Inconsistent boost

[evo4Lee]

Hi all.
When my evo4 is over about 70mph in 4th or 5th it doesn't boost properly, I thought it felt like it was loosing power for a while, but when I have just been on the motorway I've been looking at the boost gauge and it flicks from anywhere between 0 - 0.6. From a dead start its fine in 1st 2nd 3rd 4th up till about 70 its boosting at 0.7 then it just goes crazy! Any ideas? the car is standard besides exhaust and manifold. Thanks!

 

[rich_f]

have a check of all your hoses and pipes

make sure they are all on and tighted up

 

[BRAVEHEART_STI]

sounds like what happens with a lot of turbo charged cars especially subarus

when u put the foot down the boost spikes in 5th gear ( goes slightly higher , it is a difficult problem to sort out but can be caused by having induction filters , decat downpipes , manual boost controllers etc but mainly the main cause ( if its spiking ) is a decat fitted