TonyFlow

I have a MY 99 STi 5 Type R, pat spec 3" D/P(with splitter), nur spec R back-box, PE Power induction kit, ECUTEK 3 remap. All has been fine (except knackered MAF - prob due to ITG panel filter - which is why i replaced it), went to see Pat to get the car checked over (make sure it wasnt running lean), and when data-logging, the car now boosts OVER 1.55BAR (not good - target is 1.3!) and hits boost cut.
Pat reckons the wastegate is now not venting enough gas to allow the car to control boost (only happens under load - clever use of the throttle will restrict it to 1.3 bar - so I can drive it relatively safely), and getting it ported by 1mm should solve the problem!

Is there anything else I should check before getting the wastegate ported,(as I had an expensive month, Tyres, brakes, MAF unit, Road tax)?

Cheers

scoobyslut

What about simply adjusting the air restrictor size that bleeds the air off the the boost controller valve? That would then drop the boost pressure easily and simply.
So, dependent on the restrictor diameter [internal] you have at present, you realistically need to try ,say +0.2mm over what it is now. Dont worry if you get it wrong, you can simply solder the hole up and re drill again, so its costs as much as that.

john banks

Where in the rev range is it overboosting?

How about connecting the turbo compressor outlet direct to the actuator?

The_Judge

Is the wastegate solenoid 2 or 3 port? If 2, a 3 would work better with the Tek3. Also, have you tried cleaning the solenoid? Other than that, as scoobyslut says, the restrictor size could make a difference. Or as JB says, disconnect solenoid hose from the T-piece and plug it, and replace the T-piece with a 2-way connector. This works in a similar way to a MBC, but would be purely based on the bore of the restrictor. Would probably be far easier to just get a Dawes or equivalent...

TonyFlow

overboosts above 6krpms (when engine is loaded), wastegate duty drops to 0 on the deltadash software when overboosting.
Only a 2 port solenoid, boost was fine before induction kit.
can i have some pictures of what to blank off, and what to connect with 2 way connectors?

Dont want to drop the boost from its 1.3bar target (I assume the fixes mentioned will need a remap to recover boost lost?

The_Judge

I think your best option (albeit the dearest) is to go for a 3 port solenoid. I think they're about £140. This would leave the ECU controlling the boost, which let's face it, having spent all the money on a Tek3, is probably the sensible option.

However, I've been using a GBE MkII manual boost controller for ages with no problems. A simple twist turns the boost up or down as required. I kept meaning to try out JB's idea, but never got round to it. Based on that idea, I intend to try fitting a small bolt to the bottom end of the T-piece (the bit the solenoid hose came off) and effectively use it as a valve, screwing it in to increase boost pressure, and out to decrease. Should work in theory, but alot of the things I try work in theory... Also, I think the wastegate actuator arm can be tightened a couple of turns.

So that's another option for you. But if you want to go down the MBC route, there's some good info here...

TonyFlow

being as it is only at high rpms, I assume (from another thread RE Dawes devices), that this could be "boost creep" (i believe that is what Pat is saying is the problem - i.e. wastegate not flowing enough), will the fixes mentioned work for this (I asked pat if a 3 port solenoid would help, and he didnt think it would, he is convinced that the wastegate is not flowing enough)

john banks

Yes it is boost creep. You do need to port the wastegate. Hence my question about what RPM.

The_Judge

Ahh, I see. So the wastegate is basically doing the absolute most that it can to vent off exhaust gases, but it isn't enough, so the boost continues to rise. Got'ya...

As an alternative, if you didn't go down the wastegate porting path, would a manual boost controller with a slightly larger bleed hole also help...?

stevejohnson511

what is the downside to putting the standard airbox back on?would this not stop overboost and not cost anything.

The_Judge

If this has all started since installing the upgraded induction kit, then yes, putting the standard air box back on with a STi/K&N/Green/JR panel filter may sort the problem...

john banks

Obstructing breathing to cure boost creep is a bit backward... think about it.

If the wastegate won't flow enough, it won't flow enough period.

Prove it by connecting the actuator directly to the compressor outlet.

stevejohnson511

the way I see it is,the extra air flowed is just going straight down the wastegate if it is ported out ,so how will this benifit the engine?

TonyFlow

Dunno, but if the extra air from the induction is causing boost creep, then surely it proves the induction kit is working (OK a little excessively at high rpms - but surely it must have benefits lower down the rev range?) Wanna keep the induction kit, as I believe it must have made a substantial difference to air flow (hence the "problem").
John, Pat says that the wastegate needs to be ported by about 0.5-1mm, does this seem about right to you? What difference will this make to the boost level (I understand that I will need to get it rmapped to account for the porting)?

Will connecting the actuator to the compressor outlet be OK for testing purposes (as I will need to reach the High RPM/Load area, and as such, boost will be at ~1.3bar)

zhastaph

Yes, it will be fine. Just ensure that you plug the hose that goes off to the boost solenoid else it will draw in unmetered air.

Though, IMO I do not think it will prove very much. Connecting the compressor outlet directly to the wastegate actuator will meant that the wastegate will open at the pressure that it is rated at (7/8 psi), and boost will be limited as such. At this boost, the engine isn't going to be moving as much air, and I do not believe that this is going to be enough to overcome the effectiveness of the wastegate. Meaning in this configuration you shouldn't see boost creep.


As a short term save to the remapping you could always go for a manual boost controller like the Dawes.

Bob Rawle

Check the boost control pipework, I've never seen a VF28 suffer from boost creep although there is always a first time, normally, a two port struggles to make decent held boost, you could have a partially blocked restrictor. Check basics first b4 starting to swap things over. If you can control it by rolling in the throttle then the wastegate is able to flow enough air, its just getting "pushed" on spool up. If its genuine creep a dawes won't help it and it will still creep even with the actuator and turbo outlet directly connected.

bob

carlos_hiraoka

Bob, remember he is using a "3inch D/P with splitter" .....

Carlos H.

TonyFlow

the 2 port was controlling boost fine b4 the induction Kit went on, what is the significance of the wastegate duty being at 0?

Carlos, what is wrong with a 3" D/P?? I thought it would be best to advise people what mods I actually have rather than just say D/P (as that would cover a varying range of designs), and being a mechanical numptie, i thought it may help with a diagnosis!

Bob, is it worth trying to clean the solenoid, and take of the pipes and spray with some brake cleaner?

Bob Rawle

Carlos, yes but even with a twin dump squeezing the wastegate flow to increase gas flow through the turbine this would be unusual.
Its easy to go off and change this, change that ... I am merely advocating checking the obvious first.

john banks

I saw an STi5 Type R that was boost creeping (genuine with direct actuator connection) with a VF24 fitted after earlier engine failure. The VF24 is similar to the VF28, there may be subtle differences in wastegate, but not that I am aware. This was a twin dump Magnex downpipe oddly enough. This car also had a failing fuel pump. A lambda voltage of zero on a working narrowband above 6000 RPM with 20 PSI boost was only done once whilst I was logging but the car had been driving around like this! The wastegate linkage had free movement.

The direct actuator connection tells all - it avoids question of everything else except the actuator mechanism and the flow through the wastegate. It replicates the effect of zero solenoid duty cycle but removes a load of other control variables that confuse the issue.

A direct connection with a genuine boost creeping car will usually show 8 PSI (as most of the actuator are set to about this) and then go up to say 20 PSI at the top. I've done it several times now, a flat 8 PSI to the top or trivial boost creep proves it is a control issue.

I knocked a few PSI off my 20G at the top by removing the splitter in the turbine housing - it was already ported though as well.

john banks

VF24 is a C418 rather than C395 actuator but still rated as 8 PSI. There is no other difference on the spec charts.

TonyFlow

I reckon that when I have said wastegate duty cycle was 0, it was actually the solenoid, (told you I was a numptie)!

Don't really want to change the splitter, as the car has been running spot on - just my changing things has buggered bits up!

I gues 1st thing to try is checking for blockages, if that doesnt solve the issue, connect the actuator to the outlet, and if it still creeps, then port the wastegate?

Again, does 0.5-1mm sound about right for porting the wastegate?

Thanks all for your help!

john banks

Depends how much meat you have to port out to still give a good wastegate flapper seal.

TonyFlow

therefore, is it best to port out as much as it will go, whilst still keeping a good seal on the flapper (i.e. flapper diameter = +1mm from wastegate "hole" diameter)? I assume that this will make the car run fairly cr4ppy until a remap can be done to sort the boost?

john banks

Yes. But you could always use an MBC.

TonyFlow

I would rather get the car remapped when the wastegate has been ported (dont really want any "external" factors controlling boost!). Will there be any benefit in changing to a 3port boost solenoid?

john banks

A Dawes will control boost better than anything else bar an AVC-R IMHO. Others prefer a three port solenoid.

TonyFlow

what would I need to do to set up the dawes then John (I assume just drill the restrictor in the Dawes until boost reaches 1.3 bar)?

john banks

You just adjust the Dawes a turn at a time until it reaches the right boost. I would suggest a 1.0mm bleed hole for your turbo.

Check with the mapper what the boost level should be at the top - it will probably drop a bit at the top anyway.

TonyFlow

OK, so I cleaned the Solenoid and relevant pipework with brake cleaner today, went out for a spin, and it now appears that boost is reaching 1.3 bar and holding, until high in the rev range where it will slowly creep up to 1.4 (doesnt seem to go as high as 1.55 anymore). Is it worth trying to clean the solenoid/hoses some more to see if it brings it back down to touch (although knock-link isnt that active when it swings to 1.4bar)