What NOT To Do Within The Audi G28 Industry
What NOT To Do Within The Audi G28 Industry
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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 on the outside of the transmission over the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails to function, the ECU will display an error code P00160. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing can be a bit difficult because there are two connector pins and they perform different functions but the best method to test it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read about 1000 ohms. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs. Three were drenched in gazoline, the 4th one was dry. When I start the engine without sparks, I put a piece of tissue on top of each injector hole and the 3 that were drenched in gazoline leap out, however the 4th stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming the issue is in another place.
I also tried to reset PID but without success. The car can start when the G28 is not plugged in and is running fine when it is connected but it still has the intermittent misfire issue 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, whereas the actual pressure is 0.0 if i crank up the engine.
I don't know what to do. I get more info feel like i've pretty much eliminated everything else. I'm afraid i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter 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 salvage yard or in a local parts store. It is easy to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at here the connector's end audi a3 replacement key facing upwards). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines requires to know the position and speed of the crankshaft to determine timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could lead to an engine shut down.
A failing G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire while in the gear. If you have any of these problems, it is likely your sensor is failing and should be replaced. They're inexpensive and easy to locate especially if they're a Bosch unit like ours. Alternately, the GM version of this component is also a good option.
5. Tachometer
A damaged engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the transmission in your Audi, as it transmits information to the ECU regarding here how fast or slow the engine of the car is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to control fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should see an average resistance of 1000 ohms between these two points. more info This is a standard part that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.