7 Small Changes That Will Make An Enormous Difference To Your Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is situated near the edges of the transmission above the flywheel ring gear. It sends a message to the ECU through a 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, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends a signal to the G5 tachometer inside 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 accordingly.
If this sensor fails to function, the ECU will display a P00160 error code. 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 jumpy chain link in the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing can be a bit difficult since there are two connector pins, and they serve different purposes but the most effective method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline leap out, however the 4th stay shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. Therefore, i think the issue is somewhere else.
I also tried to reset the PID but with no luck. audi replacement keys is able to start if the G28 is unplugged and it runs perfectly when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not sure what to do, but i feel i have pretty much ruled out everything else. I'm afraid i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is simple to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner which could cause engine shut down.
Some of the signs of a failing G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when in gear. If you are experiencing any of these problems, it is likely your sensor is failing and should be replaced. They're cheap and easy to find particularly in the case of a Bosch sensor like ours. If you prefer, GM's version of this part would be an excellent choice.
5. Tachometer
A faulty engine speed sensor could be a cause for numerous issues in your car. It's an essential component of the transmission of your Audi, as it transmits information to the ECU on how fast or slow the engine is turning. This sensor could cause the transmission to fail and other components in the car to be affected.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those points. This is a common component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.