The Three Greatest Moments In Audi G28 History
How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge over the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. replacement key audi TheKeyLab uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and where the camshaft lies to trigger the spark and injectors.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).
It is a little tricky to test because there are various 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. When the sensor is operational, it should be reading about 1000 ohms. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced a big cut in power like the engine is running out of gas or the injectors aren't firing anymore. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th one stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. So i assume the problem is elsewhere.
I also tried to reset the PID without success. The car is able to start when the G28 is disconnected and it runs perfectly when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is zero.
I'm not sure what to do, but i believe that i've ruled out everything else. But i am afraid I might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from 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 has to know the position and speed of the crankshaft in order to make decisions about timing of the fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these sensors, the diagnostic scanner will display codes that could cause an engine shut down.
A failing G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or an unfire when in gear. It is probable that your sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is they are very cheap and readily available particularly in the case of an Bosch model, which is what ours are. Alternately, the GM version of this component is also a good option.
5. Tachometer
A failing engine speed sensor could be a cause for many problems in your vehicle. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the car's engine is turning. When this sensor fails, it can disrupt the performance of the transmission, as well as the rest of the car's components.
The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to control fuel and boost, and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This is a typical part across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.
