1995 volvo 850 turbo

yellowpuulwater · Post by **yellowpuulwater** » 18 Jul 2008, 10:31

Hello...when i check my 850 with an OBD II, the car passes everytime but when i go to check all of the individual systems, 4 of them or so are not ready including HO2, evap system, and a few others. Can anyone explain to me what these systems are? also, my car seems to have a very sensitive side. It gets full boost from the turbo whenver it wants and for the past 4 weeks, i have been driving it with almost no boost at all. Then, all of a sudden, will get it back while im driving and it is an awkward feeling because i can feel the loss and regain of the turbo pressure. Does anyone have any idea as to why this is happening to me and what i can do to solve the problem??

thanks,
ypw

chuckcintron · Post by **chuckcintron** » 18 Jul 2008, 11:11

H02 is a heated oxygen sensor, and it monitors the exhaust gases for chemical composition, feeding back to the ECU for fuel trim adjustments. On a dual-sensor system (like our cars) the ECU compares the readings from the sensor before the catalytic converter to those of the sensor after the cat, to determine how good a job the cat is doing.

Evap system is what makes your fuel system as 'closed' as it can be; trapping gasoline fumes from leaking into the atmosphere, routing them to the intake manifold instead.

For your boost problem, first thing is to check every single hose to make sure none are split or loose.

-Chuck

yellowpuulwater · Post by **yellowpuulwater** » 27 Jul 2008, 09:08

hey...i managed to look last night at the engine to check for any cracked hoses. I found one that runs parallel to another hose both seem to be leading back into one larger hose under the wastegate on the right of the turbo if youre looking from the front of the car at the engine. I tried to follow the hose, it was darker outside, but the hose runs from the front of the engine behind the throttle body to the wastegate or somewhere near it. Could this cracked hose be the problem to my loss of boost ?

ypw.

Post by **MadeInJapan** » 27 Jul 2008, 09:42

That is part of your PCV system. Any of those that are leaking can cause loss of boost. I assume what's happening is that with heat (of for other conditions) the hose on each side of the crack were expanding and closing up the leak...but at other times it wasn't, thus your leak. You really need to change out your PCV sytem (includes the oil trap under the intake manifold) and it's quite a job. Most likely other hoses in the system are also on their way out. Plenty written here on how to do it....look in the repair database. The entire kit is less than $140 for your car from www.fcpgroton.com (sometimes cheaper if they are selling this on ebay- where they call it "breather system."). Make sure you get an intake manifold too as the manifold has to come out in order to get to the "black box" (breather box, oil separator/oil trap- some even call it a flame trap, but it's not) under there. The nipple (called the PTC) on the accordion hose that the two hoses attached to (which you mentioned) also needs to be cleaned and it's a bit of a hassle.
Good luck and let us know what you do.

yellowpuulwater · Post by **yellowpuulwater** » 27 Jul 2008, 14:28

wow...looks like i have a bunch of fixin and readin up to do but i thank you for the post...ill get on it right away and see what i can do...i really hope this fixes the problem because i cant stand not having boost pressure that i know is there...

thanks again,
ypw