boost controller problems

[Mase]

When i installed a bleed valve a little while ago my car would try and run unlimited boost till it hit fuel cut no matter which end i turned it to. I went to the mechanics and we tried another turbosmart one and it did the same.

Does anybody know what is causing this? The thing was definately set up properly. I double checked on the turbosmart web page, i confirmed with the mechanic also.

Reason why i ask is that i know of someone selling an avcr quite cheap and he said that when he ran it on his ca18 it did the same thing. I would like to get an electronic boost controller but if it's going to do this then there isn't much point.

Does anybody have any ideas?

Thanks

Jayson

[rodhog]

Well it sounds normal

Most turbo's i have messed with /80% internal wastegate use a little "olive" inside the pipe all turbo's form IHI to Garret I know of use this even SR20DET stockers have it. I have not foudn one in a RB turbo yet but it should have it. As long as your "olive" is in fornt of your Boost controller it should allow you too adjust it.

with out it makes no effect.

[lukits01]

Yea Im also having similar problems

I just installed a Profec B and whenever I set it on high boost

I hit a fuel cut right about 3500-4000 Rpm

what's causing this?

[nissky]

- one thing to check

with bleed valve turned down to min, it should pass through all pressure from inlet to outlet, you can test it by blowing through it with your mouth

if you leave it like this and connect up you should have stock boost pressure,

as bleed valve is in pass through.....

also, assuming its a stock rb20 turbo, its only a short hose from compressor

to actuator, with nothing else to really cause a problem...

[druzilla32]

my dual stage controller didnt let me run under 14.7psi..

So i got rid of that and now have an old school turbosmart controller.. It seems to work fine.

I read somewhere that if the hose from the pressure source to the wastegate actuator is longer, boost will come on harder.. But has more chance of spiking, is this true?

[RbHed]

sorry to hijack d thread but wat do u guys mean by hittin fuel cut ?

[lukits01]

well it feels like there's a hole at certain RPMs when the car just jerks (same feeling like bouncing of the limiter)

seems to me like the engine isnt getting fuel or the throttle body shutting off

but thats impossible cause I was flooring it the whole time

Is this what you call boost spike or unstable boost?

[Mase]

well i checked my original hose from the wastegate to the turbo and there was nothing inside of it.

Anybody have any ideas.

thanks

[lukits01]

most people on the thread seems to think its to do with the spark plug gap

regap them to .8mm should solve the problem

[Mase]

well my question has nothing to do with yours sorry. If you read my post it asks about a bleed valve not being able to control the boost no matter which adjustment it is set at. It just tries to go all the way to 1bar and further but it hits fuel cut first.

Does anybody have any other suggestions please?

Cheers

[lukits01]

oh whoops my bad

sorry for hijacking the thread heheh

;-)

[TTT]

Mase.

When you install the valve, get yourself some NEW rubber hoses and try it like that rather than cutting the standard hose and puting it in there..

basically, don't use the standard wastegate hose at all.

get new hoses.

I did this and it worked fine for mine.

[Mase]

i did bud, i ran all new vacuum hoses everywhere!!

I'll try a different bleed valve or use the rb25 wastegate and see if that makes any difference.

Cheers

[nissky]

if your using an rb25 turbo on an rb20 engine, where are you getting

the wastegate boost signal from?

also the rb20 wastegate opens at 2 to 3 psi later then the rb25 one

but i still cant see how this would be a problem, unless the current one

is faulty and even a slight restriction in the line (open bleed valve) is

enough to keep it shut...

[Steve]

I would suggest you go back to the start. Remove the bleed valve and replumb everything to stock. Take your car for a thrash and see how it goes.

If all is ok, reinstall the bleed before the Wastegate. With the bleed valve fully shut (not bleeding) all the boost pressure should pass through and you will get stock boost again.

I can only suggest that if you shut off the bleed fully, and you are still getting unlimited boost, that the fault is not the bleed valve.

Bleedvalves are so basic in their design and operation, that, apart from spiking, they are virtually fail and fool proof.

[druzilla32]

i had my bleed valve completly shut and it would spike to 1 bar. sometimes in 3rd it would only JUST push .6bar.

I opened it up just a bit and it sits on about .7bar through all the gears.

[Mase]

this was all done originally on the rb20 turbo. The episodes of it going to unlimited boost i think gave the rb20 turbo the last kick it needed to pack it in. now i have an rb25 turbo but i put the rb20 wastegate on there to run a bit more boost. I thought that maybe the rb20 wastegate may have been slightly faulty and that was the problem so i was goign to try it with the rb25 wastegate back on the rb25 turbo. will do a bit of experimenting shortly. Thanks for the tips fellas