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Thread: USDM twin swap wont boost
10-13-2012, 08:30 PM #1
USDM twin swap wont boost
I recently acquired some USDM twins that have very minimal shaft play. My old JDM twins where blowing oil, but boosted fine. Upon swapping over to the USDM twins, I have been unable to make any boost, unlike all the threads I searched that are achieving only 5 PSI, I am getting nothing... As far as I can see, all vacuum hoses are hooked up, and no boost leaks that I can tell (IC piping wasn't even touched since the JDM twins). Any suggestions?This message will self destruct
10-13-2012, 08:32 PM #2
I did notice that the USDM twins had different vacuum hardlines, so I just used the JDM hardlines and hooked all vacuums up as they where on the JDM's. Looking at the USDM vacuum diagram, it still seems the JDM vac lines route to the same places.This message will self destruct
10-13-2012, 09:33 PM #3
10-13-2012, 10:43 PM #4
IC piping loose clamp?RIP Les Grover
* WANTED mint '84 P-type, any color, no mods, manual trans *
10-14-2012, 12:22 AM #5Member
- Join Date
- Sep 2012
^ its almost always that. Check all your IC piping @ the Intercooler, and at Intake/Turbo inlet.
BTW, you got any spare USDM cams? <3
10-14-2012, 12:58 AM #6
double check for boost leaks, my 1jz kept blowing off the vac lines behind the intake. My turbos are going out too but still build about 8-9 psi82 L Type
10-14-2012, 04:35 AM #7
I will deff check all these things, but It will be a recheck, recheck! As for the open wastegate, from my research I am seeing that I would at least get to 5PSI...., I am getting nothing... I have not touched the intercooling piping since the swap (before it boosted fine), but I am imagining that even with a boost leak I would hit some kind of PSI, not 0-0.5. The complicated twin setup makes me believe that it is a vacuum problem, but my vacuums seems to be ok, unless I somehow swapped the 4 vacuums that run behind the engine that I cannot see where they go to.This message will self destruct
10-14-2012, 11:27 AM #8
sounds like a split i/c coupler somewhere. but also, i thought the usdm turbos had different vsv's and wouldnt work properly when controlled b a jdm ecu? thought they had to be rigged for ttc? i havent really looked into it much though. wont even be using my jdm twins.
10-14-2012, 04:18 PM #9
Interesting, I have never heard that the VSV's where diff... However I am using the JDM VSV's with the USDM twins since they did not come with these twins... Urgh, this is annoying, it really does seem to be a vacuum problem or IC.This message will self destruct
10-14-2012, 07:26 PM #10
I had a problem similar to is way back when a ran twins..two actually, I blew the rear turbo(not your problem here) I also blew the intake mani gasket..how's yours.? I'm sure it was fine before the twin swap, but I thought I'd throw it out there. Good luck finding the problem..my $ is on a leak somewhere.FOR SALE $20k AND SHE IS YOURS.
'83 P-Type 2JZ "Wicked Felina"
668whp/627wtq@27psi on E85
483whp/442wtq@13psi on E85
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