playing with my knob

[thesoundcriminal]

Hi guys my 850 t5 has lost its get up and go, I was giving it some stick on an on ramp and its sort of hesitated and it feels like the turbos not working any more. Its seems to still be boosting on the guage and is still making the whooshing noise, but its not very fast anymore. It has got a Variable boost valve on it could that have blown its self or something or maby a leaky pipe, i checked the pipework and there is nothing obvious, should i fiddle with the knob, I don't have any equipment to check the boost pressure, not sure what to do with it. No white smoke or anything runs fine no error fault.

[Filterlab]

Don't fiddle with your knob yet, certainly not until you have a gauge fitted.

Start with the uber-obvious stuff;

Check the air filter element for blockage and the air intake. If the air intake pipe drops off next to the radiator, you'll be pulling in hot air.

Make sure none of the BCS valve input pipes have come loose.

If you do have a variable boost control then check that it's not missing a piece (like a lock nut for example). Make sure the pipes are connected up.

Have a sniff round for any loose electrical connectors, if something comes loose it can make the ECU do all sorts of malarky.

Have you changed petrol grades at all? Going from super to normal can have an affect, although not a huge amount.

Has the pipe that feeds fresh air to the turbo come loose? There's a jubilee type clip on the connection, the screw points upright. If that's not tighter than tight then warm air will get drawn in and hamper performance.

Have you changed the HT leads lately? Poor impedance characteristics will not help.

[thesoundcriminal]

I actually went from normal to super could that be it the ecu confused or something Ill check the rest, its got a mushroom air filter I will fiddle with the feed.

[Filterlab]

Going from normal to super should boost performance. You could try this:

Disconnect the battery completely, then connect the leads together and switch the ignition to 'run', leave it five minutes, switch off the ignition, disconnect the leads and hook the battery up again.

That'll give your ECU a clean slate. Start up and idle for four minutes then take the car on a run with a varied driving style (i.e. some calm, some middle, some fast). See how that makes it feel.

[timbo_1975]

Burst hose or intercooler, or split recirc diaphragm i would say.

[thesoundcriminal]

I had a look at all the hoses and they all seem fine so I guess it could be something else. Arrr intercooler how do i check if its that.

[thesoundcriminal]

I have done the ecu reset and no change

is there a digram of all the hoses i should be looking for.

[thesoundcriminal]

pictures of relevant aria I think

[skirmish998]

just been playing with my recirc as have a DV to fit along with a blanking plate. I had thought the boost wasn't delivering as much kick as it had but gauge was still showing same boost. thought i had got used to the kick. after i had removed the recirc I had a good look over it and it was brittle and had a little hole about 4mm across. well worth having a look. it is damn fiddly without a ratchet mind. mine broke a few weeks back!

[cameron]

LOL a 10mm ratchet spanner is a must

[thesoundcriminal]

thanks guys where is the recirc thingie and how do i check to see if its the intercooler.

[madhouse]

thanks guys where is the recirc thingie and how do i check to see if its the intercooler.

2nd'd and also how easy is it to change the diaphram? And cost too??

Cheers

[skirmish998]

recirc on the 850t5 is down between the engine block and the turbo. held behind a triangular pod on the turbo itself. I'll see if i can find a link on here....
http://www.vpcuk.org/forums/showthre...0+recirc+valve

[skirmish998]

replacement recirc diaphram bits. uprated and from the states mind.
http://www.ipdusa.com/Volvo-850/Perf...p-72-143-5223/

[thesoundcriminal]

now that seems like a very likely candidate. I will get a new one of those asap. Where can i buy it from as that link was in the US i think.

[thesoundcriminal]

well i have checked everything and it all seems fine so I am going to bypass the variable boost control is it safe to do that

[cherry1809]

If you bypass it (Just join the pipes back together) It'll set your boost to standard, So will give you less to worry about when looking for the problem. I don't think it'll be the MBC, Sounds more like you've sprung a leak somewhere.
When I first bought it, It was hardly boosting at all, And the ECU light was on. A quick search and I found the boost hose that goes to the throttle body had been badly bodged and was split wide open. I replaced that, So unless it's popped off...
If you have a leak somewhere, It won't be long before the light comes on again. Have you run a diagnostic with the thing under the bonnet?

[bubba_1986]

Should mabye get a smoke test done to check for air leaks.

I had small one at bottom of intercooler, and air leaking from inlet manifold, volvo never changed gasket when refitting the etm

With leaks away still not right, though turned out to be the boost control solinoid a think, was 40 quid and boost fine now

smoke test shouldn't cost much either

[p fandango]

Should mabye get a smoke test done to check for air leaks.

I had small one at bottom of intercooler, and air leaking from inlet manifold, volvo never changed gasket when refitting the etm

With leaks away still not right, though turned out to be the boost control solinoid a think, was 40 quid and boost fine now

smoke test shouldn't cost much either

there is a small oil drain hole in the bottom of the intercooler anyway, have heard of people blocking them up tho

[thesoundcriminal]

I am basically crap when it comes to cars so i best take it to a garage, but I have removed the MBC and it snow smother not stuttering but not much more power. Ill try a smoke test I could do that that sounds like my kind of mechanics.

I not had any warning lights come up at all.


Also if i blow through the MBC it comes out the small blow off hole in the top is that normal. Thanks guys again for being so patient with me.