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!
Wed, 28 August 2002 15:18
