Seagrams Posted January 25, 2008 Report Share Posted January 25, 2008 Ok ladies this isn't for the weak of heart; I've got a real humdinger of a problem here so put your reading glasses on and get a snack/cocktail.If any of you care to remember, I've had an ongoing boost problem (yes another boost issue post, but this ain't your typical problem). With my stock BCS, I cannot get more than 5 psi of boost in my 96 855R, Sometimes when i'm doing like 55+mph, i can get 7 psi but whatever, that's unacceptable. HOWEVER, when i have my MBC hooked up, I get 10+psi NO problem (actually when it's been real cold, i've hit fuel cut on occasion, i turned the boost down a kiss, no worries). Here is what i've done:Swapped in another BCS, same issue. (I realized that when i first put my new vac lines in roughly 8 or so months ago, i had my wastegate and compressor lines swapped, switching them back got me less boost than when i had them crossed, figured maybe i fubared the BCS, but a different one hasn't helped-i get the exact same thing.)New (ish under a year old) vac lines (all hooked up correctly) Samco IC hoses and i've done a boost leak test, so I know that as far as my charged air piping/intercooler goes, no leaks.Checked for shaft play in the turbo; there is none, nor any other shot turbo symptoms (smoke ect).Removed and inspected my CBV, it's in surprisingly good shape and holds vacuum fine; no leaks or problems there.Compression test good.Oil analysis AmazingTried tightening the wastegate, didn't really do much, just made the boost come on stronger.Before the addition of the MBC, disconnected the wastegate vac line, although i didn't take it higher than 11 psi, easily felt like i coulda kept pushing it up till the engine popped.Regular Maintenance always done, plus a little extra TLC for my swedish baby every now and again, I spoil her After all the partially clogged cat topics of late, I went to an exhaust shop today and had them check my cat. No rattles or other obvious signs of failure, it is however, running a bit colder than it should (but not enough to be causing this). No obvious dents, dings or holes in my exhaust that would restrict flow.Other than that, if it's been mentioned on this and other volvo sites as far as boost issues, I've either done it or been able to rule it out. I may be leaving something else out i've done, but as far as the "usual" suspects go, I've checked them off the list.SO wtf could it be? I have an idea or two but it just doesn't seem either are really the answer. Here they are:Cat COULD be starting to turn, but since it isn't completely malfunctioning yet, that can't be %100 of the issue but possibly could be a contributing factor. I say this because for the past 2 months or so, when driving the car cold and slowly accelerating (say from 25 to 30 mph over the course of 10 seconds) sometimes i notice for a second or two that the engine feel like it's suddenly under greater load, as if i were accelerating and suddenly someone hooked a trailer or something up to the car (or like there is an invisible hill) and then it disappears just as quickly.My other concern, after talking with a couple friends who are professional mechanics who've worked on Volvos is the EGR valve. I know the ECU's in these cars are great at compensating for slight issues without throwing DTC's. Getting the EGR out seems like something of a pita (especially cause it's not warm up here and nothing likes to work well in the cold, including me) but while i can see how this could hurt, I don't see how it could hurt to the tune of 5 psi Right now, I'm thinking that my next move will be to take it to my volvo guy's shop and throw the car on his dyno (the kind used for pre-OBDII emissions testing), stick the probe up the tailpipe and get a good readout of everything in my exhaust gases so i can see if i'm running rich, lean, or to give me ANY clue what's going on here without having to pull out my EGR and potentially not seeing anything overtly wrong, then douching the valve in carb cleaner overnight and not seeing any improvement.Just about everyone i've talked to agrees this is a real quandry. I've passed the point of being frustrated long ago, now i'm really just curious as to why this is happening; it defies all common knowledge i've accrued about my car and how car systems work in general. I don't want to end up replacing everything on the car before i find the one "AH HA" piece giving me this problem, Money's not that tight, but i'm looking to buy a house and have other expenses that, and i hate to say this, take more priority over making a running car preform up to my piddling standards.... It's funny, my volvo mech used to laugh at me for putting all this work into my car; he asks "what do you need that extra 5psi for." Well other than the fact that there should be NO reason for my car not to preform as it should, I always say, if you have to ask why..... then you just don't get it.I digress.... please, please HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Vivecka and I really need it.....Thanks guys, fire away Link to comment Share on other sites More sharing options...
turbor850 Posted January 25, 2008 Report Share Posted January 25, 2008 where did the second BCS come from ? was it verified to be working ? Link to comment Share on other sites More sharing options...
theForgottenone Posted January 25, 2008 Report Share Posted January 25, 2008 After all the partially clogged cat topics of late, I went to an exhaust shop today and had them check my cat. No rattles or other obvious signs of failure, it is however, running a bit colder than it should (but not enough to be causing this). No obvious dents, dings or holes in my exhaust that would restrict flow.Cat COULD be starting to turn, but since it isn't completely malfunctioning yet, that can't be %100 of the issue but possibly could be a contributing factor. I say this because for the past 2 months or so, when driving the car cold and slowly accelerating (say from 25 to 30 mph over the course of 10 seconds) sometimes i notice for a second or two that the engine feel like it's suddenly under greater load, as if i were accelerating and suddenly someone hooked a trailer or something up to the car (or like there is an invisible hill) and then it disappears just as quickly.How did the exhaust shop test to see if your cat was working properly? On my old car that didn't pass emission, I had a shop measure the temp of the cat after its been warmed up (using a probe and put it directly underneath the cat) and it read normal range. However, I took it to another shop who replace the cat and the car passed VIOLA.I remember another thread on here who another member had a boost issue (similar to your) but had check and replace everything. Turn out his cat was clogged. btw, why don't you throw that BCS away and keep the MBC setup? Link to comment Share on other sites More sharing options...
Oreo931 Posted January 25, 2008 Report Share Posted January 25, 2008 Have you read this thread before?: http://volvospeed.com/vs_forum/index.php?showtopic=30669 Link to comment Share on other sites More sharing options...
theForgottenone Posted January 25, 2008 Report Share Posted January 25, 2008 Have you read this thread before?: http://volvospeed.com/vs_forum/index.php?showtopic=30669Wouldn't apply as he regain boost (5psi) after putting in MBC instead of BCS. Link to comment Share on other sites More sharing options...
Oreo931 Posted January 25, 2008 Report Share Posted January 25, 2008 Wouldn't apply as he regain boost (5psi) after putting in MBC instead of BCS.It could still be leaking. Link to comment Share on other sites More sharing options...
Seagrams Posted January 25, 2008 Author Report Share Posted January 25, 2008 Interesting point, i bought the BCS used off a 97 855R (killed) but it had worked on that car. I know this is a weaker point in my scientific method, but what are the chances of two BCSs' from two different years, malfunctioning in exactly the same way? possible sure, probable, eh. I think i'm going to take one apart to see exactly how those stepper motors and seals/valves do their jobs, cause i haven't gotten a satisfactory answer on how it works precisely, and maybe try to douche the other one with cleaner.How did the exhaust shop test to see if your cat was working properly? On my old car that didn't pass emission, I had a shop measure the temp of the cat after its been warmed up (using a probe and put it directly underneath the cat) and it read normal range. However, I took it to another shop who replace the cat and the car passed VIOLA.I remember another thread on here who another member had a boost issue (similar to your) but had check and replace everything. Turn out his cat was clogged. btw, why don't you throw that BCS away and keep the MBC setup?They tested it same way i did a while back, with a laser temp. gun, but while i was just checked to see if pre cat temps on the pipe were NOT warmer than the post cat temps, which would be one way of indicating a clogged cat, they gunned it all over (lift having bastards) plus they would know more about the acceptable temp tolerances are than I. They also gave it a couple of taps to see if it rattled and it did not. My man said that it could be the cat starting to turn, but especially with the symptoms i'm having, it was almost certainly not the primary culprit. Link to comment Share on other sites More sharing options...
D s50r Posted January 25, 2008 Report Share Posted January 25, 2008 cat cat cat ohhh did i mention cat? dude you have a bad cat............ unbolt it from the turbo and power brake the car and look at your boost gauge..... Link to comment Share on other sites More sharing options...
theForgottenone Posted January 25, 2008 Report Share Posted January 25, 2008 Volvo BCS notorious for getting clogged and faulty (esp if its old).Mind as well put the MBC back as it provide better boost control and more responsive for your car anyway. Link to comment Share on other sites More sharing options...
Seagrams Posted January 25, 2008 Author Report Share Posted January 25, 2008 Have you read this thread before?: http://volvospeed.com/vs_forum/index.php?showtopic=30669yup. one of the first threads i read. Also, i don't want to ditch the BCS totally for a couple reasons: firstly, i get better mpg with the bcs (even with a light foot keeping it out of boost) and given snowy/icy/generally miserable conditions we get up here, boost as regulated solely by the MBC becomes a control issue, unless you want to spend a damn good while just getting up to 40. And i by that i mean long enough to have soccer moms glare at you from their minivans.... + it means something not kosher is going on in the car, and i just can't leave it at that (unless it costs mad cash american dollars longtime) Link to comment Share on other sites More sharing options...
laird Posted January 25, 2008 Report Share Posted January 25, 2008 Your ECU could be in limp mode. It will return to normal after a while. Mine did the same thing but I can't recall why.Your knock sensors may be malfunctioning, thus sending bad info to the ECU. Link to comment Share on other sites More sharing options...
Seagrams Posted January 25, 2008 Author Report Share Posted January 25, 2008 Your ECU could be in limp mode. It will return to normal after a while. Mine did the same thing but I can't recall why.Your knock sensors may be malfunctioning, thus sending bad info to the ECU.I reset the ECU a couple months ago....no change, there is a thread on it here somewhere... if my knock sensors were malfunctioning, wouldn't i be experiencing other problems than boost issue? The car runs rather nicely (minus of course the reason of the thread here). How many people have had knock sensor failures? Link to comment Share on other sites More sharing options...
socal850tuner Posted January 25, 2008 Report Share Posted January 25, 2008 sounds like what happened to me before my turbo began to go bad... Link to comment Share on other sites More sharing options...
Seagrams Posted January 25, 2008 Author Report Share Posted January 25, 2008 sounds like what happened to me before my turbo began to go bad... i read your thread, but the difference i think is that i can still boost no prob unless i'm using the bcs, but the turbo and related components seem to be fine like wine... that's why it's a real kick in the teeth.... As i said i have a couple ideas, but really need some input.....unless my car is haunted... Link to comment Share on other sites More sharing options...
Zulu Posted January 25, 2008 Report Share Posted January 25, 2008 You don't have a wideband on the car? Also, triple check the TB hose is tight...mine came loose (at the TB) after being fine for over a year and I was making 5lbs. Link to comment Share on other sites More sharing options...
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