Guest CombatSanta Posted July 10, 2014 Share Posted July 10, 2014 (edited) I have got a problem with the boost in my car. Sometimes when I floor it from let's say 2000 rpm the boost only goes up to 0.2-0.3 and stays there. If I let off the gas pedal and floor it again one or two times the boost will come in at a healthy 0.7 bar. This only happens about half of the time though. Sometimes the boost will come directly as it should. The last few times this fault occured, and I only got 0.3 bar, I kept my foot down and the boost came at around 3800rpm and went to 1.0 bar but the transition when the no2 turbo kicked in was very twitchy. It seems to be a fault with something responsable for spooling or keeping boost from the no 1 turbo. Does anyone have any experience with this boost behaviour? Any ideas what it could be? Sticky vsv? Sticky wastegate? Vaccum leak? Thanks in advance. ----------------------------------------------------------------------------------------- Hi, I just wanted to say that I solved the problem. I replaced all the easy and semi easy to get to hoses, tested and cleaned the connections for the EGBV and IACV VSVs. Now I get 0.7 bar everytime from 2000rpm and 1.0 when the second turbo kicks in. Why I get 1.0 is a bit of a mystery though, because I completely disconnected my EBC.... Anyway, thanks for the help! Edited July 17, 2014 by CombatSanta (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 11, 2014 Share Posted July 11, 2014 Probably a vacuum / pressure leak on the small bore hoses for the sequential control system. Use high quality rubber hose like the original, *NOT* coloured silicone hose, or even worse silicone hose held on with tie wraps as it's such a poor fit it needs them to even briefly stay in place. Silicone hose for this purpose is as sensible as greasing your brake pads. Show me a F1 or Le Mans Prototype engine that uses it.... Don't forget the ones to the pressure tank that run behind the engine! If a hose change doesn't fix it I would look towards a laky or sticky VSV. It's HIGHLY unlikely to be a wastegate issue. I would especially look to change the hoses to the pressure tank, but get them on the right way. If you cross them it won't sequence at all. Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted July 11, 2014 Share Posted July 11, 2014 I have this same issue, probably the VSV if its on and off. Refer to these threads http://www.mkivsupra.net/vbb/showthread.php?35924-Sequential-turbo-hoses http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system Quote Link to comment Share on other sites More sharing options...
Guest CombatSanta Posted July 11, 2014 Share Posted July 11, 2014 Thanks Chris for the reply. I will definitely check the hoses to the pressure tank. And every other vacuum hose I can find. I will report back when I find the problem. Quote Link to comment Share on other sites More sharing options...
Guest CombatSanta Posted July 11, 2014 Share Posted July 11, 2014 I have this same issue, probably the VSV if its on and off. Refer to these threads http://www.mkivsupra.net/vbb/showthread.php?35924-Sequential-turbo-hoses http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system Thanks for the reply. So you still have the problem on your car? Will you let me know if you find the fault? I will check all the hoses as Chris said, but it could be a VSV as you said. When you say VSV, which one do you mean? Reading one of the threads you posted suggests the EGBV as it seems to be the only one responsible for pressure in the No 1 turbo. I found this and I will try to check them all. http://wilbo666.pbworks.com/w/page/65646659/2JZ-GTE%20Sequential%20Turbo%20System Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted July 11, 2014 Share Posted July 11, 2014 Thanks for the reply. So you still have the problem on your car? Will you let me know if you find the fault? I will check all the hoses as Chris said, but it could be a VSV as you said. When you say VSV, which one do you mean? Reading one of the threads you posted suggests the EGBV as it seems to be the only one responsible for pressure in the No 1 turbo. I found this and I will try to check them all. http://wilbo666.pbworks.com/w/page/65646659/2JZ-GTE%20Sequential%20Turbo%20System I believe I have resolved mine..... It was a connection issue into the intake air control value vsv I broke the clip a while ago and it must of not had a good contact hence the intermittent issue, i just used elec tape on it but cleaned it with some elec connection cleaning solution Quote Link to comment Share on other sites More sharing options...
gordy.r Posted July 11, 2014 Share Posted July 11, 2014 I have this exact same issue as well! I've not fully (or even attempted to) investigate it yet as it is so intermittent. Good thread to keep an eye on though! * on a side note, Chirs Wilson, would you recommend replacing the twin turbo link pipes with silicone pipes or stick with OEM pipes? (Sorry for the hijack OP) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 11, 2014 Share Posted July 11, 2014 The dual wall, concertina stock pipes seem to de-laminate badly with age, so by all means try silicone hose. In larger ID's it's fine, if of good quality. It's the small bore stuff with no fabric mesh in the moulding that's rubbish. It splits along its length for fun, and is nothing like as secure as "rubber" hose of the right size. Quote Link to comment Share on other sites More sharing options...
gordy.r Posted July 11, 2014 Share Posted July 11, 2014 Cheers again Chris, helpful as always! Quote Link to comment Share on other sites More sharing options...
ScottC Posted July 12, 2014 Share Posted July 12, 2014 Probably a vacuum / pressure leak on the small bore hoses for the sequential control system. Use high quality rubber hose like the original. Any recommendations on makes of hose Chris, and do you know the bore size? Quote Link to comment Share on other sites More sharing options...
Guest CombatSanta Posted July 17, 2014 Share Posted July 17, 2014 SOLVED! Read first post. Quote Link to comment Share on other sites More sharing options...
Guest CombatSanta Posted July 18, 2014 Share Posted July 18, 2014 I believe I have resolved mine..... It was a connection issue into the intake air control value vsv I broke the clip a while ago and it must of not had a good contact hence the intermittent issue, i just used elec tape on it but cleaned it with some elec connection cleaning solution http://www.mkivsupra.net/vbb/attachment.php?attachmentid=13935&d=1111617575 ' Come to think of it, my locking clip on the connector for the IACV was also broken so I used a strap to hold it in place. Maybe that was what fixed it. Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted July 18, 2014 Share Posted July 18, 2014 thats what fixed mine Quote Link to comment Share on other sites More sharing options...
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