Turbo5cyl Posted February 1, 2017 Report Share Posted February 1, 2017 Hi everyone, I am having an issue with my (manual m66) 04 s60r . I bought it a few months ago and recently put a boost gauge in it. Ever since then, I see the car will only hold 10 psi under WOT. The car doesn't feel slower than before or slow at all, it just really bugs me knowing that I am missing out on a third of STOCK pressure (my understanding is 15psi is about stock). The car has 282000 kms or 175000 miles and is not modified. Luckily I have VIDA to help me out here but I am still stumped. I have cleaned both the MAF and the BPS and tried a friend's TCV as well, no improvements. If I unplug the TCV, i see about 6-7psi of boost so I assume the WG is set about right. I have tried turning it up a few turns as well just to see and no difference, just spikes a bit more. It will spike to about 12 psi but never maintain that....I used VIDA to see what the BPS is reading and it's maybe 1 psi different from the gauge so I don't think that's the issue. The MAF reads a little higher at idle than VIDA says is normal (16kg/h vs 14kg/hr), would that have ANYTHING to do with the boost pressure? I put in a MBC for a few pulls as well just to see if I can even get 15 psi and it was no problem at all. Even if I reset the ecu, i won't see anything above 10 psi. Does anybody ave any idea what is wrong and what I am missing? Any help at all would be great because I don't see why I don't have full boost.... Also I have tried to check for other threads on this topic but they all seems to just die and never resolve or no post about it being resolved. Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted February 1, 2017 Report Share Posted February 1, 2017 I think it would be important to not assume the waste gate is adjusted correctly. I ran into a similar situation with my R and had to tinker with the WG before getting it back to stock spec after checking things like BPS, air leaks etc. Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 1, 2017 Author Report Share Posted February 1, 2017 Ok, could I be getting lower boost if it was set too high? I thought the only thing that would happen is a big unwanted spike on spool up. How can I properly adjust it? Unplug the tcv and tinker till I see a certain pressure or is there another way? The way setting it is described in Vida seems so overly complicated and I don't have the special tool they use either. Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted February 1, 2017 Report Share Posted February 1, 2017 I use a cooling system pressure tester to adjust waste gates. Typically if a waste gate is set too high you will get a big boost spike and then it will settle below normal. I remove the vacuum line to the waste gate and pump the pressure tester up until the wast gate just moves. You may need to make several adjustments and then test drive to see where your at. Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 1, 2017 Author Report Share Posted February 1, 2017 Ok I will definitely take a look at that then. What pressure am I looking for when it just moves? I've read others say between 6 and 8 psi. What did you set yours too when it worked or what should it be? Link to comment Share on other sites More sharing options...
hootie6828 Posted February 2, 2017 Report Share Posted February 2, 2017 11 hours ago, Ihatespeedbumps said: I use a cooling system pressure tester to adjust waste gates. Typically if a waste gate is set too high you will get a big boost spike and then it will settle below normal. I remove the vacuum line to the waste gate and pump the pressure tester up until the wast gate just moves. You may need to make several adjustments and then test drive to see where your at. Would you be willing to elaborate on your exact test procedure? Where do you hook the pressure tester to, and what values are you looking for? Link to comment Share on other sites More sharing options...
NEU Posted February 2, 2017 Report Share Posted February 2, 2017 2 hours ago, hootie6828 said: Would you be willing to elaborate on your exact test procedure? Where do you hook the pressure tester to, and what values are you looking for? You hook the gauge up to your wastegate. There is only one connection to it. And the setting depends on your turbo. If you Google there is a chart and a How to video by IPD. Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 3, 2017 Author Report Share Posted February 3, 2017 So I tired adjusting the WG tonight and still 10 psi.... I watched that IPD video and at the end, I see it had listed the R engine as 4.4 psi for the WG setting. I set it to that with my compressor and a spare boost gauge i had laying around. The arm just starts to move at 4.4 psi. I reset the ecu after as well. Anybody else with an idea, please tell me what you think. Is it possible that somehow the ecu is programmed for 10 psi rather than 15? can I reprogram it to stock with VIDA in any way myself? Link to comment Share on other sites More sharing options...
Midnight Caller Posted February 3, 2017 Report Share Posted February 3, 2017 Did you check the CBV for leaks ? Your pressure issue might be because of a cracked compressor bypass valve (it's bolted in 3 screws on the turbo housing). Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 3, 2017 Author Report Share Posted February 3, 2017 No I haven't cause it looks like a nightmare to get too. If I can run 15 psi with a MBC, wouldn't that rule that out? Is there a way to check it without taking it all apart? Link to comment Share on other sites More sharing options...
Midnight Caller Posted February 3, 2017 Report Share Posted February 3, 2017 I checked it by hooking up the boost gauge to it, rather than to the intake manifold. But mind you I have an external blow off valve so I had no turbo surge when lifting the throttle. If you accelerate hard and the gauge needle registers pressure, you have leaks in your CBV. That valve should only act on vacuum, when lifting the throttle. I don't know if it's the most orthodox way of checking it without dismantling, but as they say, it worked for me. I've put a blanking plate on it after this so no more trouble. Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 3, 2017 Author Report Share Posted February 3, 2017 Hmm maybe I'll take it apart then since I don't want to have the turbo surging a bunch of times on a 280000 kms car. Another thing I should mention is that I notice sometimes under moderate throttle (where there should be a few psi boost), the car will jump to 0 psi (atmospheric pressure) and then have a lag of a second or two and then shoot up to like 5-6 psi instantaneously without me changing the throttle amount. Could that be because of a leaky CBV? Vad ca esti din Rominia, si eu la fel haha. Link to comment Share on other sites More sharing options...
Midnight Caller Posted February 5, 2017 Report Share Posted February 5, 2017 :)). Yes, I am from România but I must obey the forum rules so I'm writing in English. If the boost acts like that under part throttle, did you try replacing the TCV? The turbo control valve. Never mind that, I see you already tried it. Link to comment Share on other sites More sharing options...
Turbo5cyl Posted February 7, 2017 Author Report Share Posted February 7, 2017 Oh I did not know about that rule, sorry! Ok, i tested the CBV tonight. i unplugged it from the intake manifold (where my boost gauge is teed into) and applied vacuum to the line with my mouth and then put my tongue over the line, I waited a while and it the line was still under vacuum so I highly doubt it is leaking at all. I can hear it opening and closing if I create a large enough vacuum with my mouth (not too easy but definitely doable). I noticed today when driving the lack of boost under load and then an instantaneous spike to like 6 psi or so without change in throttle position. What could be causing this? Maybe that is causing my low boost issue too. Could it have something to do with throttle body? For example it opens to say 30% and then jumps to 50% open (and therefore building boost) for some reason? If it helps, the car is quite bad on fuel too, I see about 450-500 kms from a full tank which is about 13.3l/100 kms or 18mpg..... Link to comment Share on other sites More sharing options...
Midnight Caller Posted February 7, 2017 Report Share Posted February 7, 2017 Are you sure your MAF is good ? The throttle flap opens on pedal request so if you keep a steady foot, it shouldn't move. You should feel the car pulling then stalling, then pulling again if the throttle body is acting up on you. Link to comment Share on other sites More sharing options...
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