Benz E200 check engine light, idle when the engine vibration, slow speed

by Tacry J. Auto Diagnostic Tool
A Mercedes E200 configuration 271EVO engine and 722.9 transmission, mileage of 131670km. The car to replace the oil filter base, 4 days after the engine fault light, and idle engine jitter, the vehicle speed slow.xtool x100 pro

Troubleshooting and troubleshooting
The car replaced the oil filter base, disassembled the intake manifold, according to the initial phenomenon of the fault to determine the following reasons: the intake system in a vacuum tube leak or not installed in place; intake manifold leak ; Throttle does not match well, or is not installed in place; ignition problem; xtool ez500 oil supply problem.

Because the car did not change the maintenance of the spark plug, VVDI MB Tool and the last into the store to check the spark plug attached to a lot of coke, and the phenomenon of burning the electrode, first with a new spark plug installed, the car after the engine or jitter. There is no problem with the spark plug connected to the diagnosis of the spark plug. Read the fault code: P0172 mixture (cylinder column 1) is too thick, the signal amplitude is greater than the maximum amplitude. The meaning of the fault code is the mixture is too thick, resulting in mixed gas is too thick because the main reason is too much fuel injection, too little intake or burning is not good. Follow the fault code to guide the actual value of the engine under idling conditions.VVDI Key Tool

The actual value of the rail pressure is 5440kPa (marked value is 4540 ~ 6540kPa), which will remove the problem of high pressure pump. Throttle downstream pressure sensor pressure value of 48.266kPa (standard value of 20 ~ 40kPa), the signal voltage is 1.0V (standard value is 0.5 ~ 0.7V). There are two reasons for its actual value: the sensor and its line problems; air intake system in a part of the leak. According to the circuit diagram to measure the sensor supply voltage of 5V, ground and signal lines are normal. Throttle upstream pressure sensor and the downstream pressure sensor, the two sensors are interchangeable, the actual value of the sensor is still incorrect, indicating that the sensor and its line is no problem. Next check the air intake system where there is no leakage,VVDI Key Tool.

In the first easy after the difficult principle, first check the intake system of each vacuum tube with or without leakage of the place, and then check the throttle, remove the throttle to see the seal is not damaged and crushed place, flap is not issued card , To save the throttle again after the replacement, with a diagnostic instrument to re-learn, taking into account the E-class 212 models in the diagnostic test when the voltage requirements are more stringent, when the battery voltage is lower than 11.6V when some of the elements of learning And the match may not succeed. Connected to the battery charger on the throttle to relearn, start the vehicle, the fault remains the same, remove the throttle problem,VVDI MB Tool. Then focus on checking the intake manifold, remove the intake manifold to see its seal is intact, no abnormalities, but also in the seal on the sealant, and then installed in accordance with the standard torque intake manifold. Start the car, the engine or jitter, throttle downstream pressure sensor actual value is not normal. Re-order ideas, starting from the air intake step by step careful investigation, see whether the missing part. When the rear of the air filter to check the intake pipe, found that as long as the pull out of the intake pipe connected to the secondary air jet pump hose (below),MB SD C4 the engine does not shake, and the actual value of the throttle downstream pressure sensor Also fell to the normal range. Put the handle near the hose, can obviously feel the warm air blowing, smell like the exhaust gas from the cylinder.

This tube is the secondary air jet pump inlet pipe, the secondary air jet pump is usually only in the coolant temperature between 10 ~ 60 ℃, the engine speed is less than 3000r / min, the engine is idle or part of the load. The secondary air jet pump draws fresh air from here and then switches the vacuum control secondary air injection valve from the intake manifold by the air pump changeover valve (Y32). The fresh air enters the row of the cylinder head with the secondary air injection valve Gas and exhaust gas to react, so that the three-way catalytic converter as soon as possible to achieve the working temperature, thus improving the warm-up process of emission performance. According to the working principle of the secondary air injection system, this tube should not be blown out of the air. There are two reasons for this phenomenon: the air pump switching valve (Y32) is always in the normally open state, the air pump switching valve (Y32) has been through the vacuum to open the secondary air injection valve; secondary air injection valve stuck, Open the state. Through the diagnostic device to observe the actual value of the air pump switch valve, has been in a closed state, and then through the diagnostic instrument to activate the open, close are normal, the exclusion is the air pump switch valve (Y32) problem. The following left the second air injection valve, and remove the secondary air injection valve and open and found the diaphragm was coke locked, can not be closed.

Since the secondary air injection valve can not be completely closed, the exhaust gas is returned to the intake pipe through the piping of the secondary air injection system so that the pressure of the intake manifold is increased and the exhaust gas is then introduced into the cylinder.

Because the entry of the exhaust gas, relatively fresh air will be reduced, so that fuel can not be fully burned, air-fuel ratio is not right, the engine jitter and reported mixed gas too thick fault. The secondary air injection valve carbon deposition clean, re-installed back, the engine running smoothly, the problem solved.

The next morning to wash the car ready to pick up the goods, start the vehicle and found the vehicle just off the car immediately, and then start the second time, start time is too long, but after the start of the engine running very smoothly. Then start a few times, everything is normal. Stopped a dozen minutes to start again, the failure appeared. And then use a multimeter to measure the starting voltage of 10V, normal. The low pressure of the fuel system is measured at about 500 kPa (standard value 400 to 670 kPa). Connect the diagnostic device, analyze the actual value of the engine at startup, found that the actual value of the downstream pressure sensor is not normal, its value is 38.6kPa
(Standard value is 20 ~ 40kPa), close to the critical value. Will be the second air pump inlet hose unplugged and found a blown air, turn off after ten minutes and then start the vehicle again, everything is normal. Again remove the secondary air injection valve and find that the diaphragm is jammed again. Remove the coke after careful observation, the diaphragm has been deformed, off lax, it is easy to be coke locked.

Replace the new secondary air injection valve after troubleshooting.

Fault summary
In the troubleshooting, we must comprehensively, CGDI MB Benz comprehensively and systematically consider, master the working principle of the engine system, according to the working principle of the possible parts of the failure to exclude one by one, careful analysis of the various failures and the actual value is very important Can help us find ideas and found that difficult to find the point of failure.

About Tacry J. Advanced   Auto Diagnostic Tool

4 connections, 0 recommendations, 102 honor points.
Joined APSense since, May 3rd, 2017, From WA, United States.

Created on Oct 18th 2017 20:37. Viewed 246 times.


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