Why Audi G28 Isn't A Topic That People Are Interested In.
Why Audi G28 Isn't A Topic That People Are Interested In.
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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 situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The 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 connect the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and the position of the camshaft, in order to 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 out of line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumped chain link in the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are various connector pins, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is functional, it should read about 1000 ohms. If you're experiencing issues with this sensor, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or my injectors weren't firing. Today, i pulled out the spark plugs. Three were drenched in gazoline, the 4th one was dry. When i crank the engine, there are no sparks i put tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stay shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is elsewhere.
I also tried to reset PID without success. The car will start if the G28 is unplugged and it runs perfectly when it is connected however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows check here an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, i feel i have pretty much ruled out everything else. But i am afraid I may have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage click here shop or parts store. Test them out - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and click here ADU) engines have an ECU that has to know the speed and position of the crankshaft in order to make read more decisions about fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down.
Some of the symptoms of a malfunctioning G28 sensor are here an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when in gear. If you have any of these problems, it is most likely that your sensor is going bad and should be replaced. The good thing is that they are very cheap and easily accessible particularly if you're looking at an Bosch model, which is what ours are. Alternately, GM's version this part would be a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues in your vehicle. It's an essential component of the transmission of your Audi since it sends information to the ECU on how fast or slowly the car's engine is turning. When this sensor fails, it could cause problems for the transmission and the rest of the car's components.
The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to control the flow of fuel and boost and also timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see an average resistance of 1000 ohms between these points. 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.