Three Greatest Moments In Audi G28 History
From Shiapedia
How to Replace an audi tt key fob 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, above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) and then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC, and the location of the camshaft to trigger the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test because there are various connector pins, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is operational, it should be reading approximately 1000 ohms. If you're experiencing issues with this component, look for signs of coolant or oil in the connector Spare bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is out of gas or the injectors aren't firing at all. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. I put a piece of tissue over each hole in the injector and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one remains closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero ohm. Therefore, i think the issue is somewhere else.
I also tried to reset the PID without success. The car will start if the G28 is unplugged and is running fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, as i feel i have pretty much eliminated everything else. However, i'm afraid that I might have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or a parts store. It is simple to test them - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They should be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, or a misfire while in gear. It is possible that your sensor is failing and needs to be replaced if you encounter any of these symptoms. The good news is that they are very affordable and easy to find, especially in the case of a Bosch model, like ours. Alternatively, the GM version of this component is also a good option.
5. Tachometer
A failing engine sensor could cause a myriad of issues in your vehicle. It's an essential component of your audi key programmer's transmission, as it sends information to the ECU about how the car's crankshaft is spinning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU is then able to process this signal to control the flow of fuel, timig and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a typical part that is found across the audi tt key case 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.
