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. The 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 in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control boost and fuel. 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 must know when the crankshaft reached TDC, and the location of the camshaft in order to activate the spark and injectors.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It can be a bit difficult to test as there are several connector pins, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when it is at full operation. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday accelerating full speed from highway paytoll, I experienced massive power loss as if the engine was running out of gas or injectors aren't firing at all. This morning i pull out the spark plugs, three were drenched with gazoline the fourth one was dry. I placed a tissue over each injector hole and when i turn the engine on without sparks, the ones with gazoline jump out. The 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I think the issue is elsewhere.
I also tried to reset the PID but without success. The car can start if the G28 is unplugged and is running fine when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value that is -49c even after unplugging it. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.
I don't know what to do. I feel like i've pretty much all other possibilities out. I'm concerned that i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. Test them out - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They should be infinite ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner which could cause engine shut down.
A damaged G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or a misfire in the gear. If you experience any of these issues, it is most likely that your sensor is failing and should be read more replaced. The good news is that they are very affordable and easy to find particularly when you're looking at an Bosch model, like ours. Alternately, GM's version this part would be an option.
5. Tachometer
A damaged engine sensor could cause a variety of issues in your car. It's a crucial component get more info of the transmission in your Audi, as it transmits information to the ECU about how fast or slow the car's engine is turning. When this sensor fails, it can affect the performance of the transmission as well as the other car's components.
The G5 engine sensor is located near the edge of the transmission, just above here the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, and also to timigrate. 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 the ECU pin T55/49 and the instrument cluster connection to pin here T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also more info find some good ones in wrecking yards.