4 Dirty Little Secrets About Audi G28 Industry Audi G28 Industry
How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal the ECU via the grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, just above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to control the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in 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 code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two connector pins, and they serve different purposes however the best method to test it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is in full operation. If you're having issues with this part, check for evidence of oil or coolant in the connector bay.
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 the injectors are not firing any more. This morning i pull out the spark plugs. Three were soaked with gazoline and the 4th one was dry. When I start the engine without sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th stay shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID but with no luck. The car can start if the G28 is disconnected and it runs perfectly when it is connected but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not certain what to do, i believe that i've completely ruled out all other possibilities. However, i'm afraid that I may have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal by 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 the spare in a salvage shop or a parts store. Testing them is easy by putting your DMM in resistance mode and take measurements 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 have an ECU that has to know the position and speed of the crankshaft to make a decision about fuel injector timing etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these, the diagnostic scanner will show codes that could lead to an engine shutdown.
Some of the symptoms of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or misfiring when you're in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. The good thing is that they are very affordable and readily available particularly in the case of an Bosch sensor, like ours. Alternately, GM's version this part would be a good option.
5. Tachometer
A malfunctioning engine sensor can cause a myriad of issues in your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU on how fast or slowly the engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine speed sensor is located on the outside of the transmission just above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU uses this signal to regulate fuel and boost, and also to timigrate. G28 Car Keys UK relays it to the G5 Tachometer located in 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 [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is a standard component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.