You Will Meet You The Steve Jobs Of The Audi G28 Industry
How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.
If this sensor fails, the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain is stretched or a jump 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 is a little tricky to test because there are different pins on the connector and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. If you're having issues with this part, check 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 significant reduction in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth one was dry. When I start the engine without sparks i put tissue on the top of each hole in the injector and the 3 that were drenched in gazoline jump out but the 4th stay closed. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero ohm. I assume that the problem is in another location.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a 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 all other possibilities out. I'm concerned that i may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you are in gear. It is probable that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is that they are quite affordable and readily available, especially when you're looking at a Bosch unit which is what ours are. Alternatively, the GM version of this unit is also a good option.
5. Tachometer
A failing engine sensor could cause a number of problems within your vehicle. It is an important part of the transmission in your Audi because it relays information to the ECU regarding how fast or slowly the car's engine is turning. If the sensor fails, it could cause problems for the transmission and the other car's components.
The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via a grey wire. car key cover audi uses and processes this signal to regulate fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms in these areas. This is a standard component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.