matt75racing

Hi Guys
I have a 97 uk model that is boosting 9psi is this right , im running a 3" first cat back exhaust and a K&N panel filter the boost is strong and holds all the way to red line but I thought it was surposed to be more like 12psi , I have had the gauge checked and it is pretty accurate. of course I could be wrong about the psi as these uk models are a lower 208bhp than imports .

Regards Matt

Welloilbeefhooked

iTrader: (3)

9PSI is around wastegate pressure.

This is caused by either fitting a boost pipe directly between the turbo and wastegate or a sticking boost soleniod, assuming the ECU is controlling the boost.

Wayne.

matt75racing

Thanks for the advice and if im reading you right what im seeing is perfectlly heathly as the boost pipe for the gauge is coming of the inlet manifold at the moment, untill I can get a "t" piece! the xcar is totally standard apart from thee exhaust and filter

projectsubaru

9psi is too low for a uk97 with your mods, i would expect over 13 with just stock boost setting being used.

matt75racing

Ok thanks
Thats strangely good new as I have always felt the car didn`t pull quite aswell as as I hoped it would. any suggestion what would cause this ???? Matt

matt75racing

Just an update, have checked all the pipes and cleaned out the soleniod no difference, is maybe a adjustable valve is the way round it !! but dont like to Mask a problem... suggestions anyone ???
Matt

matt75racing

Anyone !!

tiny gsy

have you still got the standard plastic dumpvalve on it? Mine did and I found the spring was so solid that i could only just about open it by hand. Might be worthwhile checking

matt75racing

Thanks Ill give it a check , Hmm why would that affect the boost ? dump valve only open as you throttle off doesnt it

tiny gsy

From my understanding of a dumpvalve they open as it boosts and the noise is made as they close when you let off the throttle

matt75racing

Cool

Welloilbeefhooked

iTrader: (3)

Otherway round mate.

When boosting they are closed and when you close the throttle a vacuum from the manifold opens the dump valve and lets the air pass, which allows the turbo to keep spinning thus releaving pressure at the throttle body.

tiny gsy

fair enough mate, cheers

Still worthwhile checking it out though imo matt as mine made a huge difference when i changed from the plastic one

Welloilbeefhooked

iTrader: (3)

You are right though. If it is faulty and stuck open then it will never boost properly. Although it would be progressive with the boost loss.

matt75racing

thanks again Ill give it a check, but it doesnt feel like a bleeding / leaking type of fault I suspect the issue is elsewhere as the boost builds very strongly till 9psi then stops like its hit a wall and then holds there .
I take it the ecu tells the boost soleniod when to shut the boost off, but what tells the ecu what the boost pressure is ?

Welloilbeefhooked

iTrader: (3)

The MAP sensor tells the ECU what the boost is.

If your boost is constant then it doesn't point to a bleed of air, its more like a faulty or sticking boost sol (stuck open) or if the plumbing is correct its possible that your ecu is mapped for that boost level but unlikely if it has the OE ECU.

Are you sure its 9 psi and not 0.9bar?

Can you post a pic of the plumbing of the boost hoses?

Wayne.

matt75racing

Hi
not quite up to speed with attaching photos yet so ill try and explain the pipe lay out!!

From the soleniod we have two pipes one come directly from the bottom , this goes to the intake hose
the second hose comes out from the soleniod at a 90 deg angle this goes to the "t" piece on the wastegate , there is a third pipe that has what looks like a one way valve on it that goes from the inlet manifold to what looks like another soleniod . kinda hard to explain with out a phots to attach.

Welloilbeefhooked

iTrader: (3)

The t piece from the soleniod, does it also go to the turbo's boost nipple?

roscop

check the pipe that runs from the t piece between the turbo and the compressor. make sure that the brass restrictor is inside this.

matt75racing

Hi Guys
The t piece does go to the turbo boost nipple.
cant see any restirctor in the pipe !! which end is it in ? def not in the t piece end for sure.

roscop

look at the t piece between turbo and compressor.
the restrictor should be in the pipe coming from the compressor end to the t piece. think it is to the right of the t piece iirc. restrictor is about 5mm in diameter and is inside the pipe.

matt75racing

Hi All
I have ruled out the soleniod by removing it and fittting a bleed valve and made no diff no matter how much you adjust it even to point of completely closing the vacuum to the actuater off. 9 psi remains solid !! so i now figure it to be either the dump valve or wastgate acutuater or maybe a turbo problem , I have considered it maybe the wastegate is not sealing. any other ideas ??

matt75racing

Hi Guy`s and Thanks Guy`s for all the help I found the problem today !!! It was the dump valve!! so now to buy a new one , Question is recirc or atmosphere dump ? dont want it too nosiey so unless anyone knows of a quiet version I guess it will be a direct replacement
Thanks Again Matt

Skooby53

iTrader: (1)

Stick with the recirc if I was you. In my opinion less likely to cause a problem and there is no advantage to having a loud whoosh!

Welloilbeefhooked

iTrader: (3)

Totally agree!

tiny gsy

glad to hear you`ve found the problem mate