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 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 via the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU uses this information to control fuel and boost. It also sends an indicator to the G5 Tachometer within the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of 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 they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when it is at full operation. Check for evidence of coolant or oil in the connector bay if you have problems with this part.
2. new audi car key accelerating full speed from highway paytoll i had a big cut in power like the engine is out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. I put a piece of tissue over each hole in the injector and when i turn the engine on without sparks, the three with gazoline jump right out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. I assume that the problem is in another location.
I also tried to reset PID but without success. The car will start when the G28 is unplugged and it runs perfectly when it is connected, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I don't know what to do. I think I've ruled everything else out. I'm worried that i might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent 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. You can easily find a spare in a wrecking shop or parts store. It is simple to test them - simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). 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 position and speed of the crankshaft in order to make decisions regarding timing of the fuel injector, for example. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner which can lead to engine shutdown.
A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, or a misfire while in the gear. If you experience any of these problems, it is most likely that your sensor is going bad and requires replacement. The good thing is that they are very affordable and easily accessible, especially when you're looking at a Bosch sensor, which is what we have. Alternately, GM's version this part would be an option.
5. Tachometer
A damaged engine sensor could cause a number of problems in your car. It's a crucial component of the transmission in your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is turning. When this sensor fails, it can cause problems for the transmission as well as the rest of the car's components.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU uses this signal to regulate fuel and boost, as well as timig. It also transmits it to the G5 Tachometer located in the instrument cluster. You can test 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]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms of resistance between these two points. This is a standard part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.