P3656moderate severityPowertrain
Port and Direct Injection System Imbalance
on 2017 GMC Acadia 3.6L V6 · FWD
What this code means
In dual-injection systems (combined port and direct injection), the balance between PFI and GDI fueling is incorrect.
Symptoms
- Check Engine Light
- Rough idle
- Knock or ping under load
- Poor emissions
- Fuel economy reduced
- Cold start misfires
Common causes
- Port injector partial blockage
- GDI injector drift
- Fuel pressure imbalance between systems
- PCM fuel strategy calibration error
- Intake runner flap affecting port injection
Diagnostic steps
- Compare port vs direct injection fuel trim data
- Test individual port injector flow
- Test GDI injector flow rates
- Monitor knock sensor activity
- Check intake runner valve operation
Repair notes
Clean or replace affected injectors. Recalibrate fuel split strategy if software update is available. Check intake runner valves.
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Other Powertrain codes on this vehicle
P0001
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P0002
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P0003
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P0004
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P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
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P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1