boost just keeps increasing

[otto]

the wierd thing is when i set a bleeders on say 10 psi the car will run 10npsi down below but will have creeped to say 14up top. playn with the boost was how i originally discovered the prob.

[Black33]

everything points towards this being your wastegate not able to flow enough, but this isn't likely with a std turbo, unless theres a problem.

You said that the wastegate flap used to catch on the dump but you ground it out and now it doesn't. Are you sure it opens fully. What is the design of the dump like? Do the gases have a clear path to escape or is it opening and forcing the gases to flow against the wall of the dump pipe??

[HoeTrain]

the wierd thing is when i set a  bleeders on say 10 psi the car will run 10npsi down below but will have creeped to say 14up top. playn with the boost was how i originally discovered the prob.

Boost creep, especially on hot days is quite common I think, this is why they invented electroniclly controled valves. RBVS, I must agree with you too.

[blind_elk]

Have you checked the hose that connects to the wastegate for something like a split. A split hose is likely to act like a bleed-off valve, and the higher the boost you put in, the wider the split becomes, and the more boost it bleeds off.

[calvintys]

i have the same problem before while i try to install an aftermarket EBC.... but then i solve the problem because i install it wrong....try to see if all your holes are install in a proper order...

[otto]

all the hoses have been checked and r new. im beginin to think and ebc might be the way to go aswell i just dont wanna fork out the dosh for the thing just yet only to discover ive still got the same prob.

black33, the w/g opens till the little arm on the outsde of turbo runs parallel with the front to back of car im assuming this is fully open. the dump is the same shape as the standard flange and on the inside i have ground out any weld, dags, and irregularities so i guess its flowin pretty good i think the gasses would hit the gate before they hit the wall of the pipe. is it possible that the waste passage could be a little fouled with carbon or sumthing the car has done 80000kms.

[RBVS]

ebc will not fix the problem. if you have tied the wast gate back so it is always fully open how is a ebc going to help. if you realy want to run less boost put the standard dump back on.(restrict the flow) or you could go to the effort of removing the turbo, dine grinding the wast gate out 1 or 2 mm but not to big so the gate doesnt cover the hole, also grind away the angle the exhaust flows though the gate. I wouldnt bother, 10psi is fine you just need to be able to keep it their.

the other thing coul be like you said somthing obstructing the flow though the gate, but 10psi seems normal to me.

[otto]

rbvs, i would be happy to run 10psi if i could get it to come on and stay there right through the revs, i actually wanna run 12 but i cant do that at the moment without it creepin another3-4 psi up top will the ebc be able to hold 10+ as bleeders and regs cant seem to do it.

i tried to add an external spring today. it ran 11 psi but still managed to creep to 14+ psi up top (done the same thing as when i tried a bleeder or reg)

[Jay95R33]

Man - it's the wastegate getting stuck. A bleeder, EBC, or extra springs ain't gunna fix it. Rip the actuator out and test it along with the movement range of the wastegate flap. That's the only way your gunna find out what it is.

J

[otto]

jay95r33, finally got around to runin some compressed air through it, the actuator and wastegate operate really smoothly although the actuator gets to full travel way before the w/g. ie, the w/g itself can rotate around over90 deg whereas the actuator at full trave only rotates it around 40deg. does this sound about right, does anyone know how much travel i should be gettin from my standard actuator?

with the compressed air i didnt have it hooked up to a guage or anything (didnt have one) but being really carful on the button once it cracked its movement was very smooth no binding anywhere.

[sky^rkt]

i am having the exact same problem with my skyline atm, its on stock boost and as revs go up the boost goes to nearly 10psi by the time it gets to the redline, just like ottos, otto when you find out what the problem is please tell me what it is as i have checked everything =]

[Jay95R33]

Otto - that's the problem. If the wastegate isn't opening right up (ie. only 40 degrees), then as the exhaust gasses increase and speed up, it won't be able to flow/bypass enough ehaust gasses to control boost.

Does it look like the actuator or rod has been modified (bent/shortened etc)??

Maybe it's not a stock R33 GTS-t actuator ??

[otto]

jay95r33, im pretty sure its the stock actuator what i dont get is if the actuator can hold/waste enough for 10psi when its normal why does it creep higher than 10 when the bleeders there.

anyhow picked up a rb20 actuator today and gave that a go (still gotta check if it has the same travel as the rb25 actuator). in second gear it was pretty good-held 10 psi crept to a little over 12 by 6000 and had dropped back to a little over 11 by 7000. 3rd gear it held 10 then for everywhere else was about 1psi higher than 2nd gear. this is a improvment over th rb25 actuator but does it sound acceptable/normal??

it seems no matter what happens down low im always gonna run a couple of psi higher up top.

do you guys think an ebc would clean things up from hear or is my problems still elsewhere considering i wanna run a pretty acurate 12psi??

i would have the biggest cry if i forked out the money for one and it didnt help, this problems already come close to reducing me to tears as it is(he he eh)

[Revhead]

The EBC should be able to hold a dead accurate 12psi, because, as you say, the wastegate flows enough to hold as low as 10psi at redline. Any normal boost controller can increase boost above what the wastegate actuator is set to, you just can't run less boost than that.

I'd still be getting the original problem fixed though, the last thing you need is for whatever the problem is to suddenly get worse while you're out in the car.

[Jay95R33]

That's what I'm worried about too.

If it's a mechanical problem, (ie. wastegate flap not opening far enough) then I would be fixing it rather than buying a EBC to get it to work.

Seems like a strange problem, and it could be a combination of things that is causing it.

J

[otto]

well pulled the turbo out this arvo gonna try porting the w/g passage a little to c if that helps it doesnt seem fouled or anything hopefully ill have it all back in and runnin by tomorrow, let u guys know how i go.

[Cake]

my car is doing this now... full exhaust (split dump) with screamer...just had intercooler fitted, dump pipe and bov fitted couple days ago.. these are the only engine mods, still running stock boost setup. ok we all know stock boost has 2 stages, mine is sitting at 0.5bar before 5000rpm, then just jumps up and keeps increasing, has hit 1bar over 5000rpm, but i backed off, im guessing it will just keep rising. im guessing possibilities are hole in vacuum hoses, or wastegate flap isn't opening enough maybe its hitting dump flange, but i can sure hear it opens. how far does the wastegate flap open on a stock turbo? going to change some of the vacuum hose tomorrow since it could be dodgy.

[otto]

Yahoooo, success at last!

i ground the wastegate port out a fair bit (so there was less than an 1mm perimiter for the w/g and went for a drive this arvo and bam boots sat pretty dead on 10psi right through the revs, got full boost abit before 3000 (high side of 9psi pretty close to 10) crept to the low side of 10psi by 5000 then sat dead on 10 psi for the rest till redline. more than good enough for me. this was with the rb20 actuator havent tried it with a bleeder or the diy controller yet but im guessin it ill be sweet

so im off to get the safc tuned finally, thanks to everyone that had an imput.

[RBVS]

thats good to hear. the stock set up is good for stock but when you change things, mod, then you have to balance out the other stock aspects of the set up.

good effort mate happy to help

[Cake]

otto good stuff

changed my hoses today, that pretty much rules out the hose leak possibility.

went for a drive tonight, in 3rd and 4th once the stock second stage boost kicks in (over 5000rpm), boost still jumps from 0.5bar to 1bar, hmm this is not gonna be fun fixing this. i only want to run about 0.75bar or 10-11psi. not running any form of aftermarket boost control.

in 2nd gear reached 0.75 bar tops, only in 3rd and 4th it rises to 1bar.