Audi G28 10 Things I Wish I'd Known In The Past
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 at the top of the transmission above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using an uncolored wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors according to the situation.
If this sensor fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumpy chain link in the upper timing 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 have different functions however the best way to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. If you're having issues with this sensor, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were drenched with gazoline the fourth one was dry. When i crank the engine with no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th one stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I assume that the problem is somewhere else.
I also tried to reset PID without success. The car is able to start when the G28 is unplugged and is running fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not certain what to do, as i think i've pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter functions similarly 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 simple to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines needs to know both the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes bad you will get codes on the diagnostic scanner which can lead to engine shutdown.
Some of the symptoms of a failed G28 sensor are an inaccurate rev counter in the gearbox and gears that shift faster than normal, and/or a misfire when you are in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find especially in the case of a Bosch sensor like ours. Alternatively, GM's version of this part would be an option.
5. Tachometer
A faulty engine speed sensor could be the cause of a slew of problems in your car. lost audi key 's a crucial component of the transmission of your Audi because it relays information to the ECU on how fast or slow the car's engine is turning. This sensor could cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then processes this signal to control the flow of fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. There should be a resistance of approximately 1000 ohms between these 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 could be available in wrecking yards.