"The Ultimate Cheat Sheet" On Audi G28
How to Replace an audi A3 spare replacement key audi; images.google.is, G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It transmits a signal the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using an uncolored wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors accordingly.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).
It's a bit tricky to test as there are different connector pins, and each one has different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. If the sensor is functional, it should read approximately 1000 ohms. Look for signs of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. I placed a tissue over each injector hole and when I turn the engine on without sparks, the 3 with gazoline jump out. The 4th one remains closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming that the issue is in another location.
I also tried to reset PID but without success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when it is unplugged, shows a temperature of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 if i crank up the engine.
I don't know what to do. I believe that I've eliminated everything else. I'm worried that i might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style sender is the same as the G4 and they both work in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. It is simple to test them by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). 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. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either one of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.
Some of the signs of a failed G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when you're in gear. If you experience any of these problems, it is most likely that your sensor is failing and should be replaced. They are cheap and easy-to-find particularly when they're an Bosch sensor like ours. Alternatively, GM's version of this part would be a good option.
5. Tachometer
A damaged engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission of your audi tt key programming since it sends information to the ECU on how fast or slowly the engine of the car is turning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a standard part that is found across the audi etron key 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.
