Jaguar XJ Check Engine Light On Repair Guideby Tacry J. Auto Diagnostic Tool
A 2006 Jaguar XJ sedan with a mileage of approximately 110,000 km and a 3.0 L V6 engine. The car was inspected and repaired due to the engine failure light.JLR SDD Mangoose
After the vehicle is picked up, the test is verified to be faulty, the ignition switch is turned on, the engine is started, the engine is started smoothly, and the engine fault light on the instrument panel is lit, and the fault phenomenon does exist. Connect the fault detector and retrieve the fault code. The fault code is "B2139 Data mismatch (received data does not match expected data)", which means that the password does not match; "P0171-00 System too lean (bankl)", The meaning is that the cylinder group 1 is too lean; "P0174-00 System too lean (bank2)", which means that the cylinder group 2 is too lean; "U1262 SCP 01850" Communications bus fault", which means SCP U1850) bus Communication failed.JLR Key Programmer
Analysis of the fault code shows that the fault codes associated with the fault phenomenon are P0171 and P0174. The relevant data stream is read. The data flow shows that the long-term fuel correction values of cylinder groups 1 and 2 at idle are 20.3%, the short-term fuel correction value of cylinder group 1 is 3.91%, and the short-term fuel correction value of cylinder group 2 is 5.47%. . However, when the accelerator pedal is depressed, the engine speed is increased. As the engine speed increases, the long-term fuel correction values of the cylinder groups 1 and 2 gradually return to normal, but the short-term fuel correction value of the cylinder group 2 is always larger than that of the cylinder group 1.
According to the above inspection results, combined with the maintenance experience, it is considered that there is a high possibility of leakage in the engine intake line. Considering that the short-term fuel correction value of the cylinder group 2 is always larger than that of the cylinder group 1, it is suspected that there may be a leak in the intake line on the side of the cylinder group 2. Then, the intake line on the side of the cylinder group 2 is inspected, and it is found that there is a leak in the intake switching valve on the side of the cylinder group 2. However, according to the maintenance experience, the leakage of the pipeline on this side does not make the long-term fuel correction value of the whole system significantly higher.
Next, the maintenance personnel inspected the activated carbon canister solenoid valve and found that the activated carbon canister solenoid valve was still open at idle speed. Disconnect the pipe connected to the activated carbon canister at the throttle valve, and grasp the interface on the throttle side by hand to observe the change of the long-term fuel correction value of the cylinder groups 1 and 2 at the idle speed, and find the long-term fuel of the cylinder groups 1 and 2. The correction value has changed to 18.8%. Although it has improved better than the previous test results, the air leakage fault has not been completely eliminated.
Check the various ports of the pipeline between the air filter and the intake manifold, no air leakage, and check the brake vacuum tube, the crankcase forced ventilation line, the fuel pressure regulating valve vacuum line and the activated carbon canister solenoid valve vacuum tube. Road, no abnormalities. Troubleshooting is deadlocked.
After careful consideration, the fault apparently has air that has not been counted in, causing the system to correct the amount of fuel injected. The maintenance personnel again inspect the intake line again. When the air cleaner was removed and the intake line between the throttle and the throttle was inspected, it was found that the back of the intake pipe was aged and cracked.
Troubleshooting: Replace the intake line and cylinder group 2 intake switching valve, commissioning, troubleshooting.
Created on Aug 12th 2018 21:02. Viewed 43 times.