Yes it is very possible for the injector assembly to be at fault and it is fairly common.However I will post a procedure to convert the system for more reliability at usually less expense.You may also want to remove the distributor and look to see if the drive gear is apple cored.This will not account for the lean condition but may attribute to the misfire code.Change the fuel filter no matter what your pressure is because the volume can be low and pressure still be ok.This is the procedure and parts list to convert to mpfi.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
Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
FIGURE Figure 1(c)
(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
Remove the Fuel Meter Body bracket and discard. Install the new bracket as shown in Figure 1.
FIGURE Figure 2(c)
(1) Cyl. #1 tube
(2) Cyl. #2 tube
(3) Cyl. #3 tube
(4) Cyl. #4 tube
(5) Cyl. #5 tube
(6) Cyl. #6 tube
(7) MFI Fuel Meter Body
Position Fuel Tubes of MFI Fuel Meter Body as shown in Figure 2. 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. See Figure 2.
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 as shown in Figure 2. 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.
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.
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.
Lubricate the Fuel Meter Body Upper Manifold O-ring (orange in color) with clean engine oil.
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).
Remove Upper Intake Manifold plenum and SFI Fuel Meter Body according to Service Manual Procedures.
Remove the Fuel Meter Body bracket and discard. Install the new bracket.
FIGURE Figure 3(c)
(1) Cyl. 2, 4, 6 and 8 tubes
(2) Fuel Inlet
(3) Cyl. 1, 3, 5 and 7 tubes
(4) Fuel Pressure Regulator
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.
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.
(1) Cylinders 6 & 8
(2) Fuel Pressure Regulator
(3) Cylinders 2 & 4
(4) Cylinders 5 & 7
(5) Cylinders 1 & 3
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.
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.
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.
Lubricate the Fuel Meter Body Upper Manifold O-ring (blue in color) with clean engine oil.
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.
Parts Information
Cleaning Procedure Parts
Part Number
Description
12345382
Threadlock
1050002
Top Engine Cleaner (U.S.)
992872
Top Engine Cleaner (Canada)
12345104
Port Fuel Injector Cleaner (U.S.)
10953467
Port Fuel Injector Cleaner (Canada)
CSFI to MFI Conversion Parts
Part Number
Description
12568332
V-6 MFI Assembly
88894355
V-6 Bracket
17113215
V-6 Seal Kit
93441235
V-8 MFI Assembly
17113206
V-8 Seal Kit
93442096
V-8 Bracket
