Robzki Posted June 18, 2012 Share Posted June 18, 2012 Hi I'll try and keep this as short as possible. TT auto jspec. Bpu etc Background: Had the car for 4 years and has never really felt 'right'. I have fixed various problems with the sequential system including a faulty oem 'bov' and a few failed vac hoses. These fixes have improved things but I've still never really seen what all the fuss is with bpu. It seemed quick but not that quick. Occasionally it would surprise me how quick it was, mostly it feels a bit farty. Anyway, I don't drive the car much as the missus uses it as her daily. a month or so ago she said it seemed a bit flat and didn't pick up on the turbos as well as it used to. I ignored her obviously but after driving it yesterday it turns out that she is right(don't tell her). It boosts on the 1st turbo to 0.5 then a bit of a dip and then 0.7max on the second, but this comes on slowly. It really does seem slow. I had bought new vac hoses/bungs/silicone connectors last week and thought I would fit them yesterday to try and find the fault. some of the vac lines were a little loose and mostly pretty tough. I only changed the easy to get to ones as I was avoiding the rain. In one of the rushed trips out to the car I snapped a nipple off of the Intake Air Control Valve (IACV) Until I can get a new IACV I am forced into TTC, this has never interested me but realise it will help with the diagnosis of the ongoing fault. I finally got the car back together last night, so had limited testing.I am in no way an expert with the seq system so I apologise if I have got this all wrong. I took the car for a drive to to pressurise the system, after about 5 pulls where the turbos should be I got 0.3bar pretty much all the way up the revs. I kept going for a couple of miles and on the only hill in the area I could test it on. The car went off like a scalded cat at 4000rpm it had the slip control light working overtime at 60mph. Now I realise what all the fuss is about. I did this 3 times in quick succession and the turbos seemed to come on a bit earlier at around 3500rpm. I then had to slow down for a mile. I then had a good space to have a run but the car seemed slower and only hit full boost at 5000rpm I then left a longer gap(2 miles) before getting on the turbos and I then had 0.3bar again, several runs later I had full boost. Am I right in thinking that I have a leak on the pressure tank side? I seem to have to use the turbos 5-6times to pressurise the system to get things working. It seems to lose the ability to keep the actuators open after 3mins or so of slow driving. I haven't had a chance to pull a pipe to see if it is holding pressure but with my limited knowledge I assume that this would be the cause? I have researched a lot but haven't found anyone with the same issue Thanks for any help Rob Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 18, 2012 Share Posted June 18, 2012 (edited) that does sound like you have a leak somewhere, once you do the ttc if you park up and leave it a couple of minutes then take the pipe off the the second turbo acuator it should leak out the pressure if it does not the its leaking, there are vac pipe over both sides of the enginee make sure you change them all number 7 in this picture http://www.mkivsupra.net/vbb/attachment.php?attachmentid=13946&d=1112559170 Edited June 18, 2012 by mellonman (see edit history) Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 18, 2012 Author Share Posted June 18, 2012 Car arrived back this evening and 15mins after stopping, no pressure in the tank. I have just replaced some more hoses, I'm still working my way to the pressure tank ones I've just revved it a few times to try and pressurise the tank, after 5-6 revs to 4-5000rpm the actuator moves, it takes 2 revs to get it to fully open after it starts moving. If I then let it idle the actuator slowly retracts, possibly taking 2 minutes to fully retract while idling. I figure this is meant to stay fully open even if the car is stopped if the pressure tank is working? This is in ttc. would this cause the flaky unreliable operation while in sequential? Thanks for your help mellonman I assume you are the only mkivsupra.net technician on duty today. Rob Quote Link to comment Share on other sites More sharing options...
absz Posted June 18, 2012 Share Posted June 18, 2012 Might be a sticking actuator valve or possible leaking wastegate, Just my 2pence worth. Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 19, 2012 Share Posted June 19, 2012 (edited) Car arrived back this evening and 15mins after stopping, no pressure in the tank. I have just replaced some more hoses, I'm still working my way to the pressure tank ones I've just revved it a few times to try and pressurise the tank, after 5-6 revs to 4-5000rpm the actuator moves, it takes 2 revs to get it to fully open after it starts moving. If I then let it idle the actuator slowly retracts, possibly taking 2 minutes to fully retract while idling. I figure this is meant to stay fully open even if the car is stopped if the pressure tank is working? This is in ttc. would this cause the flaky unreliable operation while in sequential? Thanks for your help mellonman I assume you are the only mkivsupra.net technician on duty today. Rob you 100% have a leak then somewhere i think one of the pipes from the back of the block almost goes straight to the preassure tank then to that vsv but they are linked so could be else where or even a vsv sticking this picture will help you follow what to check Edited June 19, 2012 by mellonman (see edit history) Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 19, 2012 Author Share Posted June 19, 2012 Thanks I'll keep changing vac pipes which will hopefully eliminate the pressure tank itself as I don't fancy changing that. Even the vac pipes on either side of the block look near impossible to get to. Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 19, 2012 Share Posted June 19, 2012 i know mate some at the very back of the block you pritty much have to take some of the turbo piping off to get too, but remember you dont have to just replace you can preasurerise the system to help you find your leak, and disconect vac pipes and block them to help pin point, you might get away with a foot pump to pressurise the system but will be next to impossibly to do on your own Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted June 20, 2012 Share Posted June 20, 2012 Pressure tank hoses are a bitch to get at! Took me 2 hours to get them off and none looked split! Going to try a new IACV as it's easier to change than the pressure tank! Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 20, 2012 Author Share Posted June 20, 2012 Pressure tank hoses are a bitch to get at! Took me 2 hours to get them off and none looked split! Going to try a new IACV as it's easier to change than the pressure tank! I know what you mean. I can get my hand to them just, but I too have fat fingers so I'm going to have to remove some things to get better access. Have you got a price for a new iac vsv? As I still need one and not having much luck finding one s/h Have you gone ttc as this would remove the iac vsv from the equation if I understand it properly? In ttc I hit well over 1 bar, peaked at 1.5bar So I'm assuming it can only be an actuator, pressure tank or vac pipes, but theres not a lot of advice coming from here Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 20, 2012 Share Posted June 20, 2012 sorry to say guys but there is no easy way, there is the ways i have said and thats it really so no body can help anymore to be fair. 1.replace all vac hoses 2.preasurise the system to help pin point you leak 3.replace parts. robzki because you are loosing your preasure after you have gone ttc,I would say you 99% have a leak, now you have to find it so you need to preasurise sections of the vac system and find where it is. Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 20, 2012 Author Share Posted June 20, 2012 sorry to say guys but there is no easy way, there is the ways i have said and thats it really so no body can help anymore to be fair. robzki because you are loosing your preasure after you have gone ttc,I would say you 99% have a leak, now you have to find it so you need to preasurise sections of the vac system and find where it is. Thanks, I just wanted a shoulder to cry on Your way sounds sensible, I'm going to rig up something at the weekend to pressurise the system( 10psi?) and listen for leaks. I don't really want to change the pressure tank hoses if they are ok, as I think it is best left alone if the leak isn't there. Thanks again Rob Quote Link to comment Share on other sites More sharing options...
mwilkinson Posted June 20, 2012 Share Posted June 20, 2012 Rob, I have a spare working pressure tank and various valves off my car if you need them. Just let me know if you want tem and I will send them to you. My car is 1995 J-spec TT. Matt Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 20, 2012 Author Share Posted June 20, 2012 IACV IACV IACV I'll pm later. Rob Quote Link to comment Share on other sites More sharing options...
mwilkinson Posted June 20, 2012 Share Posted June 20, 2012 IACV IACV IACV I'll pm later. Rob If we are talking the IACV VSV then yes (the small valve on top of engine with two vac feeds). The actual IACV is being used for my single build. PM me and I will get the bits out to you. Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted June 21, 2012 Share Posted June 21, 2012 Rob, I spoke to Steve Manley yesterday and he said there was some stocking the UK of IACV VSV's. Was meant to be getting one posted yesterday if it got to him in time. £90 posted, give or take a couple of quid. I replaced the 4 vac hoses behind the block yesterday too (2 on turbo side and 2 off the pressure tank). Seems it might have made a difference but not sure if that's a placebo or because I haven't driven the car all week. Thing with mine is the problem is intermittent so hard to tell if it's fixed. When the turbo's are spinning everything seems fine, but sometimes the 1st one boosts a bit low and the second doesn't come online unless I lift and put my foot down again, then it goes like stink! Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 21, 2012 Share Posted June 21, 2012 (edited) Rob, I spoke to Steve Manley yesterday and he said there was some stocking the UK of IACV VSV's. Was meant to be getting one posted yesterday if it got to him in time. £90 posted, give or take a couple of quid. I replaced the 4 vac hoses behind the block yesterday too (2 on turbo side and 2 off the pressure tank). Seems it might have made a difference but not sure if that's a placebo or because I haven't driven the car all week. Thing with mine is the problem is intermittent so hard to tell if it's fixed. When the turbo's are spinning everything seems fine, but sometimes the 1st one boosts a bit low and the second doesn't come online unless I lift and put my foot down again, then it goes like stink! yours is not a vac pipe or leak.http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system its also good to check the corragated turbo pipeing as they colapse closed on the inside and you cant tell unless taking apart and looking Edited June 21, 2012 by mellonman (see edit history) Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 21, 2012 Author Share Posted June 21, 2012 Rob, I spoke to Steve Manley yesterday and he said there was some stocking the UK of IACV VSV's. Was meant to be getting one posted yesterday if it got to him in time. £90 posted, give or take a couple of quid. I replaced the 4 vac hoses behind the block yesterday too (2 on turbo side and 2 off the pressure tank). Seems it might have made a difference but not sure if that's a placebo or because I haven't driven the car all week. Thing with mine is the problem is intermittent so hard to tell if it's fixed. When the turbo's are spinning everything seems fine, but sometimes the 1st one boosts a bit low and the second doesn't come online unless I lift and put my foot down again, then it goes like stink! Have you tried TTC? as mine was kind of like your symptoms for a while now, but whatever has been causing it has got worse. In ttc it is boosting fine but the system isn't holding pressure. So can't maintain ttc. I'm figuring that I have a hose that has had a split for a while so sometimes it has been sealed and others not depending how hard I've driven it before testing the boost. If you don't want to try TTC then just give it wot a few times to see whether you have a leak and overcome it by pressurising the system a few times. Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 22, 2012 Author Share Posted June 22, 2012 Just a quick one, but in ttc I didn't hear any(much) change in the exhaust note. I've just had a check and when I rev it at idle a few times....... The iacv(the one at the top of the engine near the bulkhead?) moves open and stays there even at idle. The egcv(the one that can easily be seen from the drivers side, in between the turbos that sits on top of the 1st decat?) doesn't move at all I was under the impression that these both open at around the same pressure? What would be the affects of the egcv not opening at all? I thought that they both shared the same pressure from the tank so naively thought that they would both just open at the same time. When I remove the pipe from the iacv vsv I can now hear air escape 5 mins after switching off. Any advice welcome as I'm now at a loss. Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 22, 2012 Author Share Posted June 22, 2012 (edited) I am also seeing conflicting info as to where you carry out the ttc mod. They all keep referring to doing the mod at the egcv vsv. I thought that it was done on the front one of the 2 the egbv(the one that goes to no1 turbo wategate) Here is an example on supraforums, 1 of many: "So, I put the car in TTC mode via the hose swapping method at the IACV VSV location and the EGCV VSV location" Even one of the guides I have seen has the pipes/vsvs mis labelled Edited June 22, 2012 by Robzki (see edit history) Quote Link to comment Share on other sites More sharing options...
Robzki Posted June 23, 2012 Author Share Posted June 23, 2012 Oh, that makes more sense, thanks a lot. Quote Link to comment Share on other sites More sharing options...
meister_raul Posted May 6, 2018 Share Posted May 6, 2018 So did you figured out? I am facing about the same problem...Changed all the "easy" vacuum lines, checked all vsv, all good 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.