JDM_Wrx

Hi, i'm having major trouble with boost creep. i'm trying to setup my hks evc boost controller but its not seeing stable boost. once this is setup i can then get my car mapped. i have tried removing the blitz sus induction kit, this made no difference. i have removed the downpipe and checked that the wastegate is opening fully, i have tried another actuator and again no difference.

i have removed all pipework from hks boost solenoid and run a short pipe direct from turbo (TD05 with 90 degree bend) to actuator and still creeps.

the car hits 10 psi at around 3800 rpm and holds fine until 5000rpm then it starts to climb to around 15 psi. sometimes, it has even hit the fuel cut.

the car is a 93 wrx with following mods.

scoobyecu 15.5psi base map
3" revolution exhaust ( turbo back)
megan headers (wrapped)
440cc injectors
blitz sus induction
pfr7b plugs
mrt inlet pipe
uprated pump and reg

knocklink + boost gauge

the only thing i can think of that is left to try is to change the downpipe to an open neck 3". mine has an outlet for the wastegate but isn't the biggest. i don't want to spend another £200 or so on it to find no cure.

how about porting the wastegate?

any ideas would be gratefully received, has anybody else experienced this?

thanks in advance
Rob

RoRu

What downpipe are you using?

JDM_Wrx

3" revolution downpipe

RoRu

Is it closed neck?

JDM_Wrx

no not exactly, has a wastegate outlet but is just big enough for wastegate flap to open into.

do u think the downpipe could be my problem? i don't have a problem with replacing it, i just want to make sure it will cure it.

cheers
rob

RoRu

I'm having the same problem i have a HKS closed neck d/p mapped to 1.49 bar but creeps to as much as 1.61 on the road, although i get no knocklink activity, on the last mapping session with Bob Rawle he said that it was an issue with the d/p and a open neck pipe would probably cure the problem.

JDM_Wrx

i think a open neck downpipe may cure mine as well, but i just know if i buy one then it will be the wastegate, it has got worse on mine since fitting the headers.

i might bit the bullet and buy an open neck one, can u recommend a place to get one?

when are u finding yours starts to creep, have u got uprated headers?

cheers
rob

RoRu

I have HKS headers

when are u finding yours starts to creep?(not sure what you mean)

JDM_Wrx

what part of the rev range does it start to rise. mine holds a consitant figure up to around 5000rpm then starts to take off?

RoRu

From about 5200 onwards just keeps on climbing, but by 6300 she flying

john banks

Just map it to run higher than the creep level all the way, or sort the creep. It isn't creep if it is at a lower level than what you want to run

JDM_Wrx

john, i'm not following. how can i map it, if i can't control it. if i run the boost level i want (ie 16psi) then as soon as we get to 5000rpm onwards, it starts to creep and bang we hit the fuel cut. if i could get stable boost, then i configure hks controller and map accordingly.

do u not feel it is a downpipe or wastegate issue???

cheers
rob

Jay m A

iTrader: (2)

Since you have a Revolution 3" centre section and backbox, I suggest the H&S 3" open neck downpipe. Thats the combination I have, its a good fit

imprezyou

Hi mate i had the same prob with mine cant remember what it was, something to do with the duty cycle, call this guy graham of sanspeed 0208 301 4676 he will sort it over the phone for you. HOPE IT HELPS YOU

JDM_Wrx

jay - did u have the same or similar problem with the revolution dp? where did u get your h&s open neck from?

imprezyou - thanks for the number, i'll give him a call.

john banks

I do feel it is a downpipe or wastegate issue, but it may creep to a lower level of boost than you can run with that setup - with the right fuel, ignition and boost cut settings. You need to tread carefully, but if you want to run 18 PSI to the red line say, then it might be quite easy to control. Need to check the fuelling on a wideband and have no detonation though.

You could also unhook the actuator arm so that you get no boost at all, then you remove all control and see the real creep.

Jay m A

iTrader: (2)

Never bought the Revolution DP, had one look at the pic on the website and decided against it - better ones out there. I hear they have now revised the design so that it is a true open neck now.

H&S are Haywood and Scott, or ScoobyExhausts as they advertise on this site. Have a look at the groupbuy section, you may have missed out there but all details on that thread.

JDM_Wrx

cheers jay

JDM_Wrx

can u remember anything else about this, i've tried contacting graham, but he is unavailable.

cheers
rob

Delboy2

I do also believe the downpipe to be the issue - the problem manifested itself whilst trying to set up the HKS Boost controller as Rob has already said, the boost controller reported unstable boost during setup and on investigation proved to be true. So the following was carried out :-

1 - The Wastegate Actuator was replaced with a spare that I had which didn't resolve the problem.
2 - The Wastegate operation was then checked using a regulator and air supply and was found to work correctly (Actuator 'cracked' at ~7psig) and operated smoothly
3 - The Actuator was then connected directly to the turbo nipple bypassing any method of boost control thus eliminating this

With the Actuator 'piped' directly to the turbo nipple the boost reached 10 psig and held steady until 5k rpm then rose steadily to 15 - 17psig @ 6.5k rpm.
The neck on the downpipe on the wastegate penny side seems relatively small and narrow which I believe is causing back pressure on the wastegate once the penny is fully open

It isn't duty cycle related as the boost is unstable with the EBC pneumatically disconnected as above.

Cheers

JDM_Wrx

i think i will order a open neck h&s downpipe on monday and try this. thanks for all your views, does anyone have anything else to add?

u never know if this doesn't work, someone might get a bargain in the for sale section!!


cheers
rob

Jay m A

iTrader: (2)

Yes, the open neck downpipe is available from H&S as 2 types, the most common tapers down to 2.5" to meet the OE centre section. The other is 3" straight through which is the one you need

JDM_Wrx

jay - do u know if these are off the shelf or do u have to wait for them to be made? will order one on monday but could do with it asap.

cheers rob

RoRu

Last time i spoke to H&S they said thay had 3"d/p on the shelf, but there has just been a group buy on them so that might of changed.

Jay m A

iTrader: (2)

When I ordered mine they said they would have to make it, received it within 4 days

JDM_Wrx

that's good enough for me, will let u know if it cures the problem...

JDM_Wrx

i'm back... with the same problem... just brought a H&S 3" open neck downpipe, fitted it and exactly the same problem. comes on boost, holds 10 psi until it gets to 5200rpm then climbs quicker than the rev counter till it hits the fuel cut at 17 psi.

WHAT'S NEXT???

Please Help i'm running out of cash and patience fast...

thanks
Rob

RoRu

Sorry to hear that Rob, not sure if i'll bother changing my Hks d/p now.

JDM_Wrx

RoRu - i would wait till i find the problem, i'm sure that it must be the headers, everything is fine until about time the headers start becoming most effeicent (5200rpm) then all hell breaks lose. i think the only thing left to try is porting the wastegate!!#

what do u think?

John Banks where are u, i need some help!!!!

Andy.F

You need to port the wastegate out I'm afraid. Not a big job once the turbo is off.
Open it out until you have a 1mm seat for the wastegate 'penny' to seal on.

In a way, boost creep is a good sign. It means your engine is flowing a lot of gas and breathing well.

The only other option is to fit something to lower the efficiency, such as a more restrictive filter or exhaust system but you don't really want to do that !

Andy