Turbo Boost Control Valve / Solenoid

mad hatter · Post by **mad hatter** » 01 May 2011, 20:14

My 2004 xc90 has a surge when accelerating. After searching for a while, it sounds like its probably the boost control valve. Can anyone point me to where this is at and/or how to replace it. I'm a fairly experienced self proclaimed shadetree mechanic but this is my first volvo and I can't find a repair manual. Also, if anyone knows where to get a good repair manual, that would be fantastic.

Post by **kcodyjr** » 01 May 2011, 20:24

It's secured to the airbox and has three vacuum lines. If it's misbehaving, your first move is to check those lines.

mad hatter · Post by **mad hatter** » 01 May 2011, 21:50

Thanks. Found it. Checked all three lines and they look good. Anyone have any comments before I buy the control valve. Like I said, its surging under load. If I acclerate slowly, I don't notice it. But if I try to accelerate quickly, it surges. It still goes but i get a constant repetetive surge as the RPMs increase. Kinda of rythmic.

Post by **kcodyjr** » 01 May 2011, 22:40

"Look" good? That's nice, but hardly definitive.

Start it up and squirt some carburetor cleaner at the hoses, especially the ends. If the engine doesn't pick up a few RPM's, then the lines are good.

Before you go swapping out a TCV, cap/rotor/wires/plugs/filters are recent?

kilmidyke · Post by **kilmidyke** » 02 May 2011, 09:13

Hi, 1st post newbie here.

I have been advised by a local volvo mech that this part needs replacing on my 2003 Xc90T6. The check engine light is on and shows a code of P0134 which is for the front o2 sensor. The o2 sensor has been "back checked" and is working fine apparently. He says that because the valve isnt working properly that it will flag this error code. Is this true? I would have thought that the boost pressure valve would have a code of it's own.

Any and all help or advice is appreciated.

Also, had the dreaded transmission failure at 115,000km. The good news was that Volvo Canada stepped up and replaced the tranny as long as I paid a portion of the labour cost. That was only a month ago so we'll see how we go from here.

mad hatter · Post by **mad hatter** » 02 May 2011, 13:50

kcodyjr wrote:"Look" good? That's nice, but hardly definitive.

Start it up and squirt some carburetor cleaner at the hoses, especially the ends. If the engine doesn't pick up a few RPM's, then the lines are good.

Before you go swapping out a TCV, cap/rotor/wires/plugs/filters are recent?

Good point on the vacuum lines. In my experiences with vacuum lines (i also have a VW Passat 1.8T - vacuum lines are a known common problem) the leaks were always due to visible damage. Never thought about the lines leaking at the fitting. I'll check it out. And the regular maintenance items are up to date so I should be good there.