Samurai 20V Posted April 18, 2018 Share Posted April 18, 2018 Hi Chaps. Have an issue on my TT6 BPU. On 6th gear mainly, when i floor the car below 3700rpm, get a low boost pressure, past the transition same boost. I have to come off the gas, then floor it again for it to boost normally. I had the issue before, it was a pinhole in the vac line to the IACV VSV. Checked the same two lines, one seemed very loose, replaced it. Car seems normal again. I pulled this hose again after about over an hour, the whoosh was very slight. Is this normal? How long does the pressure tank hold pressure once the car is parked up? Thanks. Quote Link to comment Share on other sites More sharing options...
auzzam Posted April 19, 2018 Share Posted April 19, 2018 I ended up just changing all my pipes and since then it's been a lot better. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted April 19, 2018 Share Posted April 19, 2018 It is normal for the pressure tank to store some pressure which you can hear when you disconnect a few select lines. Quote Link to comment Share on other sites More sharing options...
Scooter Posted April 19, 2018 Share Posted April 19, 2018 Loads of good info here..............there is a link a little way through to another thread re the sequential system and the Link pipes collapsing, if your link pipes (x2 accordion ones you can see from above) are possibly original I'd change these as a matter of course, they are like a 20 year service item! as are probably most of the pipes, but these collapse internally and new ones will 100% help/improve things even if they aren't the current cause. http://www.mkivsupra.net/vbb/showthread.php?271772-Is-my-pressure-tank-leaking&highlight=pressure+tank Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 19, 2018 Author Share Posted April 19, 2018 Thanks guys. Just for some history, 3 years ago, I changed all VSV's, vac pipes, link pipes, IACV, EGCV and BOV and pressure tank. Car has been perfect since then till now. I wasn't sure if the pressure tank bleeds it's pressure off after the car being parked for a while. The car is making its full boost, just this issue in sixth gear. Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 19, 2018 Author Share Posted April 19, 2018 It is normal for the pressure tank to store some pressure which you can hear when you disconnect a few select lines. Does it bleed some off after time? I remember if you disconnected those lines shortly after driving, you get a very loud whoosh. Quote Link to comment Share on other sites More sharing options...
Scooter Posted April 19, 2018 Share Posted April 19, 2018 Thanks guys. Just for some history, 3 years ago, I changed all VSV's, vac pipes, link pipes, IACV, EGCV and BOV and pressure tank. Can't be much left to be the culprit!! Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 19, 2018 Author Share Posted April 19, 2018 Can't be much left to be the culprit!! True.. Spent a lot of time fixing it the last time.. Car has been an animal since then.. Quote Link to comment Share on other sites More sharing options...
Scooter Posted April 19, 2018 Share Posted April 19, 2018 It's odd that it's only 6th? perhaps that's only where you notice it? Boost controller all ok if you have one? Quote Link to comment Share on other sites More sharing options...
Rob W Posted April 19, 2018 Share Posted April 19, 2018 To my understanding I thought the pressure tank only holds pressure in TTC mode, hence why if you trying to detect a vac line link you do the TTC mode to see if your system is holding? Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 19, 2018 Author Share Posted April 19, 2018 It's odd that it's only 6th? perhaps that's only where you notice it? Boost controller all ok if you have one? Yes mate, HKS EVC, working fine.. To my understanding I thought the pressure tank only holds pressure in TTC mode, hence why if you trying to detect a vac line link you do the TTC mode to see if your system is holding? Ah yes, you are correct Rob, I went back to the thread above that is true. I'm gonna drive the car with the replaced hose to confirm if the problem is gone, if not, will try TTC. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 20, 2018 Share Posted April 20, 2018 In theory it should hold pressure indefinitely, but osmosis and slightly imperfect pipe sealing will normally see them depleted overnight. Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 20, 2018 Author Share Posted April 20, 2018 In theory it should hold pressure indefinitely, but osmosis and slightly imperfect pipe sealing will normally see them depleted overnight. Ok, thanks Chris.. I will test drive the car this weekend to check if the issue disappeared after changing that pipe. Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted April 23, 2018 Author Share Posted April 23, 2018 Took the car for a long test drive, problem seems solved. It seems to be pulling harder than before.. Maybe this pipe has been leaking for a while. Thanks to all for the help. Quote Link to comment Share on other sites More sharing options...
snuf Posted May 5, 2018 Share Posted May 5, 2018 Hi I used a bicycle tyre pump with gauge to pressurise the vacuum system. I didn’t go past 12psi, as I am unsure of the max pressure what the system can take. Connect the pump to the steel pipe that is marked no 10 on the picture, then inflate to 12psi. Check the gauge to see how long it takes for the pressure to fall. Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted May 5, 2018 Author Share Posted May 5, 2018 Thanks for the advice. Car seems fine now, in fact, pulling harder than it ever did. The car used to fuel very heavy on 95 octane, AFR in the 8s.. Its now maxing at 9.5. I think this pipe has been an issue from a long time.. Quote Link to comment Share on other sites More sharing options...
meister_raul Posted May 6, 2018 Share Posted May 6, 2018 Hi I used a bicycle tyre pump with gauge to pressurise the vacuum system. I didn’t go past 12psi, as I am unsure of the max pressure what the system can take. Connect the pump to the steel pipe that is marked no 10 on the picture, then inflate to 12psi. Check the gauge to see how long it takes for the pressure to fall. Hi, what picture do you mean? I want to do this test because I am getting a similar problem, but in all gears (auto) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.