7 Little Changes That'll Make A Big Difference In Your Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located near the edges of the transmission above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through the grey wire. The ECU uses this information to control fuel and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC and also where the camshaft lies in order to activate the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error code. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are various pins on the connector and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a significant decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning, three were soaked with gasoline and the 4th was dry. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one remains closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero Ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID but without success. The car can start if the G28 is disconnected and it runs perfectly when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.
I'm not sure what to do, as i think i've pretty much eliminated everything else. I'm afraid i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or at a parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injector, for example. It uses 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 the codes that could trigger an engine shutdown.
The signs of a failed G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or misfiring when in gear. g28carkeys.co.uk is likely that your sensor is failing and requires to be replaced if you encounter any of these signs. They are cheap and easy-to-find especially if they're a Bosch sensor like ours. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of issues in your car. It's a vital component of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is turning. When this sensor fails, it will disrupt the performance of the transmission as well as the rest of the car's components.
The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU uses this signal to regulate the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer in instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find good ones in wrecking yards.