20 Trailblazers Leading The Way In Audi G28
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 located near the edges of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors according to the situation.
If lost audi keys fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult as there are two different connector pins, and they serve different purposes 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 at full operation. If you're having issues with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had a big cut in power like the engine is out of gas or the injectors aren't firing at all. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth was dry. I put tissue over each injector hole, and when I turn the engine on without sparks, the three with gazoline jump out. The fourth one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero Ohm. I'm assuming that the issue is in another location.
I also tried to reset PID without success. The car is able to start when the G28 is not plugged in and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value 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 0.
I don't know what to do. I feel like i've pretty much eliminated everything else. I'm worried that i might have missed something. If anyone has any ideas 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 is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or parts store. It is simple to test them to do - just 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 end). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
A malfunctioning G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or an unfire when in gear. If you are experiencing any of these issues, it is likely your sensor is failing and needs replacing. They are cheap and easy-to-find especially in the case of an Bosch sensor like ours. If you prefer, GM's version of this component is an option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of issues with your vehicle. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how the car's crankshaft is spinning. If this sensor fails, it can cause problems for the transmission and the rest of the car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU uses this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can check for sensor 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 cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see approximately 1000 ohms of resistance between these two points. This is a standard part 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 might be availble in wrecking yards.