How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge over the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to control fuel and boost. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors accordingly.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumped chain link in the upper chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit tricky since there are two pins for the connector and they have different functions but the best method of testing it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is in full operation. Check for evidence of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a significant drop in power. It was like the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth was dry. When I crank the engine without sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline pop out, but the 4th one stays closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I get 0ohm. I'm assuming the issue is somewhere else.
I also tried to reset PID but without success. The car is able to start when the G28 is disconnected and it runs perfectly when it is connected however it has intermittent misfire issues at website higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, but i believe that i've ruled out everything else. I'm concerned that i may have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the speed and position of the crankshaft in order to make a decision about timing of fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, 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 your gearbox or a gearbox that shifts more quickly than normal, and/or an unfire when in gear. If you have any of these problems, it is likely that your sensor is deteriorating and should be replaced. The good news is they are quite affordable and easy to find, especially in the case of an Bosch sensor, which is what ours are. If you prefer, GM's version of this part would be a good option.
5. Tachometer
A failing engine sensor could cause a variety of issues in your vehicle. It's a vital component of your Audi's transmission, because read more it communicates to the ECU about how the car's crankshaft is rotating. If the sensor fails, it could disrupt the performance of the transmission and the other car's components.
The G5 engine sensor is located website near the edge of the transmission, over the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can test for get more info sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This is a typical part across the Audi 80 100 200, UrS and RS2 read more range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.