7 Simple Changes That'll Make A Big Difference In Your Audi G28
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 located near the edges of the transmission just above the flywheel ring gear. It sends 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 situated on the edge of transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends an indication 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 is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging as there are two different connector pins, and they serve different purposes but the best method to test it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is in full operation. Examine for signs of coolant, or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power like the engine is running out of gas or the injectors are not firing at all. I pulled out the spark plugs this morning, three were soaked with gasoline and the fourth was dry. I placed a tissue over each injector hole, and when i start the engine with no sparks, the three with gazoline jump out. The fourth one remains shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. 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 plugged in but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not sure what to do. I think I've eliminated everything else. However, i'm afraid that i might have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both function in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. It is simple to test them to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's side). They must be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must know both the position and speed of the crankshaft to make decisions regarding timing of fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.
A failing G28 sensor could cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. It is possible that your sensor is failing and needs to be replaced if you notice any of these signs. They're inexpensive and easy to locate especially when they're an Bosch model like ours. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to malfunction and other car components to be affected.
The G5 engine speed sensor is located on the edge 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 then uses and processes the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, 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 observe approximately 1000 ohms of resistance between these two points. audi key fob is the same across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 DU You may also find some good ones in wrecking yards.