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 at the top of the transmission above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper chain of timing. However the code will not 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 pins on the connector, 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 about 1000 ohms. If you are having problems with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is running out of gas or injectors are not firing any more. Today, i pulled out the spark plugs, three were soaked with gazoline and the fourth was dry. I put a piece of tissue over each hole in the injector and when I start the engine without sparks, the three with gazoline jump out. The fourth one remains closed. I tested the ground connection of ECU pins 14,30, check here and 48/55. I got zero ohm. Therefore, i think the issue is in another place.
I also tried to reset PID but without success. The car will start when the G28 is not plugged in and runs fine when it is connected but it still is experiencing intermittent misfires at higher RPM. The coolant get more info temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.
I don't know what to do. I believe that I've eliminated everything else. But i am afraid 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 signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender and more info both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. It is simple 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 read more upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft in order to make a decision about timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shut down.
A malfunctioning G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, and/or a misfire in the gear. If you are experiencing any of these problems, it is most likely that your sensor is deteriorating and requires replacement. The good news is they are very affordable and readily available particularly click here in the case of a Bosch unit like ours. Alternately, the GM version of this part is also a great option.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind a slew of issues in your car. It's an essential component of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. If the sensor fails, it will affect the performance of the transmission, as well as the other car's components.
The G5 engine speed sensor is located on the outside 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 uses this signal to regulate the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see approximately 1000 ohms of resistance between these two points. This is a common component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.