Ran across the TSB that describes the misfire, cleaning and replacement with MFI injectors.
GM Data wrote:Rough Idle After Start, And/Or A Service Engine Soon (SES) Light (Unstick And Clean Central Sequential Fuel Injection (CSFI) Poppet Valves or Convert to MFI) #00-06-04-003B - (Jan 30, 2003)
Rough Idle After Start, And/Or A Service Engine Soon (SES) Light (Unstick And Clean Central Sequential Fuel Injection (CSFI) Poppet Valves or Convert to MFI)
1995-2002 Chevrolet and GMC S/T Models
1996-2002 Chevrolet and GMC C/K, M/L, G, P Models
1996-2001 Oldsmobile Bravada
1999-2000 Cadillac Escalade
with 4.3L, 5.0L or 5.7L Engine (VINs W, X, M, R -- RPOs L35, LF6, L30, L31)
Except 2002 VIN X -- RPO LU3 Models
This bulletin is being revised to update the Correction and Warranty Information. Please discard Corporate Bulletin Number 00-06-04-003A (Section 06 -- Engine).
Condition
Some customers may comment on rough idle after start-up, especially if the vehicle has sat overnight. These symptoms may be intermittent. The Service Engine Soon (SES) light may also be illuminated. Current misfire or history misfire codes may be detected with the Tech 2 scan tool.
Cause
A deposit build-up on the CSFI poppet valve ball and/or seat may cause the poppet ball to stick open or closed. In either case, the specific cylinder will be mis-fueled, resulting in a cylinder mis-fire condition.
Correction
A new injector unsticking and cleaning process has proven to be effective in restoring poppet valves to an "as new" condition. CSFI injector replacement should NOT be considered as a correction for this customer concern.
Check the vehicle history to determine if the vehicle is returning for a second fuel system repair for this condition. If the fuel system has been repaired for this condition previously, then inform the customer that an alternate fix is available. A new MFI fuel system has been developed that will back service the CSFI fuel system. The MFI fuel system eliminates the CSFI poppet valve ball and seat. The CSFI fuel system will need to be replaced as a unit. Refer to Central SFI to MFI Conversion instructions in this bulletin.
Notice
Individual CSFI injectors can not be replaced with MFI injectors. The entire CSFI fuel meter body will need to be replaced. The bracket used to retain the injectors in the fuel meter body is different between the CSFI and MFI unit. The unit may not seal if you mix injectors. Severe engine damage could result.
Cleaning the CSFI injectors is the preferred repair. The CSFI unit should not be replaced until cleaning has been attempted. If the vehicle should return for the same repair, then the CSFI unit can be replaced with an MFI unit. If the vehicle is out of warranty, the customer should be given the option of which fix to pursue.
Important
"GM of Canada" dealers require District Service Manager approval prior to replacing the CSFI unit with a MFI unit under warranty.
The first step of this process is to use the J 41413 Evap Pressure/Purge Station, in conjunction with the J 44466-10 pressure regulator/hose assembly, to provide the required high pressure (150 psi) source to perform the unsticking procedure. The J 39021 fuel injector tester and accessories provide the means to "energize" the injector. Some later model-year vehicles may utilize the Tech 2® to "energize" the injectors.
The second step of this process is to run the engine on a solution of 10% Top Engine Cleaner and 90% gasoline. This will effectively clean any deposits from the ball and seats of the poppets. It is very important that the engine fuel system is separated from the vehicle fuel system. Top Engine Cleaner may have detrimental effects on the fuel pump.
Cleaning Procedures
This procedure should be performed before any attempt to convert the fuel system to MFI.
S/T and C/K Truck
1. Loosen the fuel filler cap to relieve vapor pressure in the fuel tank.
2. Remove the Positive Crankcase Ventilation (PCV) clean air tube from the air inlet tube and set aside.
3. Remove the bonnet and inlet tube from the throttle body.
4. Remove the brake booster vacuum hose and connector from the intake manifold.
5. Remove the electrical connector from the CSFI fuel metering body.
6. Remove ignition wires 1, 3, 5, from the distributor cap.
7. Remove the fuel line bolt at the rear of the intake manifold.
8. Relieve the fuel system pressure at the service fitting on the fuel line. Use a shop towel to contain any fuel that may exit the service fitting.
9. Remove the nuts and clamp from the fuel pipe.
10. Remove the fuel pipes from the metering body. Be careful not to disturb the O-rings, washer, and spacer in the metering body.
11. Install the J 44466-12 and the J 44466-13 to the metering body and tighten. Make sure that the fuel pipe O-rings, washer, and spacers are present and in their proper position.
12. Install the J 44466-11 , clamp , and J 44466-13 to the fuel pipe and tighten.
13. Obtain the J 41413, close the valve on the tank, and remove the regulator assembly.
14. Install the J 44466-10 to the J 41413 tank . The J 44466-10 regulator is preset to 150 psi.
15. Connect the J 44466-10 hose to the J 44466-12.
16. Install the J 39021 Injector/Coil Balance Tester, the J 39021-210 Injector Tester Adapter Box, and J 39021-301 V6 Fuel Injector Test Adapter or J 39021-302 V8 Fuel Injector Test Adapter to the metering body electrical connector.
17. Adjust the amperage selector switch on J 39021 to 0.5 amps.
18. Open the valve on the tank.
19. Open the valve on the J 44466-10 to pressurize the fuel system. The minimum pressure required on the gauge is 150 psi. If 150 psi is not obtained, the tank must be refilled prior to performing this procedure.
20. Close the valve on the J 44466-10.
21. Energize one injector using the J 39021. Observe a pressure drop on the gauge (6) and verify the injector/poppet valve operation. An injector/poppet that is "stuck" and not operational will have no pressure drop on the gauge. If an injector remains "stuck", repeat the procedure multiple times (as required) until the injector is operational.
22. Repeat steps 19, 20 and 21 for each individual injector to verify that all injector/poppet valve assemblies are "unstuck" and functional.
23. Shut off pressure valve on the tank of the J 41413.
24. Bleed off the pressure at the J 44466-10.
25. Disconnect and remove the J 44466-10 from the J 44466-12, and the J 41413.
26. Remove the J 39021-301 or J 39021-302, J 39021-210, and J 39021 from the metering body.
27. Install the vehicle electrical connector to the metering body.
28. Install the brake booster vacuum hose and connector to the intake manifold.
29. Install ignition wires 1, 3, 5, to the distributor cap.
30. Install the air inlet bonnet to the throttle body, tighten the wing-nut.
31. Install the PCV fresh air tube to the air inlet tube.
32. Obtain J 35800-A. Make sure the valve at the bottom of the canister is closed.
33. Remove the canister top and add 24 ml (0.8 fl.oz.) Top Engine Cleaner, P/N 1050002 (Canada P/N 992872), to the canister.
34. Fill the remainder of the canister with regular unleaded gasoline and install the canister top.
35. Suspend J 35800-A from a convenient underhood location.
36. Connect the hose from J 35800-A to the service port on the J 44466-12.
37. Open the valve at the bottom of J 35800-A.
38. Connect a "shop air" source to the fitting at the top of J 35800-A and adjust the regulator to 75 psi.
39. Start the vehicle. It may be necessary to re-adjust the J 35800-A pressure regulator to maintain 75 psi.
40. Let the vehicle run at idle until the canister is empty and the vehicle stalls.
41. Remove the shop air supply from J 35800-A.
42. Depressurize the J 35800-A.
43. Disconnect the J 35800-A hose from the J 44466-12.
44. Remove the PCV clean air tube from the air inlet tube and set aside.
45. Remove the bonnet from the throttle body, and set aside.
46. Remove ignition wires 1, 3, 5, from the distributor cap.
47. Remove the brake booster vacuum hose and connector from the intake manifold.
48. Bleed the residual pressure from the J 44466-12.
49. Remove J 44466-13 and J 44466-12 from the metering body.
50. Remove J 44466-13 , clamp , and J 44466-11 , from the fuel pipe.
51. Install the fuel pipe to the metering body. Make sure that all of the O-rings and , washers , and spacers are present and in their proper position.
52. Install the clamp and nuts.
Tighten the nuts to 3 N·m (27 lb in).
53. Apply threadlock, P/N 12345382, or equivalent to the threads of the fuel pipe bolt (4). Install the bolt.
Tighten the fuel pipe bolt to 6 N·m (53 lb in).
54. Install the brake booster vacuum hose and connector to the intake manifold.
55. Install the bonnet and air inlet tube to the throttle body.
56. Install the PCV fresh air tube to the inlet duct.
57. Install ignition wires 1, 3, 5, to the distributor cap.
58. Add one ounce of Port Fuel Injector Cleaner, P/N 12345104 (Canada P/N 10953467), to the vehicle fuel tank for each gallon of gasoline estimated to be in the tank. Instruct the customer to add the remainder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill-up. Further recommend that Port Fuel Injector Cleaner be added to the fuel tank every 3000 miles (4800 km) particularly if the vehicle is not started and driven every day. Inform the customer that the Port Fuel Injector Cleaner is not to be used at every fill up but may be reapplied every 3000 miles (4800 km).
59. Tighten the fuel tank filler cap.
60. Start the vehicle and check for fuel leaks.
61. Using the Tech 2® scan tool, check for any stored Powertrain DTC codes. Clear codes as required.
62. Disconnect the Tech 2® Scan tool.
63. Advise the customer to change brands of fuel.
Central SFI to MFI Conversion Instructions
This procedure outlines the steps required to replace the existing Central SFI Fuel System with a new MFI (Multiport Flexible Injection) Fuel System. Be sure to use the appropriate year and model Service Manual for proper disassembly and re-assembly procedure(s).
Important
Cleaning the CSFI injectors is the preferred repair. The CSFI unit should not be replaced until cleaning has been attempted. If the vehicle should return for the same repair, then the CSFI unit can be replaced with a MFI unit. If the vehicle is out of warranty, the customer should be given the option of which fix to pursue.
V6 Engines
1. Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
2. Remove the Fuel Meter Body bracket and discard. Install the new bracket.
3. Position Fuel Tubes of MFI Fuel Meter Body. Tubes must be oriented away from the fuel pressure regulator end of the fuel meter body.
Notice
The number 3 Fuel Tube must be positioned behind the number 1 Fuel Tube to eliminate interference with the Upper Intake Manifold plenum when installed.
4. Insert the MFI Fuel Meter Body into the Fuel Meter Body Bracket on the Lower Intake Manifold being careful not to bind the Fuel Tubes. Make sure that the number three Fuel Tube is routed in behind number 1 and 5 Fuel Tubes. Push down firmly on the fuel meter body locking it into the bracket.
Notice
Use caution when inserting injectors into lower intake manifold to be sure the correct injector is being placed into the correct hole.
Injectors should not be removed once they have been installed.
Removal of injectors from the intake manifold may cause damage to the retaining lugs on the injector.
Important
The Injector holes are numbered on the Lower Intake Manifold. The injectors are numbered on the side of the Fuel Meter Body.
5. Insert the number 3 injector into the correct Injector hole in the Lower Intake Manifold first. Install the number 5 injector next and then number 1. This sequence must be followed correctly to prevent interference of the Fuel Tubes. Injectors 2, 4, and 6 are then installed.
6. Insure that the electrical connectors of the injectors are positioned so that they do not interfere with each other and are pointing towards the center of the Intake Manifold. If necessary, rotate the electrical connectors inboard.
Notice
Lack of lubrication will make installation of the Upper Intake Manifold plenum difficult and may cause damage to the O-ring.
7. Lubricate the Fuel Meter Body Upper Manifold O-ring (orange in color) with clean engine oil.
8. Inspect the Upper Intake Manifold plenum gasket and replace if necessary. Reinstall the Upper Intake Manifold plenum following the procedures outlined in the Service Manual.
Important
Lubricate the Fuel Inlet and Return Lines with clean engine oil before inserting them into the Fuel Meter Body.
Make sure that the Fuel Line Retaining Bracket is properly oriented with the tabs down.
V8 Engines
This procedure outlines the steps required to replace the existing Central SFI Fuel System with a new MFI (Multiport Flexible Injection) Fuel System. Be sure to use the appropriate year and model Service Manual for proper disassembly and re-assembly procedure(s).
1. Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
2. Remove the Fuel Meter Body bracket and discard. Install the new bracket.
3. Position Fuel Tubes of MFI Fuel Meter Body as shown in Figure 3. Fuel tubes 1, 3, 5, and 7 are oriented toward the fuel inlet side of the fuel meter body. Fuel tubes 2,4,6, and 8 are oriented toward the fuel pressure regulator side if the fuel meter body.
4. Insert the MFI Fuel Meter Body into the Fuel Meter Body Bracket on the Lower Intake Manifold being careful not to bind the Fuel Tubes. Push down firmly on the fuel meter body until the tabs snap into the bracket locking the fuel meter body in place.
5. Orient the fuel tubes to coincide with their corresponding cylinder. The fuel tubes are numbered on the side of the fuel meter body and the corresponding cylinder number is cast in the intake manifold.
Notice
Use caution when inserting injectors into lower intake manifold to be sure the correct injector is being placed into the correct hole.
Injectors should not be removed once they have been installed.
Removal of injectors from the intake manifold may cause damage to the retaining lugs on the injector.
Important
The Injector holes are numbered on the Lower Intake Manifold. The injectors are numbered on the side of the Fuel Meter Body.
6. Insert the fuel tubes into their corresponding holes in the intake manifold. Install tubes for cylinders 1, 3, 6 and 8 making sure that the injector electrical connectors are facing in toward the center of the manifold.
7. Insert fuel tubes for cylinders 2,4,5, and 7 in the same manner.
Important
When installing fuel tubes, it is important that the tubes are oriented properly to provide minimal interference when installing the upper intake manifold plenum. Intake holes for cylinders 2, 4, 5, and 7 are closer to the fuel meter body. It is necessary to cross tube 5 over tube 7 and tube 4 over tube 2 as shown in Figure 4.
Notice
Lack of lubrication will make installation of the Upper Intake Manifold plenum difficult and may cause damage to the O-ring.
8. Lubricate the Fuel Meter Body Upper Manifold O-ring (blue in color) with clean engine oil.
9. Inspect Upper Intake Manifold Gasket and replace if necessary. Reinstall the Upper Intake Manifold plenum following the procedures in the Service Manual.
Important
Lubricate the Fuel Inlet and Return Lines with clean engine oil before inserting them in the of the Fuel Meter Body.
Make sure that Fuel Line Retaining Bracket is properly oriented with the tabs down.
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