Ignition timing is a pivotal factor in the performance of a vehicle’s engine. The engine’s retard timing develops when fuel ignition occurs after the manufacturer's specification. When a retarded condition is detected, it may be a daunting task to diagnose every timing related component. Spend some time, correct the timing, and save some time using this Real Fix.
2000, Chevrolet S10 Pickup, 4.3L
P1345, Replaced Crankshaft Position Sensor
The customer states the check engine light is on.
Connected a scan tool and found code P1345 - Camshaft/Crankshaft Correlation Error. Monitored the live data with the engine running and found the ignition timing parameter was excessively retarded. Performed an inspection of the ignition distributor and found no obvious faults. Connected a lab scope to the crankshaft position (CKP) sensor and camshaft position (CMP) sensor signal wires and simultaneously monitored both of the waveforms. Found both the CKP sensor and CMP sensor waveforms were present, but the CKP sensor waveform pattern was erratic. Visually inspected the CKP sensor wiring harness, and found no obvious signs of damage. Key on, engine off, used the multi-meter to check for the presence of voltage and ground at the CKP sensor, and found both were present. At idle, backprobed the CKP sensor and monitored the sensor signal on the lab scope. Found the CKP sensor signal was erratic. This indicated the CKP sensor was faulty.
Replaced the crankshaft position sensor, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.
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