richardharmon Posted February 20, 2004 Share Posted February 20, 2004 Right, I am having a problem with the sequential set-up, sometimes when I kick down no2 turbo doesn’t bother coming on line. I have made a quick visual inspection of all the hoses and they seem intact, though some are difficult to inspect and require further attention. Out of curiosity I wanted to measure the pressure in the pressure tank to see if the one-way valve was functioning. To perform this test I teed off the input pipe that goes to the air intake control valve's VSV (the one on the top of the engine) and connected a boost gauge. I went for a drive and observed the pressure readings. As you would imagine, when on boost the pressure rises quickly in line with the turbo boos pressure. When I take my foot off the throttle however the pressure very quickly drops back to 0.5 bar. I continued to drive off boost and the pressure gradually crept back down to about 0.2 bar. After idling the car for a few minutes the pressure dropped further to about 0.1 bar. Has anyone ever performed this sort of test before or know what the expected results are? I would love to know why no2 just doesn’t bother sometimes and you can guarantee it’s just as you’ve pulled out to overtake! Any more ideas? Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 20, 2004 Share Posted February 20, 2004 Let me guess. The 2nd turbo won't come online for the first time you stick your foot down, but is fine after that... The same fault happens again, if you take it easy for about 5 minutes... Also, if you stop the engine and re-start, the 2nd turbo won't come in again in first gear, but is fine afterwards... Until you start to take it easy again... Or, you can stick your foot down to overtake, the 2nd turbo doesn't come on line, remove your foot, then floor it again, and the 2nd comes in! How close am I so far??? Link to comment Share on other sites More sharing options...
dude Posted February 20, 2004 Share Posted February 20, 2004 More and more now seem to suffering this problem , mine drove me mad and between the tech heads on the bbs we must have tried everything , good luck hunting but your savior could well be ETTC!!!! Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 20, 2004 Share Posted February 20, 2004 ETTC was the solution that works best for me! - In fact, I much prefer it. Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 20, 2004 Share Posted February 20, 2004 Originally posted by richardharmon Right, I am having a problem with the sequential set-up, sometimes when I kick down no2 turbo doesn’t bother coming on line. I have made a quick visual inspection of all the hoses and they seem intact, though some are difficult to inspect and require further attention. Out of curiosity I wanted to measure the pressure in the pressure tank to see if the one-way valve was functioning. To perform this test I teed off the input pipe that goes to the air intake control valve's VSV (the one on the top of the engine) and connected a boost gauge. I went for a drive and observed the pressure readings. As you would imagine, when on boost the pressure rises quickly in line with the turbo boos pressure. When I take my foot off the throttle however the pressure very quickly drops back to 0.5 bar. I continued to drive off boost and the pressure gradually crept back down to about 0.2 bar. After idling the car for a few minutes the pressure dropped further to about 0.1 bar. Has anyone ever performed this sort of test before or know what the expected results are? I would love to know why no2 just doesn’t bother sometimes and you can guarantee it’s just as you’ve pulled out to overtake! Any more ideas? OK, this sounds the sort of thing i see regularly with the twin sequential turbo Mazda Rx-7 disaster. The Mazda set up is utterly notorious for playing silly buggers and often only a dedicated and totally thorough check through the myriad of slenoids, hosing, one way valves and birds nest wiring will sort it. From bitter experience i can predict with some certainty just where a fault may lie with those. I'd like to say the same with the better and simpler MKIV TT set up, but as it is usually so damned reliable i haven't had many cars where an owner was happy to have such an intermittent problem resolved, no matter how long resolving it took. "Billy" off here has an intermittent boost problem, but sods law said it never missed a beat whilst I had it in for suspension work... I am very happy to diagnose and fix this, but i will say now, it is impossible to do this for a fixed price. it might take minutes, it might take days. The bits could be none, just labour, or very expensive. I would like to have a look at similar or your car, but it's your call Link to comment Share on other sites More sharing options...
Homer Posted February 20, 2004 Share Posted February 20, 2004 This is exactly the same problem with my car - I cannot get boost after sitting in traffic or being off boost for a while.... exactly like Matt said. Will be going TTC once the CW de-cats have arrived Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 20, 2004 Share Posted February 20, 2004 I now know of at least 6 Supra's with this problem, but with the TTC mod, IMO it's easily tolerable. Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 21, 2004 Share Posted February 21, 2004 Originally posted by Loid This is exactly the same problem with my car - I cannot get boost after sitting in traffic or being off boost for a while.... exactly like Matt said. Will be going TTC once the CW de-cats have arrived Seems odd to buy a car Toyota ploughed a fortune into to give it sequential turbos for superb low AND high end power, only to bodge it into a parallel turbo engine! If you could fix the problem for a sensible fee would you rather stay with the original sequential operation? Link to comment Share on other sites More sharing options...
Dragonball Posted February 21, 2004 Share Posted February 21, 2004 Agreed Chris I dont like TTC - never did - just a personal thing mind you! As a matter of interest is there any common ground with the six that you know of? Boost controller? Dump valve? Could this be caused by a loss of pressure from faulty dump valves for instance? Or is that too simple? Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 21, 2004 Share Posted February 21, 2004 A boost leak at part throttle would have to be BIG, but it is just about conceivable, I think. I would suspect problems elsewhere though. If i get a bit quieter in the next few weeks I'd be interested to have a go at one of these. no fix, no fee, but I'd need for a few days i suspect. I'd like to offer an answer to be honest... Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 21, 2004 Share Posted February 21, 2004 Originally posted by Chris Wilson Seems odd to buy a car Toyota ploughed a fortune into to give it sequential turbos for superb low AND high end power, only to bodge it into a parallel turbo engine! If you could fix the problem for a sensible fee would you rather stay with the original sequential operation? I can see what your saying, the sequential system is a nice idea, but IMO, it was designed to make the car more drivable for those that didn't want out and out performance... So that someones wife could drive it to the shop at the weekend for example. In TTC mode, the car acts more like a 'normal' turbo'd car, with progressive boost build up, leading to full boost around 3,500 rmp as opposed to a big kick up the backside at 4,000 rpm. I can see why people like the sequential system, especially on the auto's. As I've always said, TTC is a personal preference. Chris, If you were more local to me, I'd love you to have a look, if for no other reason to know what the problem is. I'm fairly sure I do have a boost leak issue that I haven't managed to find yet, but I don't think this is common to all the car's I know of. Some of which are stock, some are modified, no common ground that I can say... I'm also fairly sure it's going to be something fairly simple, but it needs someone like Chris to trace it, and someone that's prepared to take the gamble on a big or small bill at the end of the job. So far, I've checked most of the hoses, I've changed the 3 VSV's at the rear end of the engine for known good ones, I've tried plumbing in the boost controller to use the front VSV, then to bypass it, and with no boost controller at all. If it sheds any more light, even in TTC mode, when the car is first started, I have to take the revs to over 4k, before it locks in twin mode. On it's first WOT, the second turbo doesn't kick in... Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 21, 2004 Share Posted February 21, 2004 Matt, and anyone else with the same problem: Do your cars have a none stock BOV? None stock air box? Let's see if we have any common ground we can find. In fact, if it's not too much of a PITA, list *ALL* engine mods please. Link to comment Share on other sites More sharing options...
dude Posted February 21, 2004 Share Posted February 21, 2004 If its any help i also checked all the vsv's the pressure tank etc and came to the conclusion that it is either a fed from the ECU or a signal the ECU is not getting that is the cause (tried an ECU as well) , when i activated the vsv's manually with an earth via a switch in the car i could get 2nd online at 4000rpm everytime !!! Dude:flame Dev Link to comment Share on other sites More sharing options...
dude Posted February 21, 2004 Share Posted February 21, 2004 Mines ECU * HKS BOV * Blitz SBC-ID * De-CAT HKS filter uprated pump and FSE 550 inj SAF-C * changed these for other known good items . Dude :flame Dev Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 21, 2004 Share Posted February 21, 2004 Originally posted by Chris Wilson Matt, and anyone else with the same problem: Do your cars have a none stock BOV? None stock air box? Let's see if we have any common ground we can find. In fact, if it's not too much of a PITA, list *ALL* engine mods please. When I first got this car, the fault was already there. At that time it had an Apexi indusction kit, but I changed that back to a stock airbox with TRD panel filter... That made no difference. I've got a HKS SSQV BOV, but I have also tried the stock one, that made no difference either. Mod list, Stock airbox with TRD panel filter (changed - No difference) TRL VFCC Blitz DSBC (removed/bypassed - No difference) Apexi S-AFC2 (Installed by me, no difference before or after) Apexi ITC (Installed by me, no difference before or after) Blitz Nur-spec R + decatted (not changed, but I can't see it woud have any effect) HKS R-type intercooler (fitted by me, no difference before or after) Walbro high pressure fuel pump (fitted by me, no difference before or after) FSE fuel pressure regulator (I know you don't like them but it was fitted by me, no difference before or after) HKS SSQV blow off valve (changed for a stock one, and made no difference) ERL Aquamist water injection (now removed, made no difference) Just to add to my previous chain of events; At the times when the 2nd won't engage, no.1 only boosts to about 0.3 bar. It will hold 0.3 bar all the time you are at WOT, right up to 6500rpm. As soon as I change gear, no.1 goes up to about 0.7, then no2 comes in as it should. In sequential mode, if you gently accelerate through the 4k mark, no.2 will come online correctly. Not much help, I'm sure... Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 21, 2004 Share Posted February 21, 2004 Matt, thanks for that, interesting stuff, all info welcome, I intend to crack this... Link to comment Share on other sites More sharing options...
Nic Posted February 21, 2004 Share Posted February 21, 2004 I had what sounds to be a similar problem a few months ago, where every now and again (not all the time) I'd accelarate and it felt as though one of the turbos wasn't coming on line (mine is set in TTC.) The fault turned out to be the electronic part that opens the valve for the 2nd turbo, is this the vsv:stupid: which was functioning intemittently It was replaced and the problem was cured. Link to comment Share on other sites More sharing options...
richardharmon Posted February 21, 2004 Author Share Posted February 21, 2004 Originally posted by Matt Harwood Just to add to my previous chain of events; At the times when the 2nd won't engage, no.1 only boosts to about 0.3 bar. It will hold 0.3 bar all the time you are at WOT, right up to 6500rpm. As soon as I change gear, no.1 goes up to about 0.7, then no2 comes in as it should. In sequential mode, if you gently accelerate through the 4k mark, no.2 will come online correctly. I get this, *exactly* as Matt describes it. Mods: Blitz NurSpec-R, full de-cat (Blitz mid-pipe and CW down-pipe), RLTC, that’s about it! I will do some further testing, maybe: Connect some sort of electrical indicator to the VSV valves and check the correct signal is getting to them. Try putting a one-way valve in the line that supplies the pressure tank, to see if holding more pressure in there makes any difference. Shout up if you think this one is a bad idea for any reason. Link to comment Share on other sites More sharing options...
Ian C Posted February 21, 2004 Share Posted February 21, 2004 With ignition off, try attaching a spare pipe to the bit ringed in red: http://www.ian.chisholm.clara.net/pix/pipe.jpg and blow down it. You shouldn't be able to. If you can, you may have sussed your problem... Let me know. -Ian Link to comment Share on other sites More sharing options...
Steve Cargill Posted February 21, 2004 Share Posted February 21, 2004 When this problem happens, do you get any unusual noises at all? Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 21, 2004 Share Posted February 21, 2004 Originally posted by Steve Cargill When this problem happens, do you get any unusual noises at all? Yep. Blaring of horns, cries of "shit, that was close" from the passenger seat, "phweww" noises from the driver.... Link to comment Share on other sites More sharing options...
dude Posted February 21, 2004 Share Posted February 21, 2004 Originally posted by Chris Wilson Yep. Blaring of horns, cries of "shit, that was close" from the passenger seat, "phweww" noises from the driver.... creaking of leather as the cheeks pucker up due to the oncoming artic !!!!! Dude:flame Dev Link to comment Share on other sites More sharing options...
Steve Cargill Posted February 22, 2004 Share Posted February 22, 2004 Originally posted by Chris Wilson Yep. Blaring of horns, cries of "shit, that was close" from the passenger seat, "phweww" noises from the driver.... Originally posted by dude creaking of leather as the cheeks pucker up due to the oncoming artic !!!!! Dude:flame Dev LOL, PMSL - just what I needed to break into a smile this morning. Currently have a monster hangover and it hurt too much when I laughed Link to comment Share on other sites More sharing options...
richardharmon Posted February 22, 2004 Author Share Posted February 22, 2004 I tried blowing down the pip ein the picture, couldn't. Was hoping that was it! Is that the line that goes to the pressure tank input then? Link to comment Share on other sites More sharing options...
Matt Harwood Posted February 23, 2004 Share Posted February 23, 2004 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... Link to comment Share on other sites More sharing options...
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