MHD and ATR N54 Custom Tuning
335i, 335is, 335xi, Z4, 1M
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Q-Logic is a tuning method and approach from BQ Tuning to deliver better and optimized performance out of COBB ATR or MHD for your BMW N54. Q-Logic is an overboost function allowing boost to overshoot the boost ceiling or boost target limit of 18.4 PSI up to 21 PSI keeping the overall system load in check and not exceeding or overshooting Load Target . This is mostly applicable to cars in which the boost ceiling cannot be raised.

PID manipulation allows absolute control of “overboost” within the  TMAP sensor’s range limit of 36.3 psi “absolute boost pressure” or abs boost means. It is highly recommended to upgrade the N54 TMAP sensor to a 3.5 bar or 4 bar TMAP sensors to avoid loss of resolution after 20 PSI and to maintain proper PID control of boost that is intended.

How is this done? The TPS or the throttle closure functionality is reconfigured to activate ie a throttle closure occurrence when boost tries to exceed more than 36.0 PSI abs boost means in order to keep boost on the DME’s radar. Factor settings throttle closure occurs if boost is even slightly exceeds the boost target. So this has been readjusted to allow up to 2.5 PSI max overboost over the boost target. If more than 3 psi is seen by the DME throttle closure will be triggered.

Next the PID’s are calibrated to curve boost back to its set point as a tapper, rather than using TPS which has a tendency to aggravate timing corrections.

 Q-Logic optional  for FBO N54 cars the boost ceiling cannot be raised which have the mods to support the additional boost and power.

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