Case 1
The audi c7/a6l car cannot be activated while it's running
Fragmentation: audi c7/a6l vehicle 2. 5l engine, which cannot be activated while running。
Fault detection and analysis: first, engine oil level, normal. Trying to start the engine, it was found to be a little longer to start, but it was slow and unstoppable, accompanied by the sound of the engine. The failure code of the engine control unit is read with a diagnostic device, with a failure code p034100 - the g40 signal of the cam axis position is not credible. Check cam axis position sensor g40, line normal. A combination of the above-mentioned tests, the preliminary analysis is that the engine gas is out of order。
Fault clearance: after removal of the gas chamber covers, the shaking arm under the inflow cam of the first air tank cap was found to have broken, as shown in the figure. Further decomposition found that the fixed bolts of the remixable gas phase at the back end of the input cam were clearly loose and that the chain wheel was attached to the cam axis. The decomposition of the gas tank covers revealed that some of the gas doors and pistons were constricted and that the first tank covers were replaced to eliminate malfunctions。
Snack: what caused the first entry cam axis to die? Repeatedly examining the first air tank cap and finding that the first entry cam axis, the neck-walled oil hole, was blocked by sealed glue. The cam axle is lubricated from the corresponding oil hole on the cam axle by the main oil channel of the gas tank cover. The first axis of the entry cam was blocked by black seals, which led to a lack of lubrication and increased movement resistance. At this point, the axis leads to the forced rotation of the contour chain through a chain, which results in a loose chain bolt due to the reverse direction of the contour axis and the tight direction of the chain bolt. At this time, the gas phase is in disarray, causing interference with gas doors and pistons. The lesson of this case is that, when applying seals in combination, care must be taken whether there is an impact on the nearby oil lanes。
The shaking arm under the entry cam in the first column of the tank cap has broken
Case 2
The audi a6l car was cold when the engine was fast
Fragmentation: audi a6l, 2. 0tfsi engine, cold car without glitch。
Diagnosis and analysis of failure: the diagnostic instrument is used to read the failure code of the engine electrical control system, as follows:
04767 (p129f): unusual pressure on low pressure fuel systems。
12408 (p3078): anomalous performance in the control of the air-saving door position at a glitch。
Following examination of the air-saving door, which is dirty, cleans up the gas-saving door and uses the instrument for the basic design of the gas-saving door (060 passage), the engine is activated and the failure code of 04767 cannot be removed. Replacement of petrol filters, failure code still exists. The reading of data streams and observation of low pressure fuel pressure values for the first row of the data stream number, which remain constant at 1. 2 mpa, indicate that low pressure fuel pressure is high. Following the start-up of the engine, a high pressure fuel pressure of about 5 mpa at glitch speed was observed for the 106 group, with a sharp acceleration of up to 9-11 mpa, indicating normal pressure。
The audi a6l2. 0tfsi engine diagnostic system provides a better data flow analysis test for the fuel system. In the first row of data stream number 103, pressure values for low pressure fuel can be observed, which are monitored by low pressure fuel pressure sensors. In the first row of the data stream number 106, pressure values for high pressure fuel can be observed, with a fuel pressure of approximately 5 mpa at low speed and up to 11 mpa at high speed. This value is monitored by high pressure fuel pressure sensors on the distribution track. If a vehicle is unable to start, the failure of the fuel system is suspected and no fuel pressure sheet is required, a quick determination of the normality of the fuel pressure can be made, thus greatly increasing the efficiency of the failure determination。
Data stream number 103
1) actual fuel pressure (mbar) 3000 ~ 6000
2) controller fuel pressure (%mbar)
3) electric fuel pump match (%mbar)
4) fuel pump matching (testing cut off/chaming/matching normal/mistake)
Data stream number 106
1) fuel pipeline pressure (bar)
2) electric fuel pump 1/2 (cut/connect or pwm)
3) empty
4) breaking of time (s)
Fault clearance: replacement of low pressure fuel pressure sensor, spare parts no. 06e906051j. After replacement, clear the fail code, check the data flow, show normality, check the fail code, no fail code output。
Case 3
Odie a4l, failr signal alert
Fragmentation: the audi a4l car, 2. 0t engine, 0aw ungraded transformer, with a gear transformer sign alerting the central display screen of the device after the speed of more than 15 km/h has lasted several minutes。
Fault diagnosis and analysis: connection to the diagnostic machine, reading the failure code in the transmission control unit, with a failure code showing " no transmission from the speed transformer output transducer g195" and an occasional failure code. There are malfunctions in the reading engine control unit. The result of the failure guide of the transmission control unit was to check the transmission control unit and the output speed sensor to identify the disk (target wheel) and to begin to suspect that the failure should have been caused by the transmission control unit. The control unit was then removed and checked, both the sensor and the target wheel were normal, and an attempt was made to replace an identical configuration of the transformer control unit, to test the vehicle and the failure remained. The same failure code is kept in the control unit, and it is then normal to measure the input, output data of the transmission control unit against the configuration vehicle. The four-wheel speed measurements are normal. Attempting to replace the gear transformer, testing the car, still malfunctioning。
After various attempts, the cause of the failure remained undetectable, and the thinking was re-engineered, the failure code was removed, the diagnostic machine was tested, the need to see if the vehicle had any problems with engine and transmission data at the point of failure, all the data were normal before the malfunction occurred, the failure was inadvertently followed by a sudden deviation in engine speed, which could reach 7800 r/min, and the rest was normal, and the parking was followed by the removal of the g28 plug, the testing of the vehicle, the failure continued, the replacement of a new g28, the breakdown and repeated testing were normal。
Fault removal: replacement engine speed transducer g28, failure resolution。
Summary: the engine speed sensor g28 is only connected to the engine control unit, is not directly connected to the transmission control unit and is rarely thought of as a failure caused by the engine speed sensor。
Case 4
Tpms called the police while odie a4l was driving
Fragmentation: audi a4l (b8) car, cdz engine, cvt gearbox, tpms alert, esp alert。
Fault diagnosis and removal: the examination of the tires was normal and none of the four tyres had been nailed and no leaks were found. Linking diagnostics vas 5052, reading fault code, with "g41 - unreliability of transversal and accelerator sensor signals, occasional"。
The a4l foetal pressure monitoring system uses an indirect measurement system, which obtains the loss of tyre pressure through the esp's wheel-speed sensor and then transmits the cell pressure control module. In the case of a4l, the tyre pressure control module is integrated in the esp control unit, so that as long as the esp fails, the cell pressure control system will also alert the police。
First check the g419 signal for unreliability. In the course of the experiment, the mvb in the esp control module was read, and in data stream 5, the values of data 1 and data 3 and 4 were found to be the opposite. Data 1 is the g85 shift angle and data 3 and 4 is the g419 shift angle)。
In normal circumstances, direction will not change, and why not。
The failure was guided by vas 5052, which was initially marked as g85, and the test failure remained. It was determined that the dismantling of g419 had not taken place at the fixed position of g419 and that only one of the fixed bolts of the fixed g419 sensor had been left, the other had been broken and had been pasted with black glue. Checking the vehicle's configuration does not have esp, and therefore there is no turning angle sensor 2. G419 is installed in the direction angle sensor 2 after it is suspected that the vehicle has broken a fixed bolt during the plant assembly. After welding the fixed bolts, load g419 back in place and the test car failure disappears。
Fault removal: re-corrected installation to shift to swing rate and acceleration sensor g419, failure removal。
Synopsis: the shift to transverse and accelerator sensor g419 is directional and cannot be set up back when installed。
