Help 4 year boost problem
 

guys I need your help. My baby is only boosting at 9-10 psi and when I do boost I get a high pitch whistle which gets louder the higher the boost. Also the car doesn't feel as powerful as it once did as it no longer launches you into your seat.

It all started after I had an engine fitted in cyprus which came from API. So since then I have changed all vacuum hoses, induction hoses, turbo intake pipe (as it was split), waste gate/actuator, exhaust system (headers all the way back but these have a liquid gasket) and a new recirc valve. All the boost pills are present.

My car is a 1997 impreza WRX STI, grey import. No tuning has been done yet just constant repairs as listed above. the turbo is a vf24 if that makes a difference.

Can anyone suggest any ideas as the only two things left I can think of are the exhaust gaskets and the turbo :cry: :facepalm2:

Thanks n advance guys.

Is the Y pipe under the TMIC in good condition,
Your whistle is the leak, cant you find a rolling road so it can be run under load with the bonnet up to locate the source of the whistle ?

I have bubble tests and tried smoke testing on the tmic and all test showed negative. But I can't reach the pressures experienced under load.

There is a local place I've recently found that does have a rolling road but I'm looking for ideas for the situation I might be walking into.

Also I Have put new gaskets on the inlet manifold.

tried cleaning your boost solenoid?

High pitched whine/whistle is boost leak somewhere

Up-pipe blowing

Iv cleaned the boost solenoid as I have a cel light, for the tps and boost solenoid. After cleaning the boost solenoid cel cleared.

How can I test the up pipe? Or any pipe on the exhaust?

Have a look at it for signs of escaping gases. Double check the gasket on the bottom of the up-pipe

Had the same on my Bugeye, turned out to be the lower up-pipe gasket. Had to get under the car with the engine running to find it though.

Here is a link to what it sounds like that I recorded today. Its a bit blury but at best it hits 9 psi and won't go any higher

thats a split turbo hose after the compressor I would say a leaky Y pipe

Run hand around exhaust joints with car running to feel for leaks. Are the new header standard and unequal lengths? Is boost solenoid piped the right way round,only one restrictor pill on two port,goes in hose between turbo and t-piece,the t-piece that devided turbo pipe into solenoid and actuator. But to me you dont seem far off standard boost pressure already, imprezas boost to less than 1bar/14psi so 10psi is probably right.if you had a split in vacume hose on previous engine then it would have made it boost more and go faster,hence engine needing replacing because fueling wasnt mapped for boost leaking. Now new engine feels slow with new hoses etc. And correct boost.as for the whistle, turbos do whistle,or if you've changed downpipe ti decat

I believe they're unequal headers that I bought from scoobyworld. But the squeal was after the engine replacement and before the exhaust change. I changed the engine to bottom end failure. There is only one restrictor pill at the boost solenoid. I know turbos have some whistle but this is loud and everyone can here it when I boost. I thought it was meant to boost between 14 and 18 psi?

Do you know a way I can test the y pipe as I can re-create the pressure where it squeals ?

If you have a compressor you can rig up a DIY pressure drop system or a foot pump. I used a tyre valve a bunged off pipe work on a old car of mine and worked a treat.

This video tests the Y pipe and tmic

14-18psi sounds too much for standard,thats about 1.2-1.3bar,which is quite alot (im running 1.2bar with mods & remap at 320bhp) Should only be one restrictor pill on a 2 port solenoid and this goes in small hose that comes off the turbo before solenoid & actuator. If you've had air intake hose off at some point then check this is on properly at the bottom where connects to turbo. I dont think yours is the same as mine,mine goes under inlet manifold and staight onto turbo,where yours probably goes over it. But when I refitted mine once the bottom kept kinking in rather than over the turbo spigot,which would cause a leak if unnoticed. Also check intercooler pipework is tight and good connections

to bring this back alive and update:
so far i have changed the engine (now have an engine from API) then had to change the following as the leak began:

1-complete exhaust
2-all vacuum hoses inc turbo inlet and induction
3- replaced TMIC and new gaskets
4- Inlet manifold gaskets
5- Replaced Actuator
6- replaced recirc
7- All pills are present

i am now at a complete loss. what else can it be, im hoping not the turbo but seeing as iv had the leak that long surely the turbo would have blown by now??? if it were the turbo any recommendations on which to upgrade to (currently VF24)

It is definitely a boost leak, or the turbo whining.

It shouldnt be difficult to find, rather than replace parts willy nilly without been able to find the fault, take it to a rolling road.

You are replacing parts and wasting loads of money on stuff that isnt required you could have used that money to put it on a RR and diagnose the actual problem. I reckon an hour on the rolling road and your problem will become very apparent.

All the parts iv replaced so far have actually needed replacing minus the actuator.

Well it sounds to me like it is definitely a boost leak of some variety. Get it on a RR

boost leak without adoubt or cracked turbo housing

If it were a cracked turbo housing wouldnt if have completely failed by now seeing as iv drove it for over 4 yrs like it?

not really if its on the boost outlet side and not the main housing,but as you can hear in the vid its a load boost leak pressure test the system

Are you sure restrictor pill is in correct place? If its not in the pipe that comes off the turbo Before the t-piece that goes to waste-gate and boost solenoid,your actuator/waste-gate won't hold the pressure and will bleed off most your boost only providing actuator boost pressure. I repeat restrictor pill goes between turbo outlet and t-piece,Not in pipe between t-piece and solenoid nor t-piece and actuator/waste-gate. Or maybe boost hoses are wrong way round on solenoid.

Well had the car on a rolling road at the weekend, and the mechanic said that there is no boost leak and that he thinks it's the bearings in the turbo :/

He also did a dyno run with the following results

Attachment 16303

It's just a shame about the torque, but cheers guys for all your suggestions so far

Now thinking of upgrading turbo with a few other bits n bobs to make 400bhp, any ideas on which turbo to go for?

It could well be turbo bearing,I had one go once and apart from a bit more whine and a loss of power I had to assume it was turbo knackered and took a chance and changed it,which fixed the problem (I don't actually know what the fault with turbo was,only it wasn't working).
Did you ever try pill where I've said?

I had a similar thing, however mine on howled in high boost in 5th gear.

Turned out the turbo was loose and needed reseating, could be something to look at?

it wasn't discovered until i came to replace the injectors and TMIC that they noticed the turbo wasnt on right.

haha thats all well and good, but one thing i have learnt from experience is when a car isnt running right, dont boot the ass of it trying to fix it/troubleshoot ;) boot the ass off it when it is fixed :thumb: