What Do You Think? Heck What Exactly Is Audi G28?
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission just 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 sensor is located at the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using a grey wire. thekeylab.co.uk utilizes this information to control fuel and boost. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two pins for the connector and they have different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading around 1000 ohms. If you're experiencing issues with this sensor, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is out of gas or the injectors are not firing any more. In the morning, i removed the spark plugs, three were drenched with gazoline the 4th one was dry. When i crank the engine with no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stay closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is elsewhere.
I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I believe that I've all other possibilities out. However, i'm afraid that I might have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. It is simple to test them 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 must 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 to make a decision about fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will show codes that could lead to the engine shutting down.
Some of the signs of a failed G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you have any of these problems, it is likely your sensor is deteriorating and needs replacing. The good news is they are very cheap and easily accessible, especially when you're looking at the Bosch unit like ours. Alternately, the GM version of this component is also a good option.
5. Tachometer
A damaged engine sensor could cause a number of problems in your car. It's a crucial component of the transmission of your Audi because it relays information to the ECU about how fast or slow the engine of the car is spinning. When this sensor fails, it can affect 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 via a grey wire. The ECU then uses and processes the signal to control fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU So, you may find some good ones in wrecking yards.