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. This sensor is located near the transmission's edge just above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test because there are several pins on the connector and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is fully functional, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if there are issues with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is out of gas or injectors are not firing any more. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. I placed a 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 checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I think the issue is elsewhere.
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 issue still occurs at higher RPM. The coolant temperature sensor (G62) shows the wrong more info temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I don't know what to do. I believe that I've eliminated everything else. But i am afraid I might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local 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 on the connector's edge facing up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will display codes that could cause an engine shut down.
The signs of a malfunctioning G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when in gear. If you are experiencing any of these issues, it is most likely that your sensor is failing and requires replacement. The good news is they are very affordable and readily available particularly when you're looking at an Bosch sensor, which is what ours are. Alternatively, the GM version of this read more part is also a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of issues with your car. It's a vital component of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is spinning. If the sensor fails, it can cause problems for 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 then uses and processes this signal to regulate check here fuel, timig and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument read more cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should observe approximately here 1000 ohms resistance between those points. This is a standard part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.