10 Times You'll Have To Learn About Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission just above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer within 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 signals 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 indicator to the G5 Tachometer in instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and could indicate the chain is stretched or a jump link on the upper timing chain. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins and they perform different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is operating at its maximum. If you're experiencing issues with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge drop in power. It was as if the engine had run out of gas. Or my injectors weren't firing. Today, i pulled 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 start the engine with no sparks, the three with gazoline jump right out. The fourth one remains closed. 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 without success. The car is able to start if the G28 is unplugged and is running fine when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (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, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, i believe that i've completely ruled out all other possibilities. But audi replacement key service near me am afraid I might have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent 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 find a spare in a wrecking shop or a parts store. It is simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They should be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display codes that could lead to an engine shut down.
A damaged G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or an unfire when in the gear. If you are experiencing any of these issues it is most likely that your sensor is going bad and requires replacement. The good thing is that they are quite affordable and easily accessible particularly in the case of the Bosch model, which is what ours are. Alternately, GM's version this part would be an option.
5. Tachometer
A failing engine speed sensor could be the cause of numerous problems in your vehicle. It's a vital component of your Audi's transmission, because it communicates to the ECU about how fast or slow the car's crankshaft is turning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU is then able to process this signal to regulate fuel, timig, and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe around 1000 ohms of resistance between those points. This is a standard component across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.