Audi G28: 10 Things I'd Like To Have Learned In The Past
Audi G28: 10 Things I'd Like To Have Learned In The Past
Blog Article
How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.
If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging because there are two connector pins, and they perform different functions but the best method of testing it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. Examine for signs of coolant or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors are not firing at all. This morning i pull out the spark plugs. Three were drenched in gazoline, the fourth one was dry. When I start the engine without sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero ohm. I'm assuming the issue is in another place.
I also tried to reset the PID but without website success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even when unplugged, still shows a 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 if i crank up the engine.
I'm not certain what to do, as i believe that i've completely ruled out all other possibilities. I'm worried that i might have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. It is simple to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must be aware of the position and speed of the crankshaft to determine timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could lead to the engine shutting down.
A failing G28 sensor could cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or a misfire in gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these signs. The good news is they are very cheap and easily accessible, click here especially if you're looking at an Bosch sensor, like ours. Alternatively, GM's version of this component is an option.
5. Tachometer
A failing engine speed sensor could be a cause for numerous issues in your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor can cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed sensor is located on the edge of the transmission, here above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU uses this signal to control the amount of fuel and boost, and also timig. It also relays it to the G5 Tachometer in instrument cluster. You can test for more info sensor failure click here by examining the continuity of the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is a common part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.