Page 262 - Understanding Automotive Electronics
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2735 | CH 7  Page 249  Tuesday, March 10, 1998  1:15 PM



                                         DIGITAL ENGINE CONTROL SYSTEM                                     7





                    Figure 7.15
                    Fast Correction
                    Spark Advance









                                                         FPO















                                         one degree of spark advance to cause knocking, more than one degree must be
                                         removed to eliminate knocking). The fast correction scheme is depicted in
                                         Figure 7.15.
                                              In the slow correction scheme (Figure 7.16), spark advance is decreased by
                                         one (or more) degree each time knock is detected, until no knocking is
                                         detected. The spark advance proceeds in one-degree increments after many
                                         engine cycles.

                    Figure 7.16
                    Slow Correction
                    Spark Advance



                                                         FPO















                                         UNDERSTANDING AUTOMOTIVE ELECTRONICS                            249
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