Boost Problem

[allstaruk]

Hi guys,

My car has had a few minor boost problems before that have come and gone, anyway I went on holiday last week and left the car parked in the sun when I came back I had a new boost problem.

Firtsly just to confirm my boost on stock twins with the stock ecu should be 0.8 bar shouln\'t it?

Here is the problem, sometimes while I am driving I get normal boost and sometimes I appear to only get 0.2bar, I have done a bit of research and read the guide on autosportracetech.com and I think I have narrowed down the problem so I took the car out for a spin to see if I could confirm what I thought was happening.

While driving sedately off boost I can go to WOT and the boost picks up normally however if I drive on boost it gets to about 5k and dies away and if I drive on boost and change gear I get full boost instantly then when I change gear I get 0.2bar again.

Now what I thinking happening is that either a pipe or one of the one way valves to the pressure chamber hidden behind the powersteering pump has deided to stop working and its not holding a vacuum, under normall driving conditions off boost the car is recharging this vacuum which is why it picks up boost normally but under boost it is losing the vacuum which is why I can only sustain boost for a couple of seconds.

Does this sound likely? How easiy is to check the one way valves?

Also I am sure I have seen another turbo troubleshooting guide can anyone point me in the right direction to find it?

Thanks

Al

[jonrx7uk]

Easiest way to check 1 way valves is to blow through them.  You will / may have to take off the UIM (Upper Intake Manifold) to get to them, which may appear daunting, but after taking it off a couple of times becomes 2nd nature!

With the UIM off you will be able to see any broken solenoids / cracked hoses etc.

Cheers
Jon

[allstaruk]

I had a feeling that that was going to be the case, I think that I may invest in some vacuum line then before I do so I don\'t have to put it all back together to go and get some if I find a broken line.

Can you actually see a broken solenoid or do you need to test them.

Al

[carterjohn]

test them m8,and be very careful when you remove the old pipes.
the nipples are prone to snapping off the soleniods.
if your pipes are hard heat them up and they slide off,i would recomend getting some 3.5 mm silicone hose and replace the pipes going into the two soleniods at the front (remove the pressure tank in front of the manifold makes it easier)

pipes ringed on the left connect to the solenoids you need to look at,

[allstaruk]

Cool, what size vacuum line would anyone recomend 3.5mm or 4mm and also what zip ties is anyone using, surely ordianary ones won\'t stand the heat.

Al

[carterjohn]

i used 3.5mm m8 and normal zip ties.

[gmogle]

But make sure you put something over the intake and cover all the intercooler piping. You dont want to be dropping anything in them !!

[allstaruk]

But make sure you put something over the intake and cover all the intercooler piping. You dont want to be dropping anything in them !!

Damn good idea, I dropped a nut down the y pipe once.