• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
Cylinder | 1 | 2 | 3 | 4 |
---|---|---|---|---|
First Reading | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) |
Second Reading | 215 kPa (31 psi) | 201 kPa (29 psi) | 230 kPa (33 psi) | 215 kPa (31 psi) |
Amount Of Drop | 165 kPa (24 psi) | 179 kPa (26 psi) | 151 kPa (22 psi) | 165 kPa (24 psi) |
Average Range: 156-176 kPa (22.5-25.5 psi) | Injector OK | Fuel Injector - Too Much Pressure Drop | Faulty Injector - Too Little Pressure Drop | Injector OK |
The scan tool is first used to energize the fuel pump relay. The fuel injector tester is then used to pulse each injector for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
• | Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition. |
• | Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition. |
• | Perform the fuel injector balance test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions. |
J 39021 Fuel Injector Coil and Balance Tester
⇒ | If the ECT is greater than 94°C (201°F) allow the engine to cool before proceeding. |
⇒ | If the fuel pressure is not within the specified range refer to Fuel System Diagnosis for further diagnosis of the fuel system. |
⇒ | If the fuel pressure decreases more than 34 kPa (5 psi) refer to Fuel System Diagnosis for further diagnosis of the fuel system. |
Notice: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding.
Important:
• | Repeat this step for each fuel injector in order to obtain a pressure drop value for each fuel injector. |
• | The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. |
⇒ | If the difference between any individual pressure drop and the average pressure drop is more than 20 kPa (3 psi), replace the fuel injector. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.