What Is The Heck What Exactly Is Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission just above the flywheel gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the location of the camshaft in order to activate the spark and injectors.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are several pins on the connector, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. If audi replacement key is operational, it should read approximately 1000 ohms. If you are having problems with this part, check for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll i had massive power loss like the engine is out of gas or the injectors aren't firing anymore. In the morning, i removed the spark plugs. Three were drenched with gazoline the fourth was dry. I put tissue over each injector hole and when i start the engine with no sparks, the three that have gazoline pop right out. The fourth one remains closed. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero Ohm. I'm assuming the issue is in another place.
I also tried to reset the PID but without success. The car is able to start when the G28 is unplugged and it runs perfectly when it is connected but it still is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c, even if I unplug it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, but i think i've pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. Test them out 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 the left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft to make decisions 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 are experiencing issues with either one of these, the diagnostic scanner will display codes that could cause an engine shut down.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you are experiencing any of these problems, it is likely that your sensor is deteriorating and should be replaced. The good news is that they are quite affordable and easily accessible, especially if you're looking at a Bosch model, which is what ours are. Alternately, the GM version of this component is also a great option.
5. Tachometer
A failing engine speed sensor could be a cause for many problems in your vehicle. It is an important part of the transmission of your Audi since it sends information to the ECU about how fast or slowly the engine of the car is spinning. If this sensor fails, it could affect the performance of the transmission as well as the other car's components.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends 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 inside 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 see a resistance of approximately 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU, so you might find them in wrecking yards.