4 Dirty Little Secrets About Audi G28 And The Audi G28 Industry
4 Dirty Little Secrets About Audi G28 And The Audi G28 Industry
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How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via a grey wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, just above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC, and the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails, the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper timing chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test as there are various connector pins, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should read approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs, three were soaked with gazoline and the 4th one was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 that were drenched in gazoline jump out but the 4th stay shut. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. I assume that the problem is in another location.
I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of get more info that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.
I'm not sure what to do, as i think i've pretty much ruled out everything else. But i am afraid I may have missed something. If anyone spare audi key has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is simple to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines needs to know the position and speed of the crankshaft to determine timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger the engine shutting down.
A failing G28 sensor could result in an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, or a misfire in gear. It is possible that the sensor is failing and needs to be replaced if you encounter any of these signs. They're inexpensive and easy to locate, especially in the case of an Bosch unit like ours. Alternatively, the GM version of this part is also a great option.
5. Tachometer
A failing engine sensor could cause a myriad more info of issues in your car. It is a crucial part of the Audi's transmission as it sends information to the ECU about how the car's crankshaft is rotating. If this sensor fails, it could cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig, and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You read more can check the sensor for any failure by checking the continuity between it and the audi a1 keys tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is a typical part that is found across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.