This Week's Most Popular Stories About Audi G28
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 located at the edge of transmission just above the flywheel gear. It sends 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
Located on the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through an uncolored wire. audi car keys replacement utilizes this information to regulate boost and fuel. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails when it fails, 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 be a sign of a chain stretch or a jumped chain link in the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are different pins on the connector, and each has its own functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading approximately 1000 ohms. If you're having issues with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive reduction in power. It was like 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 unclean. When I crank the engine, there are no sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline leap out, however the 4th one stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero Ohm. I think the issue is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.
I'm not sure what to do. I believe that I've eliminated everything else. I'm concerned that i may have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is simple to test them to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They must be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will display codes that could cause an engine shut down.
Some of the symptoms of a failing G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when you are in gear. If you experience any of these problems, it is likely that your sensor is failing and needs replacing. The good news is they are very cheap and easy to find, especially in the case of an Bosch unit like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A failing engine sensor could cause a variety of issues in your vehicle. It is a crucial part of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is rotating. If this sensor fails, it can affect the performance of the transmission, as well as the rest of the car's components.
The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU then processes this signal to control fuel, timig and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can examine the continuity between pins 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 approximately 1000 ohms of resistance between these two points. This is the same 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, so you might find them in wrecking yards.