car wont boost over 0.5 bar

Came out of work yesterday and car felt flat. It's a bugeye wrx. Boost gauge was only showing 0.5 bar. When I got off the a19 I pulled over and popped the bonnet incase a pipe had come off or something but everything looked ok. When I drove off car was boosting to 0.7 bar then suddenly up to 0.9 bar which is about right as its more or less standard car. The rest of the way home was boosting to 0.9 bar no problem so thought it might have been a one off problem. But then today on way to work and way home did the same thing. Only up to 0.5 bar then after about 20 mins back to full again. Any one got any ideas???

The boffins will probs the answe for this 1.

Would u mind posting in the NEW MEMBERS SECTION and tell us all a bit about yourself were a freindly bunch and love pics..

baldy wrote:

Would u mind posting in the NEW MEMBERS SECTION and tell us all a bit about yourself were a freindly bunch and love pics..

+1

We are a very friendly bunch on this forum and we love our new members to say hello first and show us their car if they have any pics - I am sure you will get all the help and advice you need once you have said hello to everyone first

Mine does that,it's like it has no turbo until it gets upto temp

as said above ...

you shouldnt really be putting it onto boost until oil is upto running temp, which takes around twice aslong as the water temp

But saying that Finn, it should maintain its boost at all times, regardless of whether its a good idea or not booting it from cold, shouldnt it ?

Before I knew any better, my car was up in the rev range within 500yds of leaving Deckers car park and stayed there most of the way to Bishop. It never faltered.

Doesnt it still point to him having an issue ?

Just curious.

Normally I wouldn't be driving hard until it's had a chance to warm up but I happened to be straight onto the a19 and needed to accelerate hard on the slip road. As people have said above its not a good idea boosting when cold but the car should still be able to do it. This morning to test I started it up put my foot down out of the street and it hit full boost straight away. So I definitely think there is some sort of issue with it. Thanks for all the quick replies

Sound like you may have an issue with your knock sensor, have you done a fault code read?

No engine management light and nothing showing on my (cheap eBay) code reader.

If you drive the car, stop, start the engine again does the fault return?

I am thinking it could be the knock sensor picking up a noise from the starter or maybe a heat shield rattle.then putting the car into limp mode.

You say you have replaced other sensors too???

Are all of your earth points ok, also check the connection (bolts are tight) on the fuse for the live in the under bonnet fuse box.

Mine kind if does this but it does boost if you keep your foot down, so not sure if mines actually got a problem of if its just the car warming. Leaving it alone for now as I don't boost until the car is up to temp anyway(unless really needed).

Sorry should have given a bit more history on the car. A few months ago engine management light came on. Error was cam position sensor failed so had that changed. Shortly after got a new error code which was rear o2 sensor failed. The car had been running a full decat exhaust and had NOT been mapped for it. When the sensor was removed it was totally black with carbon and looked like engine had been really over fueling. Had the CATS re fitted and new front and rear o2 sensors (front probably didn't need changing but was the original sensor and was full of black carbon too). Car seemed much better and was getting much better mpg. That was a few weeks ago but now have boost issues.

Was just thinking , if the o2 sensors were full of carbon might the spark plugs be knackered too ? Might it be worth getting them changed anyway?