The 3 Biggest Disasters In Audi G28 History
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft 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 a P00160 error message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumped chain link in the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).
It is a little tricky to test as there are several pins on the connector, and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is in full operation. Examine for evidence of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at a high speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs. Three were drenched with gazoline the 4th one was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each of the injector holes, the 3 drenched with gazoline jump out but the 4th stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. I assume that the problem is elsewhere.
I also tried to reset the PID with no success. The car is able to start if the G28 is disconnected and is running fine when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do. I feel like i've pretty much ruled everything else out. However, i'm afraid that I may have missed something. If anyone has any suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor 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 from a parts store. It is easy to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.
Some of the symptoms of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. It is probable that your sensor is failing and requires to be replaced if you notice any of these symptoms. The good news is they are quite affordable and easily accessible, especially in the case of a Bosch sensor, which is what ours are. Alternately, GM' audi a1 key is a good option.
5. Tachometer
A damaged engine sensor could cause a myriad of issues in your car. It is an important part of the transmission in your Audi, as it transmits information to the ECU on how fast or slowly the engine is turning. If the sensor fails, it will disrupt the performance of the transmission and the other car's components.
The G5 engine speed sensor is located at the outside of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes this signal to regulate the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Additionally, you can 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 and pin T26a/12. You should see approximately 1000 ohms resistance between those points. This is a common feature across the Audi 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.