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Location:
Preston
Registered:
June 2002
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 1JZ Boost problems
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Mon, 26 August 2002 22:27
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I had a Profec B installed yesterday, and now it cuts out constantly. Im guessing this is the boost cut, but the controller was set to 12psi on the HI mode. On LO it ran fine for a while and then the same thing started happening. Now if i turn it off all together, it still cuts out then. They asked me to take it back to them to fix it, but Im hoping maybe some of you guys might have some ideas about how to fix this?????
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Location:
Canberra
Registered:
May 2002
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Re: 1JZ Boost problems
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Tue, 27 August 2002 00:57
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hey dude,
What is Profect B?? and what sort of boost controller do u use? I'm about to get a single stage boost controller for mine, but im not too sure how to hook it up with the twin turbo's and actuators. Is it just a matter of T pieces?
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Location:
Preston
Registered:
June 2002
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Re: 1JZ Boost problems
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Tue, 27 August 2002 01:00
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The Profec B is Trust's Electronic boost controller. Both pressure lines were T'd into 1 going into the controller, then split back into 2 afterwards.
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Location:
Preston
Registered:
June 2002
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Re: 1JZ Boost problems
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Tue, 27 August 2002 05:32
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One more quick question, where on a 1jz should a boost guage be plugged into?
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Location:
Sydney
Registered:
May 2002
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Re: 1JZ Boost problems
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Tue, 27 August 2002 12:55
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If you want to measure the boost being generated by the turbos, plumb it into the turbos side.
If you want to measure the boost reaching the manifold, plumb it into the intake manifold.
Usually 1.5 to 3 psi drop across the SMIC.
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I supported Toymods
Location:
Perth WA
Registered:
May 2002
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Re: 1JZ Boost problems
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Wed, 28 August 2002 15:18
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Check that you aren't getting a pressure leak on the boost control lines. Are all the connectors to wastegate and boost controller tight?
Maybe the profec has been set at some inappropriate "auto learning" level, and the duty cycle for the boost control solenoid/stepper has crept higher than when you started. The Auto learn setting for my AVC-R is not the best and relies on sensing a continuous, consistent level of boost for the duty cycle it picks out as appropriate for the boost pressure. This is only achievable really on dyno, or by flooring it on the road at warp speeds. The boost controller may also have adjustments for how aggressively you want boost to build up. If the initial duty cycle is set too high, there is boost overshoot, before the boost controller senses this and lets up on the boost control valve/solenoid. This overshoot may be enough to trigger fuel cut even on low settings.
(BTW I heard that Profecs use a stepper motor to adjust the pressure feedback to the wastegates? Correct me if I'm wrong)
The simplest way to check for boost overshoot is to have a friend looking at the boost gauge, or using a boost gauge with a max boost setting, then flooring it. You will find that boost spikes higher than the set level at the controller for some microseconds, before it comes back down. Do not do this youself because you need to be watching the road when travelling at warp speed!
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