Leaking Boost Charge

[R338OY]

My r33 is losing boost throughout the rev range . Stock turbo & cooler.

All clamping and piping is OK.

Could it be a tiny air leak i can't obviously see?

Or could it be my wastegate? Might it open earlier than its meant to? I'm no expert on wastegates so could anyone suggest how to check it?

Any diagnostic tests i can do?

Edited December 5, 2007 by R338OY

[Fry_33]

It could be a blocked CAT, it won't be too bad at low revs but as you build revs and boost there is more exhaust gases and if it's blocked becomes a huge restriction and won't flow the required amount of gases to allow the higher boost levels.

[Simmo1985]

My car was doing this too. I took it to the mechanic this morning, mechanic took it for a drive.. comes back and asks me to go with him.. wouldn't you fkn know it - the car isn't doing it anymore.. I left the mechanics this morning without paying anything, although I think I would rather had to have paid for something broken instead of asking them to look at a car with nothing wrong with it.. lol. Ah well..

[R338OY]

It could be a blocked CAT, it won't be too bad at low revs but as you build revs and boost there is more exhaust gases and if it's blocked becomes a huge restriction and won't flow the required amount of gases to allow the higher boost levels.

My cat could be an issue. I'm pretty sure everything is FINE on my car which is why i'm confused. I noticed a week ago my exhaust was full of rust holes and sh!t, so i patched them up (but it has partially broken the putty off). Car drives little better, though sounds much better. The rust was from the resonator back, cat was fine.

Otherwise i'd have to pop off the exhaust to figure it out.

Could it be coming from under the hood? The wastegate?

Any tests i can do?

[Fry_33]

If your exhaust is a bit suspect then maybe you could start taking pieces off it starting at the back. ie. take the rear muffler section off and go for a quick drive and see if you can acheive full boost. If you can then the muffler is probably cactus, if not, take the next section out.

What psi was your car set to and getting to previously and what is it acheiving now?

Edited October 2, 2007 by Fry_33

[swanny180]

More info needed mate.

Are you running any form of boost control? If so what? Also, what is it set at?

What boost does your car usually run?

What is it hitting now?

How does it reach that boost? Does it come on like normal then stop climbing at a lower boost pressure?

Or is it more sluggish to reach a given boost pressure?

Knowing these answers should help eliminate a few possible causes (eg boost controller, wastegate, stock solenoid etc)

[Syphon]

Interesting that this topic has just come up as I was searching for some answers to this last night.

My brother currently has a S1 33 gts-t which has a similiar issue. It only acheives 5psi boost over the whole rev range. I have modded the std boost solenoid aswell and still 5psi all day. No bleed valve, nothing. All standard aside from cat back exhaust. Not sure on condition of cat convertor but wouldnt think a slightly blocked cat would stop it acheiving 7-8psi of boost. No leaks on the cooler piping that I can find this far. Doesn't appear to be leaking although he has mentioned that the idle stumbles around occasionally which makes me think it has a vacuam leak somewhere. Also only other piece of information is that the std boost gauge in the dash doesnt read any positive pressure. Only reads up to 0, and never goes any higher.

I am starting to lean towards either a faulty boost solenoid, or leaks in the intake system somewhere. I presume that the standard wastegate allows approx. 5psi and the solenoid bleeds off a few psi once your over 4500-5000rpm or however it works, achieving full boost.

[R338OY]

If your exhaust is a bit suspect then maybe you could start taking pieces off it starting at the back. ie. take the rear muffler section off and go for a quick drive and see if you can acheive full boost. If you can then the muffler is probably cactus, if not, take the next section out.

What psi was your car set to and getting to previously and what is it acheiving now?

Yeh still iffy about the exhaust. It was running fine with a manual boost controller @ 11psi. Lots of power and no dropping of boost.

I removed and cleaned my side mount intercooler, replaced it and was fine for a week. Actually had to turn down the MBC because the clean side mount flowed an extra pound!

Now it can reach 10-11psi, but only for a second and drops down about 3psi. Only time i get power is when i mash the throttle and the leak isn't as obvious. Even then it doesn't hit as hard as before the leak.

More info needed mate.

Are you running any form of boost control? If so what? Also, what is it set at?

What boost does your car usually run?

What is it hitting now?

How does it reach that boost? Does it come on like normal then stop climbing at a lower boost pressure?

Or is it more sluggish to reach a given boost pressure?

Knowing these answers should help eliminate a few possible causes (eg boost controller, wastegate, stock solenoid etc)

Yeh man. boost control, as above. I never go above 11psi, usually keep it 10-11psi.

Now it will reach 10psi but takes longer to do it and won't sustain it.

Leak is most noticable at low rpm, when there isn't as much charge. I can visibly see my boost gauge needle sink after it climbs from -0.5 up to 0 BAR. Past 0 BAR it will climb with the revs, by that pressure i'm doing 3500+. Even the motor isn't howling like it was.

So yeh i'm still getting boost, but power is being noticably lost.

I'm taking a stab at the intake side of the engine is leaking.

[R338OY]

Ok i've taken off the boost controller, checked if the ball bearing was stuck (was fine) and put it back. I also checked the intercooler plumbing and tugged around the piping to see if there was too much movement (fine) and all the clamps where on (fine).

I took it for a thrash and i noticed it HOLDS boost, it was running 11psi and held it, so thats good.

BUT it isn't as responsive low down (it lags a little more) and used to launch when i floored it, but doesn't 'launch' anymore. It also doesn't climb the rev-band as fast as before. It really gives up at 6000rpm. The (factory) wastegate also isn't as loud; it doesn't spit as much air as before.

ONE MORE THING - tracing this problem, i FIRST noticed it when i went on an SAU cruise and i was gunning it repeatedly. Toward the end of the day i noticed the boost wasn't KICKING IN and it was sluggish, and appeared to be leaking boost.

Have i damaged something? Or is there something i'm missing?

[Simmo1985]

If you've damaged something it's probably just a piece of piping or something that's split/cracked or come less under all the constant pressure. That mixed with the heat of the engine bay.. That'd be my guess anyway.

[R338OY]

If you've damaged something it's probably just a piece of piping or something that's split/cracked or come less under all the constant pressure. That mixed with the heat of the engine bay.. That'd be my guess anyway.

Possibly too much pressure i'd say. I have given the stockkie turb a whooping at times

Well i raced a V6 Commodore up Parramatta Rd and the M4 yesterday (going west from Sydney) and yes i molested it with my 33 but i would usually have pulled away easier

I did my bit guys, don't worry, at the lights where you turn off Parra Rd and it merges into the M4 i asked if his car was worked and he replied, "I was thinking about getting a Skyline mate...they go haaaaarrrrd!"

"Yes, they do ", I replied.

And then all he saw was four round tail lights zoom into the distance...

Edited October 13, 2007 by R338OY

[uraah]

might be a long shot but have u checked ur gaskets cos i had simular prob with my old silvia turned out to be a leaking turbo gasket

[Simmo1985]

My problem is still occuring (similar to yours, as posted earlier). It came good for a day, then back to boost dropping off.

I think my problems a gasket problem.. makes a high pitch whistling sound sometimes when under heavy load, apparently that means gasket. No idea how much a gasket is or how hard it is to do yet.. anyone know? I'm guessing it's either the turbo, exhaust or intake manifold gasket?

[R338OY]

might be a long shot but have u checked ur gaskets cos i had simular prob with my old silvia turned out to be a leaking turbo gasket

Never thought of that one. I'll check that, cause i have a feeling its the turbo which is the problem and not the piping or hosing.

I'll take a look at the turbo and see if the gaskets are ok.

Thanks for the idea

[R338OY]

UPDATE:

A mechanic inspected my R33 and found at least one stud missing from my exhaust manifold, resulting in pressure loss where the gases meet the turbo exhaust housing.

He's removing the lot as we speak and will replace the manifold gasket and studs. He also inspected the turbo and found no play with the compressor wheel. Oh and he added that it's not a factory turbo, it has factory housing but uses a ball-bearing system to spin TWO compressor wheels . Not sure about the impellor on the exhaust side. I'm assuming it's no longer ceramic though.

If any of you guys are leaking boost consider checking the exh. manifold studs for breakages.

Cheers.