The No. One Question That Everyone Working In Audi G28 Must Know How To Answer
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 at the edge of transmission, above the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer located 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 an electrical signal to ECU pin T55/49 via the grey wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.
If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).
It's a bit tricky to test as there are various connector pins, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is at full operation. Examine for signs of coolant, or oil in the connector bay if you have issues with this part.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a massive drop in power. It was as if the engine was running out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth was dry. When I crank the engine with no sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stay closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID but with no luck. The car can start when the G28 is not plugged in and it runs perfectly when it is connected but it still is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I don't know what to do. I believe that I've all other possibilities out. I'm afraid i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. Testing them is easy by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that needs to know the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will show codes that could cause the engine shutting down.
A malfunctioning G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or a misfire while in gear. If you experience any of these issues, it is likely that your sensor is deteriorating and needs replacing. The good news is they are very affordable and easily accessible, especially in the case of an Bosch model, which is what ours are. If you prefer, GM's version of this part would be a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of issues with your vehicle. It's an essential component of the transmission in your Audi since it sends information to the ECU on how fast or slow the car's engine is turning. When audi car keys fails, it will affect the performance of the transmission, as well as the rest of the car's components.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits a signal via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig, and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between the 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. There should be an average resistance of 1000 ohms in these areas. This is a common 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.