Code 57, Boost Control Problem, (VIN 1)
Under most conditions, PCM commands boost control solenoid to operate at a 100 percent duty cycle (on) to allow full boost upon demand; however, if reverse gear is selected, PCM detects rapid deceleration, or if engine load is extremely high, reduced boost pressure is desired. Under these conditions, PCM commands boost control solenoid to operate at zero percent duty cycle (off), which opens by-pass valve to reduce boost pressure by recirculating it back through supercharger inlet. If PCM detects a malfunction in boost control system that causes engine torque to be too high (by-pass valve not opening), it will illuminate SERVICE ENGINE SOON light and set Code 57.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- If boost control driver circuit becomes shorted to ground between solenoid and PCM, by-pass valve will remain closed when PCM attempts to command it open. This could cause an overboost condition during high engine load situations.
- No inlet vacuum to by-pass valve actuator may cause by-pass valve to remain closed during deceleration. This condition will be perceived as a sail-on condition, possibly accompanied by a rough idle.
- This step checks for a sticking boost control solenoid.
NOTE:
Prior To Performing This Chart, Verify Presence Of At Least 15 In. Hg. Vacuum To By-Pass Actuator Solenoid With Engine Idling. Also Verify Lines Are Not Plugged. Repair Any Vacuum Supply Problems.