur talkin about....its got two pipes...bout 2/3" wide...they are kinda mounted on top of each other.....

eg....

I I

====I I

====I I

I I

====I I

====I I

I I

i might take it to my mechanic friend to see what he can do bout it....i dont have a decent mechanical understanding (as u can see)....so i dont wanna chance anything.....

**RB2530** Proficient

**RB2530**

Posted
Posted

Umm fuse box is on the RHS....on mine anyway...RHS looking from back of car towards front...

Yeah if you are not sure get someone else to look at it..But alway ask them to explain to you what they did/do... I am always one for learning....I am in NSW so I can't recommend anyone for you to go to but I am sure someone can that is more local to you..Good luck...

(OO)SKYLINE(OO) Grand Master

(OO)SKYLINE(OO)

Posted
Posted

Did the R33 GTS-T's come with a boost restrictor that you can remove to gain a SAFE Factory boost increase like the GTR R32's? The Brass Boost restrictor I think its called..?

If so, remove it and you sould get up to 7 psi...

WOG BOY Community Regular

WOG BOY

Posted
  • Author
Posted
Umm fuse box is on the RHS....on mine anyway...RHS looking from back of car towards front...

Yeah if you are not sure get someone else to look at it..But alway ask them to explain to you what they did/do... I am always one for learning....I am in NSW so I can't recommend anyone for you to go to but I am sure someone can that is more local to you..Good luck...

ahh k....i was like RHS...hmm....i was referrin to it as looking at it from the front of the engine bay....

i think i know the wires/plug ur talking about.....its jus enxt to the fuse box......

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