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Strange second turbo problem : won't kick in before 4th gear


florian

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Hi there! I come here because i did not found a logical answer to this problem.

 

One of my friend has a six speed manual supra, twin turbo, and from 1st gear to 3rd gear the second turbo never come in... from 4th to 6th, no problems, it runs normally.

 

Someone got an idea?

 

Thanks

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Guest Evlc36

IACV VSV - had same on my Aristo, when it got hot it stopped working, and 2nd turbo would not come online in first or second, but I guess the force applied when in 3rd (auto box) was enough to manually force the IACV flap open and let 2nd turbo do its job.

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Control circuit vacuum or pressure leak, or malfunctioning solenoid would be my first line of investigation. Although I am tempted, having seen the standard of driving in France, to suggest his issue may be a blessing in disguise ;)

I am pretty you were driving the wrong way!!!! :)

 

With a compressor i tried to put some air on the "circuit", no problem with the intake to turbo, but from turbo to intercooler, IACV is leaking. Is it normal? I can see a breather on it, but it really leaks all the air.

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:) I meant to check all the small vacuum and pressure pipes, not the turbos to plenum, via the intercooler stuff, although it's best to give those a REALLY good tug and looking at. I would make sure all the small hoses are soft and supple and in no danger of having tears or splits. Then check each solenoid with a 12 volt source and a Mityvac.

 

 

The idle control valve will be left in a semi open state on engine shut down, as will some of the intake valves, you will not be able to pressurise the plenum itself, you need to bung up the hose to the throttle valve and pressurise the hose down to the IC.

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