loosing boost at high rpm?

[andybassett]

Hi all. this is my first post and am needing some advice.
i have a 95 850 t5 manual with the hlm 304 remap which im very pleased with. my query is that if i accelerate to high rpms eg 6000 in 2nd and 3rd then change to 4th the boost reaches about 13psi but if i accelerate hard from 1500 to 2000 rpm in 2nd 3rd or 4th the boost builds and settles at 16 to 18psi through the rev range. is this normal or do i have a problem? . i replaced the cbv valve and spring last week. any suggestions appreciated.

[Saaamon]

Was it fine by for you changed the CBV? May have a BCS problem, but i wouldn't like to say for sure.

[andybassett]

Was it fine by for you changed the CBV? May have a BCS problem, but i wouldn't like to say for sure.

it was just the same, i changed the cbv thinking it could be the problem. the diaphragm did have a split tho.

[Alan M]

I had funny boosting issues that hae now been cured with the replacement 2001 V70 T5 BCS fitted to my 850 T5. My boost value would be different every time I planted my foot. I now reach 17psi in the higher gears at WOT at high revs and that holds with no fluctuation and I reach 15 psi in 1st and 2nd at WOT at high revs.

[cameron]

Where does the gauge go to on the dial and does it drop dow the higher the revs you go ?

I have had the HLM 304 done also it would boost to the end of the white section but it turned out i had a boost leak :(

Since replacing the hoses and the PCV system it now boosts about 3 - 4 mm off the end and stays there :D

Maybe a hose check would uncover something :confused:

[timbo_1975]

Cam, did your transmission issue resolve itself?

[andybassett]

I had funny boosting issues that hae now been cured with the replacement 2001 V70 T5 BCS fitted to my 850 T5. My boost value would be different every time I planted my foot. I now reach 17psi in the higher gears at WOT at high revs and that holds with no fluctuation and I reach 15 psi in 1st and 2nd at WOT at high revs.

thanks for the suggestions everyone, my boost does seem very inconsistant. a few days ago i would only get 10 to 12 psi but today it acheived between 15 and 18 psi. as i said, wot from 1500rpm in 4th gear the boost builds up to 18 psi and stays there but if i abuse the gears by going through 1st to 4th and up to 6000rpm the boost stays at 12psi. do you have the part number for the bcs that you fitted so i can get one . thanks

[cameron]

Cam, did your transmission issue resolve itself?

Yes mate although there was no trans problem.

It was the NSF Wheel Bearing that was whining :doh:

[LeeT5]

First place i would look is BCS. After that ECU. If you have no MIL light on then it's fair to say you don't have a vac hose problem.

[BruceT]

V70 T5 2001, BCS: part number: 9473212

[andybassett]

V70 T5 2001, BCS: part number: 9473212

thanks for the part number. just to finnish this thread off i thought i would pass on my experiences trying to cure my boost issues. firstly when i purchased the car it was a standard 850 t5 with 155k on the clock, the engine management light was on but the rest of the the car was very good so for £500 i was happy. my lambda light was on due to fault code 121 maf sensor signal fault and fault 232 long term mixture fault. both of these faults were caused by a bad earth. cleaning the earth lead terminal to the engine and the one below the battery tray sorted this, so if you have maf fault codes check the earths first. obviously fixing these faults made the car run better but i wanted more. the hlm 304 was done -wow what a difference- thanks to hamish my t5 goes like i wanted it to!. recently tho i had this boost problem of basicly the boost being intermittant, this was fixed finaly by replacing the bcs or boost control solenoid. i fitted a newer type solenoid from an s60 t5 which works very well part number 30670449. just as a tip for everybody tho if you need a bcs solenoid ,buy one from a ford dealership, the exact same part is fitted to the volvo engined focus 2.5 st. i can get them for £30 +vat. volvo charge over £40.

[orse]

At the risk of sounding silly why not fit a replacement bcs for the car,an 850 one,why one from v70 t5 or s60?Are the 850 ones no longer available?

[andybassett]

At the risk of sounding silly why not fit a replacement bcs for the car,an 850 one,why one from v70 t5 or s60?Are the 850 ones no longer available?

the original type solenoids are much more expensive and are not as accurate at controling the boost.

[officerbrooks]

I had similar with my 2001 C70 and fitted the IPD BCS from Parts for Volvo's the result was staggering! Look at the IPD website and all will be explained.

[LeeT5]

...So i was right! BCS. Happy days. ;) Glad you got it sorted....of to IPD website now to read what they gotta say.

[Alan M]

Get your parts from Rufe and they will be a lot cheaper than at the dealers. A new boost control solenoid from a later T5 and the S60r item cost £39 ish from Rufe. The 850 boost control valve is around £65. You will have to mount the later model BCS differently to the original item as its shape is slightly different.

[matt_t5r]

Simon is that our R,s on Southend sea front, got probs with mine, fault code 5.3.5 turbo prob???????