10 Things You Learned In Preschool, That'll Aid You In 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. The sensor is situated at the top of the transmission above the flywheel ring gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If audi spare key fails to function, the ECU will display an error code P00160. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test because there are various pins on the connector and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is in full operation. If you are having problems with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is out of gas or injectors aren't firing at all. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. When I crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. So i assume the problem is in another place.
I also tried to reset PID without success. The car can start when the G28 is disconnected and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. Also, i 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. I believe that I've ruled everything else out. But i am afraid i might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to 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 - 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 left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to know the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. To do this, it uses 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 codes that could cause an engine shutdown.
The signs of a failed G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal, and/or a misfire when in gear. It is possible that the sensor is failing and needs to be replaced if you experience any of these signs. They're inexpensive and easy to locate especially when they're an Bosch model like ours. Alternately, the GM version of this part is also a good choice.
5. Tachometer
A faulty engine speed sensor could be the cause of numerous problems in your car. 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 is spinning. If the 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. It transmits a signal to the ECU at pin T55/49 through a grey wire. The ECU then uses and processes the signal to control fuel, timig, and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms between these points. This is a standard part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.