Ian C Posted February 23, 2004 Share Posted February 23, 2004 That hose is the feed to the pressure tank and exhaust gas bypass valve. It's where I found a leak on mine, on the pipe from the valve actuator to the VSV of the EGBV and it hadn't been affecting the sequential system except occasionally it wouldn't engage turbo 2... Especially if I booted it... Sound familiar? Y'see, the hose was split yet the outer rubber skin was strangely stretched, which says to me that over time the split had been mostly shut but sometimes yawning open - say on sudden high boost. When it opened it would have dumped all the pressure in the EGBV system meaning the second turbo wouldn't spin up before it was brought onstream, so it would all go wrong - low boost pressure as the intake side fought against the turbine side. Anyway - not being able to blow through it is a good thing. I'll have a look at the pressure map and knock up as many tests as I can work out if you want. -Ian Edited so it's actually correct, doh. Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Originally posted by Matt Harwood The blow-job thing didn't work for me either... Incidentally, I have no idea if this is related or not but... I've tried doing Ian C's first turbo boost mod, and it made absolutly no difference to my 1st turbo at all. Regardless of the position of the bleed valve, fully open or fully closed, made no difference... What does your 1st turbo boost to then? Have you got a photo of your install? I'll have a think about this one, it's a good sign of something not working... -Ian Link to comment Share on other sites More sharing options...
richardharmon Posted February 23, 2004 Author Share Posted February 23, 2004 Originally posted by Ian C That hose is the return from the wastegate and exhaust gas bypass valves. It's where I found a leak on mine, on the pipe from the valve actuator to the VSV of the EGBV and it hadn't been affecting the sequential system except occasionally it wouldn't engage turbo 2... Especially if I booted it... Sound familiar? Y'see, the hose was split yet the outer rubber skin was strangely stretched, which says to me that over time the split had been mostly shut but sometimes yawning open - say on sudden high boost. When it opened it would have dumped all the pressure in the EGBV system meaning the second turbo wouldn't spin up before it was brought onstream, so it would all go wrong - low boost pressure as the intake side fought against the turbine side. Anyway - not being able to blow through it is a good thing. I'll have a look at the pressure map and knock up as many tests as I can work out if you want. -Ian Thanks Ian - What do you make fo the pressure readings I'm getting from the pressure tank (first post), any thoughts on that? Link to comment Share on other sites More sharing options...
richardharmon Posted February 23, 2004 Author Share Posted February 23, 2004 By the way, does anyone know if this problem can cause any damage? Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 The pressure tank is supposed to be a short term cache for pressurised air as far as I can tell, so that it can work certain actuators after you are off-boost. So the slow deflation sounds normal. You quoted the version where I had it all wrong where that hose goes to Relying on memory while at work and other excuses -Ian Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Originally posted by richardharmon By the way, does anyone know if this problem can cause any damage? Don't keep your foot in on turbo 1 otherwise you'll get massively overheated airflow as it overspeeds to 1bar+ of boost. Apart from that, which is easy to catch as you know when it's all going pete tong, no. -Ian Link to comment Share on other sites More sharing options...
richardharmon Posted February 23, 2004 Author Share Posted February 23, 2004 Thanks, I'll keep on prodding it until I find something. Any other tests you can think of would be much appreciated. Richard. Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 From a theoretical standpoint, based on the symptoms Matt described, I'd say it's got something to do with prespooling the second turbo. If you don't prespool it and it is brought onstream with turbo one going at full chat, the boost pressure from 1 will jam into 2, attempting the path of least resistance, and try to spin it backwards. Now, the exhaust will try and spin it forwards at the same time so pretty much what you'll get is a deadlock situation. I'd imagine that eventually #2 would get up to speed but before it can make a noticeable impact on boost pressure you've changed up. So, this means your boost pressure will mostly vent to atmosphere via turbo 2, leaving, say 0.3 to 0.5bar entering the manifold. If you ease up the rev range and #2 is brought onstream without much positive boost pressure trying to suddenly backspin it the exhaust gas wins almost immediately and #2 spins up and starts contributing to the airflow, so you wouldn't notice anything wrong. If you change up while above 4krpm both turbo's start from an equal footing (onstream, offboost) and so behave normally as well. It would have to be an intermittent problem, such as a flexing hose that only opens up at the highest of #1 boost levels. -Ian Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Try this: http://www.ian.chisholm.clara.net/pix/pipe2.jpg Take the red highlighted hose off the VSV and blow down it. You should hear air coming out in the intake blend pipe (near the BOV). If you can't, that's bad. If you can hear air, take the first pipe that I mentioned in this thread off, cover it with your thumb and blow down the red highlighted pipe again - no air should travel until you remove your thumb. Also, take the yellow highlighted hose off the VSV (after putting the red one back ) and blow down that, you should find a sort of spongy resistance. That's yer pressure tank doing it's business. Incidentally you can test VSVs by taking them off the car and feeding them 12v You'll hear a click and they will let air flow (or stop airflow, depending on the type). Your PC is a great 12v source (yellow wire) -Ian Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 23, 2004 Share Posted February 23, 2004 Just to clarify a few points... When the sequential bit all goes to pot and no.2 won't play, (good techie terms eh?!), no.1 will reach 0.3 bar as usual, and there is no boost fluctuation at all, right up to the gear change, (7000 rpm if you want to), as soon as you change gear, everything is working properly. If I'm following your train of thoughts correctly, I'm fairly sure you'd see something happening to the boost pressure as no.1 and 2 were 'battling'. A drop maybe? But either way, whilst it's in this state, it holds 0.3 steadily right up the rev range. My first turbo normally reaches 0.65 - 0.70ish. I don't have a photo, as I took it all back off after it wouldn't work, but it was done using Richard, (Hardhead42's), diagrams and pictures, using a bleeder and a T piece. I have spoken to Leon about this ages ago, he checked the two hoses you had problems with whilst the gearbox was off, (much easier that way!), they were fine... I agree that the first turbo mod having no effect is probably related to the whole sequential problem in some way. Does that help at all? Link to comment Share on other sites More sharing options...
richardharmon Posted February 23, 2004 Author Share Posted February 23, 2004 Thanks for that Ian. The yellow highlighted hose it the one I used to measure the pressure-tank pressure levels and yes, blowing down that one is spongy. I will give those other tests a try tomorrow in the daylight. It looks like it’s probably going to be either a leaking hose (that I missed visually) or the VSV then, doesn’t sound too bad! Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Well, Matt, boost control on #1 is by that VSV blocking airflow so pressure can build up behind the EGBV actuator. If you bleed some pressure past the VSV then, well, it works like a bleed valve except the air isn't dumped to atmosphere the way we do it. Now, from experience a mere half a turn will give a 0.1bar boost pressure rise due to this bleeding off, so fully opening the valve should give you runaway boost - 1bar or higher. As it isn't, it says to me that it doesn't matter how much pressure gets to the EGBV actuator, it won't change anything. So - blockage in the feed pipe? A leak? I don't know, I'm trying to give you guys some ideas on what to test - theory only gets you so far like, for example, the theory that a big fast sports car gets you laid more. ha. -Ian Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 23, 2004 Share Posted February 23, 2004 Gotta stop meeting my car like this! The tests all performed exactly as you said they would. (unfortunatly). The yellow hose, hissed as I removed it, and the car hasn't been driven since yesterday afternoon, so I guess the pressure tank is working alright. I'm certain it's not a VSV problem, as I've swapped them all over from my auto, and the sequential system on that, worked/works perfectly... Ian, you know more about the sequential operation theory than most people, so, thank you for your input. I'm more than happy to try anything - Not that it really affects me, but I'd just love to know what the problem is... I bet it'll be something simple. By the way, does your other theory work? Link to comment Share on other sites More sharing options...
richardharmon Posted February 23, 2004 Author Share Posted February 23, 2004 That's interesting, my yellow hose didn't even hiss when I took it off, after testing. Looks like your pressure tank holds way better than mine. Does anyone know where the T-junction marked on the attached picture actually lives on the car? Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Originally posted by richardharmon That's interesting, my yellow hose didn't even hiss when I took it off, after testing. Looks like your pressure tank holds way better than mine. Does anyone know where the T-junction marked on the attached picture actually lives on the car? It's in that morass of metal pipes that goes across the top of the turbos. Trace back from the one I originally said to blow down and you'll find it tees off near the back of the engine bay. Quick, while I've got your attention Matt, is it normal to have no resistance between the battery positive and chassis ground (with the negative terminal disconnected)?!? Is it just permanently live wired things like the stereo giving that path from +ve to -ve? Or do I have a monster short somewhere? -Ian Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 23, 2004 Share Posted February 23, 2004 I suspect EGBV problems myself. Either the actuator is faulty or the flap valve itself is seizing. Just a gut feeling... If anyone has a Mityvac they could test this, or even a pressure gauge (old boost gauge) plumbed as a T into the EGBV feed line would be interesting. Link to comment Share on other sites More sharing options...
TLicense Posted February 23, 2004 Share Posted February 23, 2004 I'm not sure but I may be seeing something similar or maybe related or maybe not at all. Over the past couple of days, when flooring it from around 3000 rpm in a reasonable gear (4th/5th) no.2 is intermittantly not coming on line as expected, then by about 5000 rpm, BANG, all at once. Happened again this evening. Accelerating towards a bend, no2 is online everything sweet. Brake and turn in, accelerate hard out of the corner and it no no2 untill 5000 rpm then all at once. My mods are listed in my sig. I'm currently driving at 18 psi. (Well not whilst typing this ) Regards Link to comment Share on other sites More sharing options...
Ian C Posted February 23, 2004 Share Posted February 23, 2004 Originally posted by Chris Wilson I suspect EGBV problems myself. Either the actuator is faulty or the flap valve itself is seizing. Just a gut feeling... If anyone has a Mityvac they could test this, or even a pressure gauge (old boost gauge) plumbed as a T into the EGBV feed line would be interesting. So the most and least technical, as voted by you lot, agree on the problem area Never thought to check actual operation See if it's sticking and wire up a boost gauge to see what pressure the actuator gets is a grand idea. -Ian Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 23, 2004 Share Posted February 23, 2004 I have now repaired 3 or 4 of these assemblies where the arm has come unwelded from the shaft. It may have been a poor weld, or it MAY have been due to excess leverage `cos the flap valve was sticking shut! There is an adjustable stop scew on the arm, to limit how far shut the valve can get. I don't recommend anyone playing with this unless you reference EXACTLY where the screw is before you twiddle it, so you can return to the original datum, but I assume the screw is there to stop the butterfly biting into the casting and "sticking". It's the area I would look at should i have a car in that reliably played up, if that doesn't sound too Irish? Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 24, 2004 Share Posted February 24, 2004 Bugger! - I had all that it bits a few months back, and I didn't think to check it's operation... Ian, I've never actually checked for resistance with a negative removed from the battery, but there will be all sorts of things that will be causing ground loops. Anything with memory, anything wired permanantly live etc. The interior light would also do this if you were checking whilst a door was open... Are you still having problems with your electrics? - What? Edited to say, don't worry about answering Ian, I've found your thread. Link to comment Share on other sites More sharing options...
anthonyj Posted February 25, 2004 Share Posted February 25, 2004 Interesting - I have something similar but now I don't think it is the same problem... Mine is an automatic and the only time I notice it is when the box kicks down and boots the revs close to 6k rpm (i.e. when it shouldn't really have bothered kicking down). However, I do get full boost off no1 (.8 bar) and if I keep it nailed then after, say, 5 seconds, no2 suddenly spools up (note that it doesn't kick in anything like as fast as it does at 4k rpm - it takes a good couple of seconds to reach full boost). I also think it is worse when the weather is warmer (i.e. I've not seen it at all recently in the cold weather we've been having). From the sounds of it, this is subtly different to what you guys are experiencing? In any case, it certainly isn't getting any worse and doesn't do it very often so I'm disinclined to fiddle about with stuff too much in case I make it worse!! Just out of interest - why did Toyota make the 2nd turbo come online at 4k rpm? It seems too high to me - the 1st turbo is spun up well before then and it would be nice to get the grunt from a bit lower (I guess you guys with manuals wouldn't notice it as much). Is there a reason why and is it possible to move the point at which it happens?! Link to comment Share on other sites More sharing options...
TLicense Posted February 25, 2004 Share Posted February 25, 2004 Anthony, That is exactly the problem I've got. I'm just on my way outside to sort this out. One way or another. I'll let you know how I get on. Regards Link to comment Share on other sites More sharing options...
TLicense Posted February 25, 2004 Share Posted February 25, 2004 OK, I've just been out and given all the hoses Ian mentioned a blow down with the ignition off as directed. Unfortunately it all worked as it should. However I did notice that pretty much all of the hoses were very brittle. I'm kinda guessing there may be a problem there. I'm going to get some replacement hoses from work tomorrow and change them all and will let you know how I get on. Oh yeah I'm also thinking about adjusting the valves operating engine speeds using the AEM so that it would effectively be a TTC, or reduced RPM. Can anybody think of the best way to test all these? I should be able to log the outputs from the AEM shouldn't I? Hopefully that way I can see if its an electrical problem at all. Regards Link to comment Share on other sites More sharing options...
TLicense Posted February 25, 2004 Share Posted February 25, 2004 Well I think I've managed to fix this. For me at least. I managed to find some tubing left over from when I installed the SSQV, and replaced as much hose, as I had spare. I replaced all of the hoses Ian said to check, and gave the VSV plugs a good push in to make sure none ha worked loose. I've just taken her for a spin and WOAH BABY. Worked prefectly every time. In fact I've had to turn down the boost on the SBC! What was boosting to a perfect 18 psi every time went 18.7. Anyway, tomorrow I'll replace all of the hoses across the top of the engine. I know CW does not recommend silicon hoses, so which ones should I ask for. Mind the guy in the stores should be able to sort me. Regards Link to comment Share on other sites More sharing options...
Guest Usmann A Posted February 25, 2004 Share Posted February 25, 2004 Just discovered, my dads car is suffereing from the same symptoms. I took the inlet off lately, and it has been ok for a few drives, but tonight, I noticed it was sounding very different, and it turns out that no.2 is not coming online at 4000rpm, its more like 6000rpm, if anything just before 7000rpm. I checked all vac hoses off inlet, and all seems fine, just havent had a chance to check pressure tank as its too hot atm. But if a hose was off from the tank, surely it wouldnt boost at all. Maybe its a loose? All hoses seem to be in good nick, and the visible VSV's are practially intact, and piped up, but the other I ovbiously cannot get through to the other buggers until I strip it down. Any more help Fellas? Thanks Link to comment Share on other sites More sharing options...
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