Hello all again,

I started to look for mods for this car and took it to Frank at Eurosport tuning in Mississauga, upon taking it for a short drive he felt that it runs smooth but it does not seem to have all the power it is supposed to.

I have replaced all vacuum lines, spark plugs, plug wires, distributor rotor and cap, air filter, lube oil and filter. I also replaced the fuel filter which seemed to give the most dramatic improvement. So I checked the fuel pressure and it sits at 28 psi at idle and when you "blip" the throttle it jumps to around 38 - 42 psi. I am thinking that the fuel pump is clogged because when I mash the throttle the boost jumps to 3/4 of the white area on the boost gauge but in 2-3 seconds later it drops to 1/2 the white area. I think that the reason for this is that the fuel pump cannot deliver enough fuel and the ecu detects a lean condition and then cuts boost. I asked my parts guy at the local dealership and he thinks that it may be a clogged catalytic converter. A replacement exhaust with a new cat is coming but it won't be in for a while.

Anyone have any other ideas?

Thanks!

 

That would make sense. Because otherwise if it was hitting fuel cut that would mean that it would be boosting to 15PSI, since that's where the ECU hits fuel cut, and if that was the case, that means your wastegate isn't operating for some reason or you have a major vac leak, but you said you replaced your vac lines.

 

very cool, is ther eanything in particular that I should be looking for? I checked the pressure on the schrader valve on the fuel rail, and underneath the car just before the fuel filter but it seems to sit around 40 psi and drops to around 30 psi when you blip the throttle.

 

Did you inspect all the intercooler hoses really good?
Sounds like you have a leak somewhere and the boost is bleeding off.
DO you have the 13g or 15T turbo?

 

I checked all the intercooler hoses carefully; besides some rusty clamps they all seem ok. I can connect an actual pressure gauge to get hard numbers for the boost if that would help. I was thinking of replacing all the hoses with silicone ones but before I start spending any money with mods I want to make sure that everything else is good. The car is completely stock so I guess that means it has a 15T turbo?
the car is a 95 850 turbo, completely stock. I have checked the compression and after the car is warm all cylinders are 155 - 160 psi.

if anyone has any other ideas what else it could be let me know.

Thanks!

 

I guess double check all your vac lines, make sure they're going to the right place and what not.

15G

 

I was very careful with the vacuum lines. I think that they may have been the original ones because they still had the colored tape on them. do you have a decent vacuum diagram for the 850 turbo around?

thanks!

 

I don't, but 850tony may seeing as how he's the king of diagrams.

 

should I just PM him then?

 

He's on right now, give him a day or so see if he chimes in, you can if you want to though.

 

cool, I have been casing this problem for a while now, it started with poor fuel economy and now I am just trying to get some of the oomph back, well trying to get some oomph. The car has never really been all that fast.h

 

FYI the 15G has boost fade normally. I have mine set at 14 PSI but after I hit 14 PSI it will drop to 10 PSI. That is pretty much normal.
Yes put a real gauge on there and see exactly what the numbers are.

 

ah cool,
ok I will give that a shot soon then, I have an emergency at work that I must attend to. I will check to see what the actual boost pressure is and get back to everyone.

Thanks again!

 

so I connected a pressure guage and it peaks at 9.5PSI for a couple of seconds and then drops to 4 -5 PSI. So yea there is no boost... LOL also seems to have more ***** when the turbo isn't spooling :P

 

Look at where the waste gate rod connects. See if the part the rod connects to walked up some.
If it has the gap like in the picture it did walk up and it need to be tapped down some.

 

Well the shaft is flat against the turbo. Are there any neat tricks to track down vacuum leaks?

 

Well I have made a special tool for checking for leaks.
https://volvoforums.com/forum/volvo-850-16/home-made-special-tool-18124/

 

brilliant! I think I might have a spare pressure regulator kicking around somewhere, all I need is to find something that will work well as a plug for the intake...

 

Remove the oil cap first and keep the pressure low. This way you do not blow any seals out.

 

I finally replaced the exhaust and leak tested the system. There are no leaks except for the weep hole in the bottom of the intercooler. I disconnected the hoses at the throttle body and at the turbo and the system was able to hold 25psi.

I also recently replaced turbo with a 16T. The reason I replaced the turbo is that I needed an angled flange for my exhaust and this one was rebuilt and a really good deal. I also replaced the BCS and cleaned the PTC.

I checked both the CBV and the wastegate actuator on the turbo before it was installed and the both worked perfectly.

I disconnected the vacuum line to the wastegate to try and figure out if it was leaking under pressure. I was careful not to allow the car to boost past 11 psi. All I can say is WOW, it is an entirely different car and I could not go past 1/3 throttle without the boost pressure jumping way beyond 11psi. I should also add that the dipstick popped out during this little test. I reattached the vacuum line to the BCS and it is back to its sluggish self.

So it looks like the car "can" boost but for some odd reason the BCS is not allowing it to. When I cleaned the PTC I noticed some rather new looking stickers on the hoses so I suspect that the PCV system may have been replaced recently.

so any more ideas?