Or this TSB misfire is due to clogged up fuel injector
Document ID# 1968712
Chevrolet Corvette
Subject: Various Driveability Symptoms Due to Clogged Fuel Injectors, MIL/SES DTCs P0171, P0172, P0174, P0300, P1174, P1175 (Clean Fuel Injectors and/or Perform Injector Test with AFIT - CH-47976) #03-06-04-030D - (05/03/2007)
Models: 2000-2009 GM Passenger Cars and Light Duty Trucks (Including Saturn) with 2.2L, 2.4L, 2.8L, 3.1L, 3.4L, 3.5L, 3.8L, 3.9L, 4.2L, 4.3L, 4.8L, 5.3L, 6.0L, 6.2L or 8.1L Engine (VINs F, D, 4, 5, T, 8, J, E, H, L, 6, K, 1, 2, R, W, S, X, V, T, M, N, U, H, Y, 8, G -- RPOs L61, LN2, L43, LD9, LK5, LG8, LA1, LX5, LX9, LZ4, LZE, L52, L36, L67, L26, LZ9, LZ8, LGD, LL8, LU3, LR4, LM7, LH6, LQ9, LQ4, LS2, L76, L92, L18) and MULTEC® 2 Fuel Injectors
Condition
Some customers may comment on any of the following various driveability symptoms:
• Extended Crank Time
• Hard to Start
• MIL/SES Illuminated with DTCs
• Hesitation
• Lack of Power
• Surge or Chuggle
• Rough Idle
• Light or Intermittent Misfire
Cause
Due to various factors, the fuel injectors may become restricted. Extensive testing has demonstrated that fuel related issues are the cause of clogged injectors. At this point, no specific fuel, fuel constituent, or engine condition has been identified as causing the restriction. The restriction causes the engine to operate at a lean air fuel ratio. This may either trigger the MIL to illuminate or the engine to develop various driveability symptoms.
Correction
Fuel injector restrictions, deposits can be cleaned on the vehicle using the following procedure. Under NO circumstances should this procedure be modified, changed or shortened. As a long term solution, and to prevent reoccurrence, customers should be encouraged to use Top Tier Detergent Gasoline . For further information on Top Tier detergent gasoline and fuel retailers, please refer to the following Corporate Bulletin Numbers:
• 04-06-04-047G (U.S. Only)
• 05-06-04-022C (Canada ONLY)
Notice: GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent approved for use with General Motors fuel system components. Other injector cleaners may cause damage to plastics, plated metals or bearings. General Motors has completed extensive laboratory testing of GM Upper Engine and Fuel Injector Cleaner, and can assure its compatibility with General Motors fuel system components, as long as the cleaning procedure is followed correctly.
Injector Cleaning Procedure
The following tools, or their equivalent, are required:
• CH-47976 Active Fuel Injector Tester (AFIT)
• J 35800-A Fuel Injector Cleaner
• J 37287 Fuel Line Shut-off Adapter
• J 42964 Fuel Line Shut-off Adapter
• J 42873 Fuel Line Shut-off Adapter
• * One bottle of GM Upper Engine and Fuel Injector Cleaner, P/N 88861802 (in Canada, P/N 88861804)
• * One bottle of GM Fuel System Treatment Plus, P/N 88861011 (in Canada, P/N 88861012)
Active Fuel Injector Tester (AFIT- CH-47976)
Some dealers may not have an Active Fuel Injector Tester (AFIT- CH-47976). Dealers can contact 1-800-GM-TOOLS (1-800-468-6657) to order an AFIT- CH-47976. Dealers still can test the fuel injectors without an AFIT. Refer to Fuel Injector Diagnosis (w/ J 39021 or Tech 2®) in SI.
Important: As mentioned in the AFIT User Guide, vehicles that are not listed in the AFIT menu can still be tested with the AFIT. Depending on the model, it may be possible to enter the previous model year and proceed with testing using the DLC connection. If this is not possible on the model that you are working on, it will be necessary to use the direct connection method outlined in the AFIT User Guide (See Pages 17-31).
General Motors recommends that the Active Fuel Injector Tester (AFIT) be used in testing fuel injectors. If the SI diagnostics do not isolate a cause for this concern, use the Active Fuel Injector Tester (AFIT - CH-47976) to perform an "Injector Test" as outlined in the AFIT User Guide.
The AFIT "Injector Test" measures the flow characteristics of all fuel injectors, which is more precise when compared with the standard Tech 2® fuel injector balance test. As a result, the AFIT is more likely to isolate the cause of a P1174 DTC (for example: if it is being caused by a fuel injector concern).
The CH-47976 (Active Fuel Injector Tester - AFIT) can also be used to measure fuel pressure and fuel system leak down. Also, as mentioned in the P1174 SI diagnosis, if the misfire current counters or misfire graph indicate any misfires, it may be an indicator of the cylinder that is causing the concern. Refer to Fuel Injector Diagnosis (w/CH-47976) in SI for additional instructions.
Injector Cleaning Procedure
Notice: GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent recommended. DO NOT USE OTHER CLEANING AGENTS AS THEY MAY CONTAIN METHANOL, WHICH CAN DAMAGE FUEL SYSTEM COMPONENTS. Under NO circumstances should the GM Upper Engine and Fuel Injector Cleaner be added to the vehicle fuel tank.
Do not exceed the recommended cleaning solution concentration. Testing has demonstrated that exceeding the recommended cleaning solution concentration does not improve the effectiveness of this procedure.
Important: Vehicles with less than 160 km (100 mi) on the odometer should not have the injectors cleaned. These vehicles should have any out of specification injectors replaced.
For 4, 5 and 6 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) mixed with 420 ml (14 oz) of regular unleaded gasoline.
For 8 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) of Upper Engine and Fuel Injector Cleaner mixed with 420 ml (14 oz) of regular unleaded gasoline. This procedure will need to be repeated for a second time for an 8 cylinder engine (8 cylinder engines receive 960 ml total fluid - 120 ml (4 oz) of Upper Engine and Fuel Injector Cleaner and 840 ml (28 oz) of gasoline.
Fill the injector cleaning tank with regular unleaded gasoline. Be sure to follow all additional instructions provided with the tool.
Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch connector, if equipped.
Turn the ignition to the OFF position.
Relieve fuel pressure and disconnect the fuel feed and return lines at the fuel rail. Plug the fuel feed and return lines coming off the fuel rail with J 37287, J 42873 or J 42964 as appropriate for the fuel system.
Connect the J 35800-A to the vehicle fuel rail.
Pressurize the J 35800-A to 510 kPa (75 psi).
Start and idle the engine until it stalls, due to lack of fuel. This should take approximately 15-20 minutes.
Turn the ignition to the OFF position.
Disconnect the J 35800-A from the fuel rail.
Reconnect the vehicle fuel pump relay and oil pressure switch connector, if equipped.
Remove the J 37287, J 42873 or J 42964 and reconnect the vehicle fuel feed and return lines.
Start and idle the vehicle for an additional two minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.
Pour the entire contents of GM Fuel System Treatment Plus (P/N 88861011 [in Canada, P/N 88861012]) into the tank and advise the customer to fill the tank.
Review the benefits of using Top Tier Detergent gasoline with the customer and recommend that they add a bottle of GM Fuel System Treatment Plus to the fuel tank at every oil change. Regular use of GM Fuel System Treatment Plus should keep the customer from having to repeat the injector cleaning procedure.
Road test the vehicle to verify that the customer concern has been corrected.
