10 Things You've Learned In Preschool, That'll Aid You In Audi G28

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. The sensor is located at the edge of transmission over the flywheel gear. It transmits a signal to the ECU through an uncolored 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 G28 Engine Speed Sensor sends signals to ECU pin T55/49 via a grey wire. The ECU uses this information to control fuel and boost. It also sends signals to the G5 Tachometer located in 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 position of the camshaft, to trigger the spark and injectors.

If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jump in the chain link of the upper chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging as there are two different connector pins and they perform different functions but the most effective method to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is in full operation. If you are having problems with this sensor, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the 4th one was dry. I put a piece of tissue over each injector hole and when I start the engine without sparks, the 3 that have gazoline pop right out. The 4th one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I'm assuming the issue is in another place.

I also tried to reset the PID without success. The car will start when the G28 is disconnected and is running fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.

G28CarKeys 'm not sure what to do, as i believe that i've eliminated everything else. I'm worried that i might have missed something. If anyone has suggestions, please let me know! TIA!


3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. Test them out to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions about timing of the fuel injector, for example. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go badly, you will see codes on the diagnostic scanner which can cause the engine to shut down.

A damaged G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or an unfire when in the gear. It is probable that the sensor is failing and needs to be replaced if you experience any of these signs. The good news is that they are quite affordable and easily accessible, especially in the case of an Bosch unit which is what we have. You can also choose the GM version of this unit is also a good choice.

5. Tachometer

A damaged engine sensor could cause a variety of issues in your car. It's an essential component of the transmission of your Audi because it relays information to the ECU on how fast or slow the engine of the car is spinning. If the sensor fails, it can affect the performance of the transmission as well as the rest of the car's components.

The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and processes the signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test the sensor for failure by examining the 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 [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU So, you may find good ones in wrecking yards.

Edit Report
Pub: 29 Sep 2024 17:23 UTC
Views: 28