The Reason You Shouldn't Think About Enhancing Your Audi G28 > 자유게시판

How to Replace an audi replacement key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission over the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors in the right way.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).

It can be a bit difficult to test because there are several pins on the connector and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Examine for audikey [Technetbloggers link for more info] signs of coolant, or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday accelerating full speed from highway paytoll, I experienced massive power loss as if the engine was running out of gas or the injectors are not firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was unclean. I put a piece of tissue over each hole in the injector and when i start the engine without sparks, the ones that have gazoline pop right out. The 4th one 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 elsewhere.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The coolant sensor (G62), even when it is unplugged, shows a temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, but i think i've pretty much ruled out everything else. I'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to 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 wrecking yard or from a parts store. It is simple to test them - just put your DMM into resistance mode and test 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 in our 20vt turbo (3B AAN ABY ADU) engines requires to know both the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.

Some of the symptoms of a failing G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when in gear. If you experience any of these issues, it is likely your sensor is failing and requires replacement. They are cheap and easy-to-find particularly if they're a Bosch sensor like ours. If you prefer, GM's version of this part would be an option.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of numerous issues in your vehicle. It's an essential component of the audi new key's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it could cause problems for the transmission as well as the other car's components.

The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through an uncolored wire. The ECU is then able to process the signal to control the flow of fuel, timig and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, 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. You should see the resistance to be around 1000 ohms between these points. This is the same across the audi replacement key service 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU, so you might find them in wrecking yards.