Loss in boost
 

Ok as the weather was nice today decided to take the 850 for a drive found a nice A road with a few roundabouts and too start with acceleration off the roundabouts was great, boost gauge going to the end of the white section as it has done since the Rica remap.
However after a few roundabouts accelerated off round another roundabout and the car didn't seem to have the same urgency it did previously. Looked down at the boost gauge and it was only boosting about 1/4 of the way into the white section of the standard boost gauge. Let off and tried again but this time having a listen for any abnormal noises ect. All sounded fine no warning lights on just hardly any boost.
Pulled over a little way up had a quick inspection to make sure all relevant hoses where still attached all o.k. Switch the ignition off and waited 5 minutes just incase it was an ecu glitch - restarted went off up the road again hardly any boost.
There appears to be no whistling or wind rushing noises the vacumn of the engine when stationary and decelerating is as it was with no change in the way the engine runs and it's still smooth when accelerating not coughing, spluttering or smoking just a very noticeable lack of power almost as if the car has reverted to standard tune. I have had a little search through the forum for boosting issues and people talk of a faulty bcs??? What I was wondering is being as the lambda light isn't on and based on the above description does it sound like a typical bcs fault?

Any advice or experience with a similar fault on this would be greatly appreciated :thumbs_up:


Cheers,

Andy

sounds like a typical boost leak to me although i could obviously be wrong. if any of the big pipes had come off then the car would start to stall.

the first thing i'd do is give all the pipes a good check over visually, seeing if you can pull any of them off with your hand(happened to me before on an old car). if nothing comes to light take the intercooler hose that goes to your throttle body. it's quite common to split underneath.

after that you need to start checking all your vacuum lines. common one to go is when you look on the left hand side, just under the inlet manifold. this is all part of stage 0 and if not done already really does need doing.

HTH

It could be one of four things.

BCS gone south leaking boost into the air-intake pipe
waste gate actuator has sprung a leak so not able to hold closed
An IC or pipework leak.
The chip has gone wrong

Have a good look round all of your IC pipes especially around joints (throttle body section)

Check all of your Vacume hoses especially the one on the intake manifold (Left hand side as you look at it) to see if any are split or detached.

As a temporary measure you could try to shorten the length of the Actuator arm to see if the boost improves but a pressure test is better (pump 5 psi into the actuator and see if it hold the gate closed)

You could hook up a MBC and set it up to boost to the end of the white area and then see if it holds.

You could build yourself a pressure tester and check the entire IC system for leaks. I'm doing this myself but still haven't got round to building the pipe work.

Because it happen so suddenly I would be inclined to think that a pipe has popped off or split. Or the intercooler has split (but that's unlikely but i'm starting to suspect this in mine)

The BCS do go wrong and you could try one from another car or bite the bullet and buy a new one.

Do you use the car regularly? If so, check the plugs to see if they are sooty then again in a few days which would indicate an air leak.

Mine went sooty within minutes not days :swoon:

It's unlikely but the chip could have gone wrong. You could ask for it to be tested. Luckily for me Don did this and also tried a new map all for free:thumbs_up:

Let us know how it goes:thumbs_up:

George

Dam,,,, beat me to it LOL

We were obviously typing at the same time

Hmm runs outside to check hose security.......:thumbs_up:

you're not gonna be this slow on track are you?:loser:


shouldn't have said that, now when you do see me it'll be like ayrton senna and prost running each other off the road lol

He might not be but I will with this level of boost pressure! :broken_heart:

Right all hoses appear to be secure, the one under the fuel rail all the connections of the vacuum tree, think thats what its called, the hose to the throttle body seems nice and secure and doesn't feel split. Hose to the top of the intercooler seems secure and the vacuum hoses to the actuator and bcs all appear in place and secure if not a touch crumbly. Going to see about getting a bit of vacuum hose and replace all the easily replaceable vacuum hoses I can get to see if that might be it but I am not convinced. If I was to disconnec the bcs and drive the car without it connected how would you expect the boost level to respond? Would I get no boost? Also would the lamdba light come on? Just thinking might be a way of testing the bcs??

George, car doesn't really get used much only at weekends, has been fine up until now although there has been two occassions when I accelerated in kickdown and there was about 4-5 seconds delay before I got full boost, got about the same level as I am now then like a switch full boost occured, although the last time that happened was a good 500 miles ago. Car is hot at the mo so won't remove the plugs just yet. Will probably wip them out at the weekend for a closer inspection. Think I might try and get hold of a bcs from Volvo and try that even if it isn't faulty no doubt running the higher boost levels that the remap requires will probably find a weak spot in it before long.

check the pipe that goes to the manifold inlet there is a small pipe that comes from the idle valve and joins the big inlet pipe found my small pipe was coming away from the bigger one yesterday

Just brought a new bcs myself from volvo they are 70 odd quid o can loan you one from my t5 if you like to test yours with