16101-ZW4-D21 Honda SEE PART DETAILS - SUP; CARBURETOR ASSY. (#1,#2) (Honda Code 5686837).

Probable Causes
Diagnostic codes
Parameters in the Electronic Control Module (ECM)
Air intake system or exhaust system
Valve lash
Turbocharger
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinderRecommended Actions
Note: Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
Note: Certain diagnostic codes and/or event codes may cause poor performance. Refer to in the electronic service tool.
A. Use the electronic service tool to check for active or logged codes.
Engine Derate or Diagnostic Codes
Result: A diagnostic code is present.
Troubleshoot the code. Refer to Troubleshooting, "Diagnostic Trouble Codes"
Result: A diagnostic code is not present.
Proceed to Test Step 2.
2. Parameters in the Electronic Control Module (ECM)
A. Use the electronic service tool to verify that the correct parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Parameters
Result: The parameters are not correct.
Input the correct parameters. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Result: The parameters are correct.
Proceed to Test Step 3.
3. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped. Replace a plugged air filters. Refer to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System - Inspect"
Restrictions
Result: There are restrictions in the air inlet or exhaust system.
Make the necessary repairs, Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for additional information.
Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 4.
4. Valve Lash
A. Check the valve lash. Refer to Systems Operation, Testing, and Adjusting, "Engine Valve Lash - Inspect/Adjust".
Valve lash
Result: The valve lash is not set correctly.
Set the valve lash. Refer to Systems Operation, Testing, and Adjusting, "Engine Valve Lash - Inspect/Adjust" for the correct procedure.
Result: The valve lash is correct.
Proceed to Test Step 5.
5. Turbocharger
Note: The turbocharger that is installed on the engine is a non-serviceable item. If any mechanical fault exists, then the faulty turbocharger must be replaced.
A. Ensure that the mounting bolts for the turbocharger are tight.
B. Check that the oil drain for the turbocharger is not blocked or restricted.
C. Check that the compressor housing for the turbocharger is free of dirt and debris. Make sure that the housing is not damaged.
D. Check that the turbine housing for the turbocharger is free of dirt and debris. Make sure that the housing is not damaged.
E. Check that the turbine blades rotate freely in the turbocharger.
F. Ensure that the wastegate on the turbocharger is adjusted correctly. Refer to Systems Operation, Testing, and Adjusting, "Turbocharger - Inspect". If the wastegate actuator is faulty, replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Turbocharger
Result: There is a fault on the turbocharger.
Repair the turbocharger or replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Result: The turbocharger is OK.
Proceed to Test Step 6.
6. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
Low compression
Result: Low compression is recorded on one or more cylinders.
Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Make any repairs, as necessary.
Result: No faults found.
Proceed to Test Step 7.
7. Electronic Unit Injectors
A. Use the electronic service tool to check for active diagnostic codes that relate to the electronic unit injectors.
Diagnostic codes
Result: There are active diagnostic codes for the fuel injectors
Troubleshoot the active diagnostic codes. Refer to Troubleshooting, "Diagnostic Trouble Codes"
Result: There are no active diagnostic codes for the fuel injectors.
Proceed to Test Step 8.
8. Individual Malfunctioning Cylinders
A. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine.
Cylinders
Result: There is not a noticeable change in the sound of the engine for at least one cylinder.
Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
Result: There is a noticeable change in the sound of the engine for each cylinder.
Contact the Dealer Solution Network (DSN).