Car boosts to 14psi but then drops down to 10psi UPDATE!!! i hav blue spring in 007p

[Berg]

seems like i have a problem with my boost at the minute

if i put my foot down it will get to 14psi but then drops down to 10psi as revs go up

its revo stage one, cone filter, dv, exhaust, n249 etc etc

is this an N75 valve symptom?

or any otheer things?

i have checked most of the pipes and cant spot any leaks

 

[thewiizard]

its revo stage one, cone filter, dv, exhaust, n249 etc etc

I guess by 'dv' you mean diverter valve? What type of dv do you have?

 

[Berg]

Meant dump valve, unsure which it is though as it was on the car when i bought it

I saw your car the other day on newbold road

 

[thewiizard]

lol really? so you're Rugby then?

Urm, some valves can cause issues, for example, if the springs are worn they won't be able to hold the boost and will leak. You wanna get yourself either a Split-R or an 007p like;

http://www.forgemotorsport.com/content.asp?inc=product&cat=0108&product=FMCL007P

A really dodgy way of testing it would be to completely plug the pipe that goes into the valve and see if it holds boost then. If not it could be your waste gate or even turbo failing...

Spose I should mention that it could equally be the N75 valve as I recall this controlling the waste gate opening and closing.

Welcome to the world of the Turbo

 

[Robbie C]

Any faults with VAG COM? Check all vac lines and boost pipes for leaks too

 

[Berg]

lol really? so you're Rugby then?

Urm, some valves can cause issues, for example, if the springs are worn they won't be able to hold the boost and will leak. You wanna get yourself either a Split-R or an 007p like;

http://www.forgemotorsport.com/content.asp?inc=product&cat=0108&product=FMCL007P

A really dodgy way of testing it would be to completely plug the pipe that goes into the valve and see if it holds boost then. If not it could be your waste gate or even turbo failing...

Spose I should mention that it could equally be the N75 valve as I recall this controlling the waste gate opening and closing.

Welcome to the world of the Turbo

Yer from Rugby

hmm insteresting may have a go and see what happens

I will be changing the dump valve soon as most seem to recommend the forge gear

Strange thing is when i bought the car there was a spare N75 valve in the glove box lol

Ive already had more problems in 4 weeks than any of my other cars put together, i really was expecting it though

 

[Berg]

Any faults with VAG COM? Check all vac lines and boost pipes for leaks too

Ive been told VAG COM wont point the finger at any certain part?

I dont have VAG COM so havent had the option yet

have checked all piped and lines for leaks now and i cant spot any

 

[Robbie C]

VAG COM will tell you if there's a problem with the N75 and may help pinpoint any other contributory issues. It's the next logical step unless you want to start replacing parts at random.

 

[tommy2008cupra]

revo stage 1 should hit 20-21psi peak anyway i guess dv, boost leak but defo vag com first anyway otherwise it is just a guessing game

 

[Berg]

revo stage 1 should hit 20-21psi peak anyway i guess dv, boost leak but defo vag com first anyway otherwise it is just a guessing game

Really? ive only had it 4 weeks but i has never boosted that high before

Ill see if i can locate someone close to me with vagcom

How can i tell if i have the correct bov for my car? as i heard incorrect ones can cause trouble

My engine management light is also on i forgot to mention

 

[tommy2008cupra]

ye it should do breifly, wont hold it for long though, best option is probably forge 007p dv as i have split r valve not to impressed tbh, prob have eml for incorrect flow through d.v but do get it on vag com asap

 

[thewiizard]

I've got VAG-COM mate but does anyone know which blocks are most suited for checking for the N75. I can see that 110-119 are mostly related to turbo control which should provide some idea as to what's going on but not entirely sure.

http://www.ross-tech.com/vag-com/m_blocks/110-119.html

I know that the function testing in VAG-COM checks the N75 valve but not sure how reliable this is...

 

[dave_6]

the EML light is on he said so vagcom will find a code which might explain things before logging anything else

 

[jassofr]

i think u have a leak.... check all vacums

 

[Berg]

I've got VAG-COM mate but does anyone know which blocks are most suited for checking for the N75. I can see that 110-119 are mostly related to turbo control which should provide some idea as to what's going on but not entirely sure.

http://www.ross-tech.com/vag-com/m_blocks/110-119.html

I know that the function testing in VAG-COM checks the N75 valve but not sure how reliable this is...

the EML light is on he said so vagcom will find a code which might explain things before logging anything else

Seems like VAG COM will be an ideal first step then

Could a dump valve/bov cause this?
ive heard the wrong ones can throw light on and cause some issues too

Im unsure what mine is as it was installed when i bought the car

Cheers for the help here by the way

 

[Berg]

had it on VAG COM today and no codes relating to boost issues

the n75 valve was also changed and that made no difference and seems to be working how it should


i have just taken off my forge 007p and it has a blue spring inside

is this the correct spring for my car on stage 1?

 

[s1l3nc3r]

What were the codes that you got from vag-com...??

Just because you are not boosting as high doesnt mean its defo a problem with boost MAF, coilpacks, etc can cause boost problems if they die...

When i had my forge d/v it had a yellow spring although it wasnt mapped at that point the ratings on there spring colour are...

Green - 6-8 PSI
Yellow - 10-12 PSI
Blue - 14-16 PSI
Red - 18-20 PSI

 

[s1l3nc3r]

Just pulled this off the forge site aswell relating to spring ratings...

Please Note:
The quoted spring pressure (Psi) relates to the un-assisted clamping force of the spring and should NOT be taken as an equivalent to boost pressure when determining suitability. Once a valve is fitted to a car it is subjected to various pressures that act upon the diaphragm or piston to aid its respective ability to seal or hold boost. An example of this, would be when using a FMCL007P valve on a 1.8T engine as found in the TT 225hp. The boost pressure on a "chipped" car can peak at 26psi. The recommended spring would be the Green or Yellow

For information regarding which spring is suitable for your application please contact us

 

[Berg]

i will be contacting forge tomorrow about it

ive read some threads on here and people have said they use the green or yellow and it still boosts to 20 on stage one

i read that if the spring is too stiff (blue or red) this can cause problems too

as above forge say the spring rating relates to clamping pressure and not boost pressure which i first thought

 

[jassofr]

maybe you should try another bov, synapse or hks ssqv that doesn't deal with springs...