I recently picked up a Greddy Profec B for my STI 4 RA because I was having problems with creep even with a Dawes fitted. I installed a couple of weeks ago and have tried every setting going without much joy. I have been running on the lowest setting on the higher of the two settings and have been getting 16psi in 1st, 2nd & 3rd but in 4th over 6000rpm it just creeps up and up toward 20 psi. At this stage the knocklink says 'no you don't' and lights up.

Car has a Apexi induction kit and Mongoose 3" downpipe mated to a HKS 3" Hyper, I am presuming the downpipe is causing the creep ?

Anyway tonight I experimented by changing the Profeb B for an Apexi AVC-R (old type) that I have on my Fiat Coupe 20 VT. On the Coupe the Apexi worked spot on never creeping (also full decat, chip, hybrid etc). It seems to work better than the Profec, 1st, 2nd, 3rd no creep at all right up to 7500rpm but 4th and 5th it still creeps after 6000rpm.

I then fitted the Profec to the Coupe and it works spot on, no creep at all. Basically does every it says on the tin.

When I first got the car in May it was running the standard solenoid with a full Mongoose de-cat and I put the cat downpipe on to calm the knocklink down which worked but I certainly noticed the drop in performance.

Since then I have tried the Dawes, Profec and now the Apexi to stop the boost creep with a full de-cat and had no joy.

Anyone have a solution or have I just got to put the cat downpipe back on to stop the creep ?

I know I could re-map but that's £700 and can't afford that route at present.

It's really begining to pee me off now. Reel pain when you can't use the full rev range if you want to

 

Creep is a mechanical limitation - the best boost controller in the world will not fix it. Try connecting a piece of rubber hose between turbo outlet nipple and wastegate actuator, and give it a full power run through the rev range.

You should be seeing about .7 bar of boost (cracking pressure of the wastegate actuator). If it's creeping at high revs, your wastegate is unable to flow enough air to keep boost at .7 bar.

What turbo is on your car, and what downpipe? If stock, I'd be surprised if the wastegate is too small - could be related to a poorly designed downpipe?

Richard

 

Turbo is a standard VF23 and the downpipe is a Mongoose 3" Twin dump

 

Never seen a vf23 creep - I'd try an open necked d/p.

Richard

 

Could it really be that simple ? Would a HKS downpipe be better that has the wastegate exit closed like the standard item ?

Or is there something else I am missing here that is causing it ?

 

I never mapped a car with twin dump d/p, but the priciple is to keep the wastegate gases from interupting main turbo exit exhaust flow. However, penny only opens 45 degrees. So on a twin dump most gases are screaming straight into the side of the wastegate pipe. Logic tells me this isn't good, but I cannot confirm/deny. Someone else should come along with more info.

I would suggest confirming it is actually creep before doing anything else though - simple with a straight hose between turbo and actuator.

Richard

 

I would go for the Hayward & scott open neck downpipe.

 

Thanks Richard, I will give that a go tomorrow and post the result.

 

Okay, tried this morning and as suspected I get creep connecting a pipe between turbo and actuator Runs from 0.7 bar and by 6000 rpm it's up to 1.1 bar.

So question is, is this a downpipe problem or something else ?

 

I'd start by swapping the downpipe to an open necked one; I've never heard of a VF23 creeping.

Richard

 

Could it be a problem with the actual turbo ? Or maybe a leak from the exhaust somewhere in the system ? Would that cause creep ?

 

I would check to see whether the wastegate actuator/mechanism is operating correctly and moving freely when pressure is applied to actuator bonnet

cheers

 

Okay been checking things tonight, don't really know what to do with the actuator and can't see how to adjust but I got a big pair of mole grips and moved it backwards and forwards. There's plenty of tension there though.

I also made the pipes to my boost solenoid as short as possible.

Final thing was I checked exhaust for leaks and found one ! I have a smallish leak between downpipe and centre section where the two join. It was only able to notice with my hand held there whilst reving the engine. Could this be the problem ?

Clive.

Does anyone know where I can get a new 3" bore oval type gasket be the way ?

 

I've used "Instant Gasket" type products in the past between centre section and backbox, on 3" systems. You could try that as a short term fix if you cant find a gasket quickly.

 

I have seen a VF23 creep on a P1, ages ago. ( well, Im pretty sure it was a VF23, cant remember as it was a couple of years ago )

But it certainly sounds like the wastegate needs ported.

 

I suggest changing the downpipe, H&S do an open neck 3" tapering down to 2.5" off the shelf, but will do you a 3" straight through if you ask them.

I don't think a leaking exhaust at the centre section is anything to do with your creep.

 

Would the HKS type be an option as that blocks wastegate like the OE downpipe ?

 

I haven't had experience of the HKS, I don't know if your twin dump downpipe you have on at present has a tongue on it or not - if it has then this may be the reason for the creep (as has been said earlier in the thread). I had a twin dump pipe with a tongue in it, it started to creep above 17psi.

If the HKS doesn't have a tongue than I'd give it a go if you have one available, since it will work like the OE cat pipe but flow more freely. However if you had to purchase a downpipe then IMO I'd go for the H&S, since IMO it would flow more freely than the HKS.

The fact that you've got creep even at 0.7 bar with the twindump, and it goes away with the OE cat DP with full boost control, suggests the twindump is the reason for the creep, and the HKS would be better.

Edit to say H&S is Hayward and Scott, not HKS

 

Thanks for all the advise on this, if I get time this weekend I will fit the OE downpipe and see what happens with that fitted before investing in a new de-cat pipe.

 

Rather than buy the HKS, why not just remove the cat from the stock d/p?

Richard

 

Good idea, although I would have to get another stock one for MOT time

Anyway I have got a new gasket today so will try that tomorrow, then if no joy (don't expect it to be that simple) I will re-fit the cat and post results.

Clive

 

You'll pass an MOT on just the centre cat - much easier to swap than the d/p too.

Richard

 

Richard, you were spot on ! Just put the cat downpipe on and no creep whatsoever. Looks like I will have to keep my eyes out for an open neck pipe.

Would just like to say thank to everyone who's contributed to this thread(especially Richard).

Clive

PS can't use centre cat for the mot as I have a HKS system and the centre is a different length compared the the HKs centre

 

Consider having a 2nd centre section made up, with at least a 100 cell sports cat in. Any decent exhaust place can do it in an hour or two, and is probably the best solution assuming you then fit a decent open necked design down-pipe.

Richard

 

Certainly and option, although I'm getting a dab hand at swopping these downpipes now