Seagrams Posted February 24, 2008 Author Report Share Posted February 24, 2008 Ok Gents Update time...Decided to take advantage of the lovely weather we're having today, I cleaned the MAF, it was a bit dirty, car feels like it pulls a bit harder now but no real change in boost pressure with the BCS. Just a moment ago, i unbolted the downpipe, pulled it off like 1/2-1/4 inch and took it for a ride. Asides from it sounding like a harley, again no change in my boost pressure. 5psi from a dig, 6psi from lik2 25-35 mph, climbs right up to 8psi or so in the 40-45 mph range and then falls off to 5/6psi at maybe 3500 rpm and holds it to red line, and anything 55/60+mph it boosts right up to 10psi and holds it (it did this before). So it's not my cat/exhaust or MAF and once again i'm stumped . The only other thing i can think of is to maybe get a good pressure gauge and pressure test the CBV (i only vacuum tested it and it held pretty well, does it matter if i pressure test it as well?) and While i'm at it i'll probably test the base setting of my wastegate but that's not really affecting my issue, (tightening it doesn't help) but as long as i'm in there you know....This is frustrating, Ideas? :rolleyes: Link to comment Share on other sites More sharing options...
sconeman Posted February 25, 2008 Report Share Posted February 25, 2008 This is frustrating, Ideas? Quickbricks is back in business and sells CBV repair kits for $45. I haven't done mine yet but I finally got all the parts. Link to comment Share on other sites More sharing options...
Seagrams Posted February 25, 2008 Author Report Share Posted February 25, 2008 Quickbricks is back in business and sells CBV repair kits for $45. I haven't done mine yet but I finally got all the parts.yea i've been tempted, but after vacuum testing the CBV i found it to be holding pretty well, so no leaks there to speak of. Would pressure cause leaks to show up that you wouldn't necessarily see while applying vacuum? I'd hate to go through their archaic ordering process only to have the part arrive and not see any difference.let me know what happens when you put yours on sconeman. Link to comment Share on other sites More sharing options...
lookforjoe Posted February 25, 2008 Report Share Posted February 25, 2008 Ok Gents Update time...Decided to take advantage of the lovely weather we're having today, I cleaned the MAF, it was a bit dirty, car feels like it pulls a bit harder now but no real change in boost pressure with the BCS. Just a moment ago, i unbolted the downpipe, pulled it off like 1/2-1/4 inch and took it for a ride. Asides from it sounding like a harley, again no change in my boost pressure. 5psi from a dig, 6psi from lik2 25-35 mph, climbs right up to 8psi or so in the 40-45 mph range and then falls off to 5/6psi at maybe 3500 rpm and holds it to red line, and anything 55/60+mph it boosts right up to 10psi and holds it (it did this before). So it's not my cat/exhaust or MAF and once again i'm stumped . The only other thing i can think of is to maybe get a good pressure gauge and pressure test the CBV (i only vacuum tested it and it held pretty well, does it matter if i pressure test it as well?) and While i'm at it i'll probably test the base setting of my wastegate but that's not really affecting my issue, (tightening it doesn't help) but as long as i'm in there you know....This is frustrating, Ideas? 1/2 gap should be enough to drop backpressure in compensation for a exhaust restriction - but you're saying the performance was identical? Is the boost curve normal for an 850 - I don't understand why you're seeing a drop @ 3500, unless another input is determining a reason to protect.Since the car can produce 10psi (normal cap for 850 R?) it seems that something else is limiting the system - offhand I don't recall what input parameters other than the MAF & the knock sensors contribute to overall boost level.If the CBV isn't leaking @ 10psi, it seems unlikely to be the issue when @ lower boost pressures. It can hold vacuum & still leak under pressure - where the CBV mates to the turbo casing. If the diaphragm is actually torn you shouldn't get any vacuum held on the vacuum port, or it will drop off depending on the level of rupture - since the diaphragm is layered it may be bleeding from one spot on one side to another spot on the other - that's what mine was doing. Link to comment Share on other sites More sharing options...
sconeman Posted February 25, 2008 Report Share Posted February 25, 2008 If the CBV isn't leaking @ 10psi, it seems unlikely to be the issue when @ lower boost pressures. It can hold vacuum & still leak under pressure - where the CBV mates to the turbo casing. If the diaphragm is actually torn you shouldn't get any vacuum held on the vacuum port, or it will drop off depending on the level of rupture - since the diaphragm is layered it may be bleeding from one spot on one side to another spot on the other - that's what mine was doing.Hey Lookforjoe,Is it possible to clean that mating area without taking the turbo off? If so how would you do it? In the pics you posted it looked like you had the turbo sitting on your workbench.On my car there is a little grease and crud that looks like it's gotten, very gradually, blown out of the top (north side) of the mating area. The crud is right behind a very small lip of the cbv plate and on top of the housing. Does this sound like a sign of leakage to you? Link to comment Share on other sites More sharing options...
Seagrams Posted February 25, 2008 Author Report Share Posted February 25, 2008 If your engine bay looks anything like mine, there's crud all over that mofo. I'd imagine you'd clean it the same way you would with the turbo out of the car; Lookforjoe suggested taking one of those scouring pads and some light grade oil (or regular engine oil i guess would work) and cleaning it that way. Leaving the turbo in the car just means you have less space to work but tight spaces are par for the course when you're working on these cars. Volvo's are built by Swedish elves with tiny hands :lol: Link to comment Share on other sites More sharing options...
sconeman Posted February 25, 2008 Report Share Posted February 25, 2008 If your engine bay looks anything like mine, there's crud all over that mofo. I'd imagine you'd clean it the same way you would with the turbo out of the car; Lookforjoe suggested taking one of those scouring pads and some light grade oil (or regular engine oil i guess would work) and cleaning it that way. Leaving the turbo in the car just means you have less space to work but tight spaces are par for the course when you're working on these cars. Volvo's are built by Swedish elves with tiny hands :lol:Yeah that is one tight space ! Elves definately. Can you think of any type of light adhesive that would help seal it up? Link to comment Share on other sites More sharing options...
Seagrams Posted February 26, 2008 Author Report Share Posted February 26, 2008 Yeah that is one tight space ! Elves definately. Can you think of any type of light adhesive that would help seal it up?seal up the housing? you don't want or need to do that. The diaphragm creates all the seal you need. There is no reason to seal the housing to the turbo, in fact i wouldn't do it. But being the lazy a*s that i am, if you WERE to seal it, use the same high temp silicon sealant people use on their blanking plates. (you can prolly find it on QBM's website under their blanking plate install instructions), but again I'd advise against it. Link to comment Share on other sites More sharing options...
flaco Posted February 26, 2008 Report Share Posted February 26, 2008 Ok I havent read ALL the replies, but here are some (obvious) thoughts:If with the wastegate hose disconnected you get 11+psi like you say, then there are no (or minor) leakscat CAN'T BE BADYou said the test light flashes when connected to the control valve: that means your ECU is lowering the pressure by activating the valve. As to why is the ECU dropping the pressure.... Could be your knock sensors, if so, it could be the sensors, something else causing knocking (for example dirty injectors causing lean mixtures - knocking), wiring probs (wasn't there a wiring update for the knock sensors?) or something else. Maybe an old O2 sensor saying mixture is lean thus causing the ecu to lower boost?If I were you, I'd try to test your car with another cars' ECU... Link to comment Share on other sites More sharing options...
lookforjoe Posted February 26, 2008 Report Share Posted February 26, 2008 Hey Lookforjoe,Is it possible to clean that mating area without taking the turbo off? If so how would you do it? In the pics you posted it looked like you had the turbo sitting on your workbench.On my car there is a little grease and crud that looks like it's gotten, very gradually, blown out of the top (north side) of the mating area. The crud is right behind a very small lip of the cbv plate and on top of the housing. Does this sound like a sign of leakage to you?Sure does.You can get the CBV off & clean the surface with it on the car - it's easier if you remove the short outlet hose, and of course the inlet bellows. As long as you have a short racheting 10mm wrench, it's not too bad. Link to comment Share on other sites More sharing options...
rsleepr88 Posted February 26, 2008 Report Share Posted February 26, 2008 alright, i have had this problem on numerous customers cars. if you have the original 15g on your car, where the wastegate shaft goes down into the exhast housing, there is a rollpin that holds it in place. what happens is the rollpin breaks and the wastegate shaft starts to walk up out of the turbo and then the flapper valve doesnt line up inside the exhaust housing and boost bleeds off thru the exhaust. there is two ways to check this. 1) look either under the car or with a mirror at the base of where the shaft goes down into the exhaust housing and if this is happening, you should be able to see where the shaft has walked up. or, 2) unbolt the dp and look inside the turbo and see if the flapper valve is covering the wastegate hole completly...i can almost guarantee this is your problem as i have fixed lots of these with this problem...hope this helps.btw: the shaft i am talking about in case there is a question is the part that your wastegate actuator hooks up to. Link to comment Share on other sites More sharing options...
sconeman Posted February 26, 2008 Report Share Posted February 26, 2008 ..i can almost guarantee this is your problem as i have fixed lots of these with this problem...hope this helps.btw: the shaft i am talking about in case there is a question is the part that your wastegate actuator hooks up to.on my car I was hoping that was the problem but alas it wasn't. As for seagrams....? Link to comment Share on other sites More sharing options...
rsleepr88 Posted February 26, 2008 Report Share Posted February 26, 2008 on my car I was hoping that was the problem but alas it wasn't. As for seagrams....?are you sure we are talking about the same thing?? not the wastegate actuator but the wastegate valve inside the exhaust housing on the turbo...also, have seen the seat that the wastegate valve seals against inside the exhaust housing crack and break again causing a boost leak but that is an extreme case not usually seen. Link to comment Share on other sites More sharing options...
flaco Posted February 26, 2008 Report Share Posted February 26, 2008 alright, i have had this problem on numerous customers cars. if you have the original 15g on your car, where the wastegate shaft goes down into the exhast housing, there is a rollpin that holds it in place. what happens is the rollpin breaks and the wastegate shaft starts to walk up out of the turbo and then the flapper valve doesnt line up inside the exhaust housing and boost bleeds off thru the exhaust. there is two ways to check this. 1) look either under the car or with a mirror at the base of where the shaft goes down into the exhaust housing and if this is happening, you should be able to see where the shaft has walked up. or, 2) unbolt the dp and look inside the turbo and see if the flapper valve is covering the wastegate hole completly...i can almost guarantee this is your problem as i have fixed lots of these with this problem...hope this helps.btw: the shaft i am talking about in case there is a question is the part that your wastegate actuator hooks up to.I agree this is a symptom, BUT if this was his case, then he should be able to adjust the base wastegate setting by shortening the rod. I recall somewhere in page 2-3-4 he mentioned he already tried changing the rod, and that peak boost was still the same, it just hit early/harder. Therefore, it is still the ECU dropping boost more than it should. Link to comment Share on other sites More sharing options...
rsleepr88 Posted February 26, 2008 Report Share Posted February 26, 2008 I agree this is a symptom, BUT if this was his case, then he should be able to adjust the base wastegate setting by shortening the rod. I recall somewhere in page 2-3-4 he mentioned he already tried changing the rod, and that peak boost was still the same, it just hit early/harder. Therefore, it is still the ECU dropping boost more than it should.im not talking about the actuator rod, im talking about the shaft that goes down thru the turbocharger housing and connects to the wastegate inside the exhaust housing...if anyone has a turbo loose off a car, look into the exhaust side of it and you will see the wastegate valve. the byproduct of the shaft walking up out of the exhaust housing is the valve no longer aligns with the hole therefore bleeding off boost. the turbo will still boost, but will build boost very slowly depending on how bad this problem is. Link to comment Share on other sites More sharing options...
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