10 Wrong Answers To Common Audi G28 Questions: Do You Know The Right Ones?
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located at the edge of transmission, above the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) and then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through the grey wire. The ECU uses this information to regulate fuel and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can start spark and injectors accordingly.
If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped 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's a bit tricky to test since there are various pins on the connector, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is operating at its maximum. Look for signs of coolant or oil in the connector bay if there are issues with this part.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed, i noticed a huge drop in power. It was like the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was unclean. When i crank the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stay closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero ohm. I'm assuming the issue is in another place.
I also tried to reset the PID without success. The car is able to start when the G28 is not plugged in and runs fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. I also 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 don't know what to do. I think I've all other possibilities out. However, i'm afraid that I may have missed something. If advanced key audi has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style sender is identical to the G4 and both function in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is simple to test them - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either one of these, the diagnostic scanner will show codes that could cause the engine shutting down.
A failing G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, and/or a misfire while in the gear. If you experience any of these issues, it is likely your sensor is failing and needs replacing. The good news is they are quite affordable and readily available particularly in the case of an Bosch model, like ours. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of issues in your vehicle. It's an essential component of the transmission of your Audi, as it transmits information to the ECU on how fast or slowly the engine is spinning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It transmits signals via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer located in 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 to pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. 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 so good ones could be available in wrecking yards.