kaahari Posted August 30, 2008 Share Posted August 30, 2008 Hi! I have now read almost *all* threads with 2.nd turbo broblems. Just few questions! Broblem is that 2.nd turbo wont come online, 1.st boost quite good 0.7-0.8 (2.nd decat) until about 3800-4000rpm, then boost starts slowly go down to about 0.3 at ~5000rpm. Although i have read a lot of threads conserning this broblem, i am not sure is it IACV or EGCV related. Can you suggest where to start looking?? I also took a testdrive with iacv plug off, no change... btw the vsv works! Quote Link to comment Share on other sites More sharing options...
Supradoopa Posted August 30, 2008 Share Posted August 30, 2008 Had the same kind of problem mate. On mine the EGCV actuator arm was sticking, so I got a new one, put that on and after that it worked fine. Quote Link to comment Share on other sites More sharing options...
kaahari Posted August 30, 2008 Author Share Posted August 30, 2008 Ok, thanks! Is there a way to test actuator without taking it off? Quite small space there... Quote Link to comment Share on other sites More sharing options...
Supradoopa Posted August 30, 2008 Share Posted August 30, 2008 The only reason i knew mine was sticking was because everytime i went over the 4k limit she sounded like a tractor and lost quite a lot of power, once I popped the hood I looked down to see it resting in the wrong position. Not sure if there is a good way for testing it without having to take it off via the exhaust. Quote Link to comment Share on other sites More sharing options...
kaahari Posted August 30, 2008 Author Share Posted August 30, 2008 I now (gently) tried to move the actuator "rod", it moves and got a backpressure...but i can hear air moving out from somewhere when moving it, i think from vsv or actuator itself, is it normal? (is the air flowing out via vsv?) Quote Link to comment Share on other sites More sharing options...
kaahari Posted August 31, 2008 Author Share Posted August 31, 2008 (edited) Found cause of broblem. I first checked both vsv and "manually" actuators... both seemed fine. Then followed weird extra pipe to pressure tank and found that two pressure tank pipes were taken off and blocked! So no pressure to actuators! Now two new pipes in place, they were quite easy to change from enginebay without actually seeing them. Could be easier from below? Went to test drive, with new pipes in place car boosting fine after 4000 Car had also hks boost controller, piping was hmm quite "weird"... it is now right. Edited August 31, 2008 by kaahari (see edit history) Quote Link to comment Share on other sites More sharing options...
Supradoopa Posted August 31, 2008 Share Posted August 31, 2008 Wonder why they were blocked off Quote Link to comment Share on other sites More sharing options...
kaahari Posted August 31, 2008 Author Share Posted August 31, 2008 (edited) Wonder why they were blocked off I wonder same! :blink: There was one extra definetly non stock pipe leading to pressure tank. It was connected to HKS boost controller wastegate line and then other end was in pressure tank upper connector. Lower was empty. Maby car was in ttc mode earlier? edit: one question!: I just wonder, why all the guides tell to block wastegate actuator lower hose + wastegate VSV pipe? What exactly wastegate VSV does in stock Supra? Ian C marvellous faq (http://www.mkivsupra.net/vbb/showthread.php?t=35926) dont cover it! Edited August 31, 2008 by kaahari (see edit history) Quote Link to comment Share on other sites More sharing options...
kaahari Posted October 31, 2008 Author Share Posted October 31, 2008 (edited) Hi! How much is the (bar/psi) pressure which controls egcv and egbv actuators? Car is resting for winter, could check these because here have been few 1.st turbo failures in jdm cars, probably due leaking/stuck actuators... Edited October 31, 2008 by kaahari (see edit history) Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 1, 2008 Share Posted November 1, 2008 edit: one question!: I just wonder, why all the guides tell to block wastegate actuator lower hose + wastegate VSV pipe? What exactly wastegate VSV does in stock Supra? Ian C marvellous faq (http://www.mkivsupra.net/vbb/showthread.php?t=35926) dont cover it! Normally there is an open loop of piping that goes from the pressurised side of the turbo to the actuator to the VSV and back to the non-pressurised side of the turbo. This means no pressure on the actuator diaphragm. When the VSV closed, pressure can't escape to the non-pressurised side of the turbo system, so it builds up behind the wastegate actuator and pushes it open. By pulsing the wastegate VSV the boost pressure can be accurately controlled, much like an aftermarket boost controller. The aftermarket boost controller doesn't make use of this return path to the non-pressurised side of the turbos. Instead, its valve blocks pressure from reaching the wastegate actuator, and any pressure in the pipe between the valve and the actuator is vented to atmosphere. When the boost controller valve opens, it stops the pipe to the actuator from being open to atmosphere and instead exposes it to the pressurised air from the turbo, thus pushing the actuator open. Again, this valve can be pulsed to accurately control the boost pressure levels. With this setup, the lower hose on the actuator has to be blocked off to remove the stock wastegate VSV from the loop. Otherwise, when the aftermarket solenoid opens up to expose the actuator to boost pressure, it could just be vented straight back to the non-pressurised side of the turbo because the stock wastegate VSV is open. Either that or the stock wastegate VSV is being pulsed by the ECU to try and control boost and it will interfere with what the aftermarket valve is trying to do. Hope that makes sense, I notice English isn't your first language so I've tried to be as clear as I can -Ian Quote Link to comment Share on other sites More sharing options...
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