Tricky-Ricky Posted October 30, 2006 Share Posted October 30, 2006 Well it looks like i will have to either sort or fudge my boost problems! my original problem was only getting .8 bar after full decat, initially had a seized second turbo but after replacement it was still .8 bar! so tested all VSVs and the actuators, all fine, so i went to TTC mode, still .8 bar:blink: so i ended up taking everything out of the equation, and ended up running off just the two waste gates, which got me 1.2-1.25 so i was happy, but with the advent of cooler weather i am now getting 1.3 -1.4 bar:( so i have reconnected just one VSV and got .8 -.9 bar, and i can see little hope of getting to the bottom of it! so should i now get myself a flash boost controller so i can take it up to 1.0 - 1.2 bar or just be frugal and get a bleed valve and use two way solenoid so i can up the boost at the flick of a switch, and if so where would be the best place to plumb it in? Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 30, 2006 Share Posted October 30, 2006 Have you got a restrictor ring? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 30, 2006 Author Share Posted October 30, 2006 Have you got a restrictor ring? Yep! Quote Link to comment Share on other sites More sharing options...
osso Posted October 30, 2006 Share Posted October 30, 2006 you know, the reason why you were only getting 0.8 bar, is because they reconnected the vacuum hoses at the back of the second turbo the wrong way round, when you had the turbo replaced. Quote Link to comment Share on other sites More sharing options...
Ric Posted October 30, 2006 Share Posted October 30, 2006 i did that, pain the arse, well one of the VSVS i put the vacume hose on the wrong way round Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 30, 2006 Author Share Posted October 30, 2006 you know, the reason why you were only getting 0.8 bar, is because they reconnected the vacume hoses at the back of the second turbo the wrong way round, when you had the turbo replaced. No, i changed the turbos and all connections are exactly as they should be, been through the lot:( Quote Link to comment Share on other sites More sharing options...
osso Posted October 30, 2006 Share Posted October 30, 2006 Just a thought, I dont think you've ever got around to sorting out your boost problems, to be honest i think you should ditch the sequential system and go single Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 30, 2006 Share Posted October 30, 2006 so i ended up taking everything out of the equation, and ended up running off just the two waste gates, What exactly do you mean by this? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 30, 2006 Author Share Posted October 30, 2006 Just a thought, I dont think you've ever got around to sorting out your boost problems, to be honest i think you should ditch the sequential system and go single Yeah me to:) just have to wait until i have the spare cash, so i will have to sort something for the interim, short of riping the whole lot out and going through it yet again, i'm at a loss bet its something really simple, i do have a tendency to overlook the obvious:blink: Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 30, 2006 Author Share Posted October 30, 2006 What exactly do you mean by this? The waste gates on each turbo, no VSVs or other actuators, the relevant actuators for TTC mode are wired open. Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 30, 2006 Share Posted October 30, 2006 The waste gates on each turbo, no VSVs or other actuators, the relevant actuators for TTC mode are wired open. There is only one wastegate, if you're talking about the EGBV then this doesn't open at all in TTC. Do you mean you mechanically wired the IACV and EGCV actuators open? Did you block off the boost feed to the pressure tank? If the car boosted properly in this setup then the problem must lie in the control of the opening of turbo 2 and you should be able to work back to isolate the fault. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 30, 2006 Author Share Posted October 30, 2006 There is only one wastegate, if you're talking about the EGBV then this doesn't open at all in TTC. Do you mean you mechanically wired the IACV and EGCV actuators open? Did you block off the boost feed to the pressure tank? If the car boosted properly in this setup then the problem must lie in the control of the opening of turbo 2 and you should be able to work back to isolate the fault. Yes only one acts as a waste gate when in sequential mode, but in TTC mode they both are waste gates, yes i wired both the IAC and the EGCV actuators open, whats the reason for blocking the feed to the pressure tank? as it makes no odds if both actuators are wired, and unfortunately it didn't boost to more than .8 bar so i went through each remaining VSV in turn and bypassed them, and it wasn't until i bypassed the waste gate VSV that i got 1.2 bar. Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 Yes only one acts as a waste gate when in sequential mode, but in TTC mode they both are waste gates They don't The EGBV on turbo 2 is situated *after* the turbo. It joins the output of the turbo to the downpipe of #1, so that when it opens it allows exhaust gas to flow *through* turbo#2, thus spinning it up, and then out the exhaust pipe, bypassing the still-shut EGCV. If it really acted as a wastegate, it'd bypass the flow of gas around turbo #2, which doesn't really help it spin up Opening it when both turbos are running will have no effect. -Ian Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 31, 2006 Author Share Posted October 31, 2006 Maybe i'm getting this wrong but i don't think so, both turbos have a waste gate in the exhaust housing like any normal turbo, unless i didn't look closely enough when i had mine apart! ( have you got a pic of the exhaust housing of both turbos?)controlled but actuators, correct, the only difference is that they are controlled differently by the VSVs which open or close in order to activate the wast gates to achieve either pre spool of boost control depending on it being turbo one or two. Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 31, 2006 Share Posted October 31, 2006 Maybe i'm getting this wrong but i don't think so, both turbos have a waste gate in the exhaust housing like any normal turbo, As Ian said (who knows far more than me btw), the valve that you're calling a wastegate on turbo 2 is after the turbo. The exhaust gases still have to go through the turbo, whereas the actual wastegate on turbo one is before the turbo to bleed off exhaust gas before it can spin the turbo up further. Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 I've doodled on a piccy of the setup to demonstrate how it works. The red lines are the path the exhaust takes through the wastegate and the EGBV. You can see that the EGBV allows exhaust gas to flow even with the EGCV shut, but it doesn't at any point allow exhaust gas to go around turbo#2, only through it. If anything, having it open when the EGCV is open as well would cause turbulence and increase exhaust backpressure a weeny bit. -Ian Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 31, 2006 Author Share Posted October 31, 2006 As Ian said (who knows far more than me btw), the valve that you're calling a wastegate on turbo 2 is after the turbo. The exhaust gases still have to go through the turbo, whereas the actual wastegate on turbo one is before the turbo to bleed off exhaust gas before it can spin the turbo up further. Sorry no its not i have just had a look at the exhaust housing of both turbos and they both have identical internal waste gates, i think there is some confusion over just what is being called a waste gate here, i'll take some pics and post them. Edit, i beg both your pardons, if i hadn't been i such a hurry to be right i would have pulled out no1 and no2 exhaust housings out the draw instead of two no 1:stupid: that I'll teach me to pay attention:innocent: one slice of humble pie eaten;) So Steve and Ian i now see where your coming from and its starting to make sense, so if i have a look and a good think about it i should be able to track down just why the boost is behaving the way it is, and if either of you have any more ideas, i will be happy to listen:) Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 The turbos do indeed look similar, but there is one important internal difference. The second turbo has a deeper exit from the impeller wheel because it houses the apeture leading to the egbv. So *all* the exhaust gas goes through the turbo before it reaches the valve. In turbo #1, the apeture for the wastegate valve is before the impeller, so the gas has the option of bypassing the turbo and avoiding contributing to boost - just like a wastegate. #2 just can't do this, all the boost goes through the turbo before it can reach the valve. The chunk of cast iron that they both plumb into is also differently plumbed for each turbo. See attached pics These are old resource images I took ages ago, you can't actually see the EGBV input hole because of the angle, but it's down there and up a bit, sort of where the red arrow is pointing -Ian EDIT - you amended your post while I was putting all this together I guess you see what I mean now lol Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 As to why you aren't getting the required boost, as the wastegate is marginal already so it can't be that which is limiting it to 0.8bar, when it's fully open you'll be lucky to keep it below 1.5bar without a restrictor, and I doubt you accidently fitted a 0.8bar ring. The only way of limiting it beyond the wastegate is via a restrictor ring or some other exhaust obstruction so I'd say look around the EGCV, if it's not opening fuly you'll get a massive restriction in the exhaust, causing boost to be limited. Can't really think of any other way it could be lowered. -Ian Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 31, 2006 Author Share Posted October 31, 2006 I think what i can't get my head around is that after going through everything and not finding a fault, bypassing everything except the no1 waste gate and the exhaust bypass valve;) gave me 1.2 bar, but just reconnecting the no 1 waste gate actuator VSV has limited it back to .8 bar, its starting to look to me like its all down to the restrictor ring, but i have measured it (just can't remember the dimension) and it seems to be the same size as most other people have, but even so i think my only recourse it to take it out and give it a try (carefully;) ) Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 I think what i can't get my head around is that after going through everything and not finding a fault, bypassing everything except the no1 waste gate and the exhaust bypass valve;) gave me 1.2 bar, but just reconnecting the no 1 waste gate actuator VSV has limited it back to .8 bar, Actually, if the EGCV isn't opening properly, that could make sense. As we've already ascertained, the function of the EGBV is to let exhaust pass through #2 when the EGCV is still shut. So if you wire that open when the EGCV isn't working correctly, you'll allow #2 to produce more boost by opening up an extra path for the gas to flow. -Ian Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 31, 2006 Share Posted October 31, 2006 the function of the EGBV is to let exhaust pass through #2 when the EGCV is still shut. So if you wire that open when the EGCV isn't working correctly, you'll allow #2 to produce more boost by opening up an extra path for the gas to flow. I was under the impression from tricky-rickys first post though, that the IACV and EGCV actuators were mechanically wired open at the time. Would that not make the state of the EGBV irrelevant? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 31, 2006 Author Share Posted October 31, 2006 Yep there wired open and i did check the EGCV to make sure that it wasn't broken, and opened before i wired it. Quote Link to comment Share on other sites More sharing options...
Steviekid Posted October 31, 2006 Share Posted October 31, 2006 Just to clarify, when you got 1.2bar the IACV and EGCVs were mechanically wired open and the EGBV VSV was bypassed. You also had the boost feed pipe still connected to the wastegate actuator and the other pipe from the actuator (that originally went to the wastegate VSV) blocked off. Is this correct? Then all you did was put the wastegate VSV back in the equation and you dropped to 0.8bar? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 31, 2006 Author Share Posted October 31, 2006 Just to clarify, when you got 1.2bar the IACV and EGCVs were mechanically wired open, Yes and the EGBV VSV was bypassed. Yes. You also had the boost feed pipe still connected to the wastegate actuator, Yes. and the other pipe from the actuator (that originally went to the wastegate VSV) blocked off. Is this correct? No not quite! the other boost pipe is conected to the EBV actuator, and its original connection to the pressure side of the tubo pipe via the pressure tank (one way valve side) was retained as std, so a complete loop, Then all you did was put the wastegate VSV back in the equation and you dropped to 0.8bar? Yes. aa Quote Link to comment Share on other sites More sharing options...
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