Audi G28: The Good, The Bad, And The Ugly
Audi G28: The Good, The Bad, And The Ugly
Blog Article
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 situated at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging since there are two pins for the connector and they perform different functions however the best method to test it is to measure the resistance between the sensor and the ECU. When the sensor is functional, it should read around 1000 ohms. If you are having problems with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power as if the engine was running out of gas or injectors aren't firing any more. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the 4th was dry. I put tissue over each hole in the injector and when I start the engine without sparks, the ones with gazoline jump right out. The fourth one remains closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found 0ohm. I assume that the problem is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even here after unplugging it. 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, i believe that i've completely ruled out all other possibilities. But i am afraid I may have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sender is the same as the G4 and both are used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or in a local parts store. It is easy to test them - simply switch 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 must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.
A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or an unfire when in the gear. It is possible that website the sensor is failing and needs to be replaced if you notice any of these signs. The good news is that they are very affordable and readily available, especially if you're looking at the Bosch sensor, which is what we have. If you prefer, GM's version of this part is an excellent choice.
5. Tachometer
A failing engine speed sensor could be a cause for numerous issues in your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow new audi car key the car's crankshaft is turning. When this sensor fails, it will cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. Also, you here can 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 as well as pin T26a/12. You should observe approximately 1000 ohms resistance between those points. audi replacement keys This is a standard component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.