How To Beat Your Boss Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer within the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the location of the camshaft in order to activate the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two pins for the connector and they serve different purposes but the most effective method of testing it is to measure resistance between the sensor and the ECU. When the sensor is fully functional, it should read around 1000 ohms. Check for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth was dry. When I start the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th one stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. More Help get 0ohm. So i assume the problem is in another place.
I also tried to reset the PID without success. The car is able to start when the G28 is not plugged in and it runs perfectly when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I believe that I've eliminated everything else. But i'm worried that I may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. It is easy to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must know the position and speed of the crankshaft to determine fuel injector timing, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will display codes that could cause an engine shut down.
The signs of a malfunctioning G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you are experiencing any of these issues it is likely that your sensor is deteriorating and needs replacing. The good thing is that they are quite affordable and readily available particularly in the case of a Bosch model, which is what ours are. Alternately, the GM version of this unit is also a great option.
5. Tachometer
A failing engine speed sensor could be the cause of numerous problems in your vehicle. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how the car's crankshaft is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU uses this signal to control the amount of fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du So, you may find good ones in wrecking yards.