2jzgte losing boost

[the fallen303]

hey guys, got issues with my 2jzgte jzs147 aristo. for some reason, pulling through the revband, as it changes from single turbo to twin, you'll get a surge of power for a second when the second turbo comes online, then car will lose all boost pressure.

if you feather the throttle to keep boost pressure under when the wastegate should limit boost to (say 7 or 8psi or whatever it's supposed to be, so sit at 5-6), and select what gear car is in so doesn't change up, it will pull right through and hold boost to redline, but as soon as go over when the wastegate should limit the boost to, it drops all boost, and can't get it back until you back off and let it drop back to single turbo mode.

any thoughts of where i could start looking to try and diagnose this problem? i've been looking everywhere for a leak, but can't find one.

john

[escortman]

Probably something to do with all the stupid sequential vsvs and vacum cannister thing under inlet manifold might be leaking, you ll have more luck checking overseas supra forums i found some even had like a checklist to identify what was causing it.

[the fallen303]

sweet thanks will do.

[BlakeNZ]

put a 1JZ in it! ha ha ha.
text me, as i lost my phone with your number in it.

[the fallen303]

hahahaha, nice blake, but thats what the supra's for the aristo can slum it with the 2j :p will flick ya a txt

[Girvs]

Single turbo will fix that Johnny....

[Luke - BZG]

Yup, ditch the twins

Get a gt35/40

[the fallen303]

again thats what the supra's for, aristo is just getting bpu's, so the twins stay, unless they die, and even then, i have a spare set to take their place.

trust me if i had the money i'd love to go nuts on it, but yeah, it's supposed to be the tame daily, haha, which i think the twins do a better job of.

[Luke - BZG]

Ok... Well, in that case I'd look at the wastegate actuator, sounds like its opening fully and staying open instead of varying amounts.

The wastegate on the front turbo is the only actual wastegate, so look at that first. The wastegate on the rear turbo must be used for the sequential system, reading from: http://mkiv.supras.org.nz/techo.htm#BOOST_BASICS

[the fallen303]

yeah the sequential system has some bad voodoo magic in it. but yeah, front wastegate controls boost, rear is just for controlling flow for the sequential or some bullshit.

when i did the boost controller, the front wastegate actuator is dual port, i tapped into "apparently" the right one for basic boost control. however when i removed the boost controller, i left the tee in the line and blocked off the other end, as getting in there is a major pita (aristo runs viscous fan, not normal like mk4 2j).

wondering if maybe one of the pipes might have a split, as they're all connected :/ will try and get back in there and replace the piping

boost controller is an hks evc-4, which does support dual port actuation. might look into replacing tubing to make sure is ok, the will plumb up controller as dual port