Turbo flutter after change in setup. Help?

Hey guys!

I was going through the forums but couldn't actually find what I was looking for or maybe didn't look hard enough (sorry if repost!). This will be kinda long post but your help is much appreciated.

I own a 97 A/T Glanza V. It was stock when I got it. I changed the exhaust manifold and downpipe to mildsteel ones from Speedvision CPS. The car ran fine. I got a *ahem* replica HKS BOV and it sounded sweet. Other turbo owners commented on how sweet and high pitched the sound was. I loved it! I bought a Turbosmart manual boost controller (too broke to afford an electronic one) without getting other supporting mods. But I do have an HKS adjustable actuator. I adjusted the screw on the top of the boost controller turn by turn just to up the boost by little. It ran fine and boosted fine.

Engine bay with BOV location. I saw an image of a starlet GT in an online magazine (scanned I think) with the same BOV location and decided to replicate it. Actual image of my car (note: this was before installing the boost controller):



I changed the stock TMIC to an RX-7 TMIC and relocated the BOV without changing anything else -AND- then came the problem!

Image pulled from the internet. Exact same location/setup:




It started to flutter. I hit the throttle and let it go it would flutter. If I held on to the throttle long enough and let it go, the BOV would sound off but the old noise was gone and it sounded like a dying mouse. The car felt different and didn't deliver the "oomph" it used to. I changed the turbo (as it was getting old) with a recently rebuilt CT9b. I thought it might (don't know why) fix the issue but it didn't.

If I adjust the boost controller, the car hesitates to pull. I put my foot down and the car wants to boost but feels like a strongman is holding it back. It revs up but doesn't go anywhere. I reset the boost controller to its lowest setting and the car boosts normally without hesitation but still the old feel is no longer there.

I want to know what I did wrong and how I can resolve this? ANY help will be a godsend.

Also, my Power and Manual button doesn't work - it doesn't affect the car's performance but thought I'd mention it.

THANK YOU SO MUCH FOR READING MY LONG POST!

Placing a dump valve closer to the turbo will have you hear more flutter.
Placing it closer to the TB will have you hear more 'whoosh'.
As for the change in behavior, I was too lazy to read the rest of the post and analyze it. Can do so later though..

Heya,

Ok having rebuilt around 30 subaru impreza engines and had 7 gt's, and been modifying turbos for best oart of 11 years
This is what i......and not in any way saying you SHOULD do as some people can jump down ya throat.

Firstly check all seals, gaskets, cable ties and jubilee clips and rule out that you are not losing pressure.

Wind the spring tension screw out from the bov and make sure you vacum pipes are all tight with no leaks.

I would just bypass the man boost controler just to run it without and see if it happens wigh that off.

If you dont want to bypass the mbc the check its installed the right way and open it up to allow the waistgate to open at factory psi.

Turbo flutter is backpressure bouncing between the compressor turbine and throtle body, not good for turbos but can sound cool. If u are getting flutter then some how the bov is not operating as it should and it could be spring tension to tight, vacum hose damaged or not fitted properly.

Its just a process of elimination really.
But if the basics are covered then u can start looking a bit deeper like bov diaphrams, waistgate, turbo compressor seal etc

Good lick and keep us posted

Thanks for your replies. I don't blame you dark_knight it is a fairly long post but if you could look into it and help out then that would be great!

terryproductions - thanks a lot mate. I did check all related pipes for pressure loss but they all appeared fine. Will check again. I opened up the BOV once but it didn't have any adjustable parts! The spring was fixed. Replica after all. I will try it with another BOV and see if that helps.

The next step I was planning was to bypass the MBC. Let's see if that helps.

I know the dangers of turbo flutter and do not find the sound "cool". I want to get rid of it! What puzzles me the most was I only changed the TMIC and everything went downhill from there

what have you done with the standard dump valve? i see on your first pic it is still in place with the vacuum hose so you were essentially running 2 dump valves with the configuration.

if you have done it the same as the other picture you are now running with just the fake hks. this will be your issue. if you want to get rid of the flutter sound you need an adjustable valve, a valve with a weaker spring (baileys or similar would be ideal) or you need to adjust or change the spring on your current one.

dac69er the standard dump valve has been removed now. Thanks for the insight mate. I'll be looking out for a better BOV then.

You have not mentioned where you have taken the vacuum lines (small pipes) for your BOV and MBC. Can you shed any light on that or post a quick photo as I think that could lead to an issue.

weeJohn this is my current setup. Excuse the mess, haven't been able to clean due to lack of time.

Current setup:



Close up of MBC:
The vacuum pipes (black ones) go from the turbo to the MBC as specified by Turbosmart manual. One additional (yellow color) one goes from the stock dump valve position to the stock solenoid to keep the ECU happy, as Turbosmart told so.


From BOV:
The hose from the BOV nipple goes to the inlet manifold


Note again, I didn't remove the MBC hoses while installing the RX-7 TMIC, only shifted the BOV and reattached the hose to the inlet mani

BOV looks ok, not sure about the MBC pipes and that yellow one is off the air inlet and I am not sure about that. Have you bypassed the stock hi/low solenoid?

The MBC looks like its plumbed in ok (from what I can see). As long as one of the pipes on the MBC goes into the oulet on the front of the turbo and he other goes on the wastegate/actuator its plumbed in ok.

The yellow one on the air intake should go to the hi/lo solenoid, unless like John said you have bypassed it. In which case that yellow pipe wouldnt be doing anything.

As for the turbo flutter - I always thought this was just normal flutter which is being amplified through the open airfilter? If you put the airbox back on the fluuter would go, so nothing to worry about

Cheers

Mark

Yes, one pipe goes from wastegate to MBC and from turbo to MBC as shown in the tut video by turbosmart. The stock solenoid is electronically connected and there is a pipe feeding it - turbosmart said it to keep it that to 'keep the ECU happy' and honestly I had absolutely no issue before the IC swap.

Thanks for your input guys! I've decided to replace all joined pipes with single running pipes and getting a new BOV to see if that resolves the issue. Will update as soon as they happen.