Intermittent low boost

[olliecast]

Hi guys/gals,

Apologies for my first post being this but i`m having a problem with my boost.

By the way, had the r for a week and enjoying it apart from this problem and getting to know the lady in shell far to well!!


Turbo plumbing etc all stock. 3" turbo back exhaust, and k&N filter are the only engine mods.

Took the car out after changing the oil and it was only boosting to ~.5 bar (on aftermarket boost gauge). Let the car cool a bit then it was back to 7.

Then, earlier on i put my foot down, the boost built then suddenly there was a step change in the car and on the gauge from the .7 boost back down to .5.
Only difference seems to be when the oil is slightly lower than 9 on the temp gauge

i`ve checked all of the boost pipes (aftermarket blue ones) and they look fine. checked ecu and there`s no faults.
idle is about 1000 to 1250 if that makes any difference.

any ideas what could`ve caused the variation cause its a bit annoying

cheers,
ollie :-D

 

[jameswrx2]

If you've got the std boost solenoid in play (?) then there should be a restrictor in the standard boost control pipework. If someone has changed everything for blue pipes then there may not be a restrictor in there.

To be honest, unless you get it completely stock you could be messing around for ages trying to sort stuff.

 

[olliecast]

If you've got the std boost solenoid in play (?) then there should be a restrictor in the standard boost control pipework. If someone has changed everything for blue pipes then there may not be a restrictor in there.

To be honest, unless you get it completely stock you could be messing around for ages trying to sort stuff.

do you know which pipe it should be in mate?
what effect would not having this restrictor in have?

 

[jameswrx2]

I'm not 100% but I think it's the one from the side of the inlet manifold, ie the boost feed.

It may not be directly related, but if you've got problems with boost it'd be wise IMO to get it to a known reliable setup, if you see what I mean.

 

[olliecast]

I'm not 100% but I think it's the one from the side of the inlet manifold, ie the boost feed.

It may not be directly related, but if you've got problems with boost it'd be wise IMO to get it to a known reliable setup, if you see what I mean.

yeah definately mate. Thats what i`m trying to do before i go to the 1 bar loop but this inconsistancy in boost has made me hold my horses a bit.
would a solution be to then put a restrictor back in the pipes then?

 

[another sunny]

For all those clever bods on here, what exactly happens if you remove the restrictor pipe and say put in 6mm or even 8mm id silicone pipe all the way through?

 

[jameswrx2]

For all those clever bods on here, what exactly happens if you remove the restrictor pipe and say put in 6mm or even 8mm id silicone pipe all the way through?

If you're running the std boost solenoid and do this then you'll see a lower than standard boost level.

You don't need it if you have an aftermarket boost controller obviously, but when using the stock solenoid controlled setup you need it in there.

 

[youngsyp]

Have you checked your actuator ?

 

[another sunny]

If you're running the std boost solenoid and do this then you'll see a lower than standard boost level.

You don't need it if you have an aftermarket boost controller obviously, but when using the stock solenoid controlled setup you need it in there.

I have just done the 1 bar boost mod(just joined the pipes together to by pass the solenoid) . what sized restrictor should i use/fit?

 

[olliecast]

well my boost is just below 7mmhg at the moment when its boosting properly. is that around standard. (goes to about 5mm hg when limping)

 

[olliecast]

rite, just fitted a different ecu and been for a 15 min blast. got the oil nice and hot. went up and down the bypass. held ~6.5mmhg all the way to 6,000rpm. fingers crossed its cured it x x x

 

[olliecast]

disaster!!! bloody limp mode has come back again. still no det sensor code on the ecu!!
only happened after about 40 mins driving though (longest i`ve done since i changed the ecu!)
can the det sensor be knackered and still not throw a code?
could it be heat soak?

 

[the chief]

mine used to do this when it was standard. driving around town (when the intercooler was warm) it woundnt make full boost. but on the motorway it would be back to normal. if your running standard boost the gauge shouldnt hit the 7