Boost Fluctuates

[cefiro]

Currently having some boost issues, what seems to be happening is on light boost the gauge seems to be waving so if I am driving along and take my foot off the pedal and try and level out the boost to say sit at 3700 the gauge will not sit at say 0.5 bar it will surge from say 0.3-0.5 like the boost gauge is waving at me. You can hear the BOV hiss and close and hiss and close. The turbos recently got replaced with steel wheel items , and boost seems to build alot slower than what it used to considering they are pretty much stock but steel wheel. when I changed the turbos also changed the wastegates as they came with the turbos. running stock boost controller as well. Full boost by maybe 4k????

Now I believe my problem to be related to either

BOV leak

wategate problem

boost actuator

or slipt in one of the lines going to BOV, wategate or boost controler

What I was think about doing is pulling the hose off the boost controller and seeing if it will hold boost better and faster spool up (obviously not floor the car = unlimited boost)

Anyone help me??????

[lachlanw]

what boost controller?

[geraus]

not a good idea to take off your hose, doing that will cause your turbo to overboost and could blow it up, Check if theres any hoses leaking , if there plugged in right etc.

[cefiro]

its the std actuator.

[cefiro]

Well disconected the acutator, and its still doing it its either a leaky BOV or the wategate opening?? anyone know any tests to check. I have a little compressor which I can run into the wastegates. How can I check to the BOV's????? it doesnt seem to be doing it whilst on full boost and will hold 14psi all the way(however it still could be leaking just cant tell) however its when building or maintaining boost it seems to fluctuate???

[cefiro]

Hey guys I am still having this issue tonight I removed the air filter to see if intake pipe was sucking shut (its not) You can really hear the BOV leaking back into the engine I had a look at the hoses and they seem fine. When building boost it sounds like machine gun fire with the BOV venting back to the engine which makes me think it related to the BOV. If I have it in a tall gear and floor the car and boost will rise and fall and you can hear it getting vented, Now I would have thought if it were leaking from a hose to outside the engine then it will run rough and miss and splutter. So is it possible one of my BOV is stuffed and leaking????? The car will run full boost fine however.

Cheers

[cefiro]

Also can feel power cutting away from the car when its happening, like a hiccup.

[exXU1]

Also can feel power cutting away from the car when its happening, like a hiccup.

[/quote

what side of the throttle butterflies is the line going to the BOV.

[cefiro]

the BOVs are being fed from under the plenum there is a box type thing attached to the block, its fed the factory location I take it never had an issue with it before. It would have to be engine side of the butterflies. Spent this afternoon pulling the front bar off and BOV's changed the lines to going to the BOV's. cleaned the BOV's. pulled AFMs off and intake box checked all connections cant find anything.

the car has been blowing white smoke latley (oil) and can smell it, dont know if its related or if I overfilled the oil when I topped it up a few weeks ago, I am stumped????????? and getting frustrated.

What about a head gasket????? What else should I be looking for, I havent changed the BOV line going into the engine yet as its a bitch to get to however it seems ok.

[cefiro]

Anyone??? Please

[RipNGrip]

Well cefiro, I have/had both of those problems. I currently have the fluttering boost... if i am at like 4 to 7 psi accelerator at 15% and the booster gauge bounces and there is noticable flutter when i boost and release. I current think that my actuator has died and i have been overboosting on occasions and it has lead to the stock BOV dying.. this leads to flutter but like u i have no idea how to test my theory

[cefiro]

pulled both BOV off and both seemingly worked ok. could blow compressed air through to the BOV and see if they hold boost I think thats my next step to blow air through and see if there is a leak anywhere. Should have done this earlier. I only installed turbos in my car recently so I am not sure if its related. I should have a new boost controller on the way soo however I dont think its the issue as i have pulled the hose to the actuator off to see how it holds boost and it was still doing it.

Also just blocked the PCV valve and no love.....

Edited May 13, 2009 by cefiro

[Sheriff Wan]

Sounds more like a leak to me.

Could be from one of the manifold gaskets... you said you just replaced the turbos - did you replace the manifold gaskets?

I would be looking for a split hose somewhere or your actuator has given it up, as you stated you can hold full boost it would be unlikely that you BOV's ar buggered...

White smoke is not oil - its water vapour - blue smoke is oil... you can check if you've overfilled it by simply looking at the dipstick marking... If it's too full just let some out via the sump plug and recheck the level.

My 2 cents.

[cefiro]

tried blowing compessed air through the intake piping today took off AFM and blocked one and put pvc end with bike valve in it. Did find a small leak where the boost gauge is linked into, havent started the car yet however I dont think its going to be my magic bullet. Now if I run air through there should it pressurise the sump as I pulled the dipstick out air gushed out????

Any other options????? Ideas??????