10 Tips For Getting The Most Value From Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, directly above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. spare audi key utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used 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 so it can start spark and injectors in the right way.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging since there are two connector pins, and they perform different functions however the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should be reading around 1000 ohms. Check for signs of coolant, or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum 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. Today, i pulled out the spark plugs, 3 were drenched in gazoline, the fourth one was dry. I put a piece of tissue over each injector hole, and when i start the engine with no sparks, the three with gazoline jump out. The 4th one remains closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.
I also tried to reset the PID but without success. The car will start if the G28 is not plugged in and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do, i feel i have pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work 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 easy to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). 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 timing of the fuel injector, for example. 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 of these sensors, the diagnostic scanner will display codes that could cause an engine shutdown.
A damaged G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, and/or a misfire while in the gear. It is likely that your sensor is failing and needs to be replaced if you encounter any of these signs. They are cheap and easy-to-find especially when they're a Bosch model like ours. Alternately, GM's version this part is a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind numerous issues in your car. It's an essential component of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU is then able to process the signal to control fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [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 part that is found 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.