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 situated on the outside of the transmission, above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, just above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC and also where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit challenging because there are two pins for the connector and they serve different purposes however the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is functional, it should read approximately 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. When I crank the engine without sparks i put tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th stays closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID without success. The car will start if the G28 is disconnected and is running fine when it is plugged in, but still has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c even when i unplug it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I think I've eliminated everything else. I'm concerned that i may have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the check here RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. It is easy to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed of the crankshaft to determine timing of the fuel injector, etc. In order to website do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter get more info a problem with either of these sensors, the diagnostic scanner will show codes that could cause an engine shutdown.
The signs of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when you're in gear. It is probable that your sensor is failing and needs to be replaced if you notice any of these signs. The good thing is that they are replacement audi key very cheap and easily accessible particularly in the case of the Bosch unit which is what ours are. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A failing engine speed sensor could be the cause of a slew of issues in your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slow check here the engine of the car is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then processes this signal to regulate fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU You may also find them in wrecking yards.