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. The sensor is located at the edge of transmission over the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control boost and fuel. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper timing chain. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky since there are two connector pins, and they serve different purposes but the best method to test it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a significant drop in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. When I crank the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th stay closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, i feel i have pretty much eliminated everything else. I'm concerned that i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal by the RPM sensor. check here The GM-style transmitter is the same as 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 junkyard or at a parts store. It is simple to test them to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed of the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go badly, you will see codes on here the diagnostic scanner check here that can cause the engine to shut down.
The signs of a failed G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or misfiring when you are in audi spare key gear. If you experience any of these issues, it is likely that your sensor is deteriorating and should be replaced. They're inexpensive and easy to locate especially in the case of an Bosch unit like ours. Alternately, GM's version this part would be an option.
5. Tachometer
A faulty engine speed sensor could be a cause for numerous problems 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 the vehicle's crankshaft is spinning. This sensor can cause the replacement audi car key transmission to fail and other car components to be affected.
The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the flow of fuel and boost as well as timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. You can also check continuity between pin 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 see around 1000 ohms of resistance between those two pins. This is a standard component across the Audi 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.