Audi G28 10 Things I'd Like To Have Learned In The Past
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge over the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).
It can be a bit difficult to test because there are several pins on the connector, and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should read approximately 1000 ohms. Look for signs of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced a big cut in power like the engine is running out of gas or injectors are not firing at all. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. I placed a tissue over each injector hole and when I turn the engine on without sparks, the 3 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. So i assume the problem is in another place.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.
I'm not sure what to do, as i believe that i've eliminated everything else. I'm afraid i may have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. Testing them is easy - 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 end). replacement key for audi a3 must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the position and speed of the crankshaft to make decisions about fuel injector timing etc. To do this, it makes use of 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 could cause engine shut down.
A malfunctioning G28 sensor could result in an inaccurate speed counter for your gearbox or a gearbox that shifts more quickly than normal, or a misfire in gear. If you experience any of these issues, it is likely your sensor is going bad and requires replacement. 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 malfunctioning engine speed sensor could be the cause of a slew of problems in your car. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. If the sensor fails, it will cause problems for the transmission and the rest of the car's components.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends a signal via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those two pins. This is a common 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 might be availble in wrecking yards.