The Most Worst Nightmare About Audi G28 It's Coming To Life
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 situated near the transmission's edge just above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 via the grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two pins for the connector and they serve different purposes but the most effective way to test it is to measure resistance between the sensor and the ECU. When the sensor is fully functional, it should read about 1000 ohms. Look for signs of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs. Three were soaked with gazoline and the fourth one was dry. When audi key replacement start the engine with no sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th stay shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I assume that the problem is elsewhere.
I also tried to reset the PID with no success. The car can start when the G28 is not plugged in and runs fine when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I'm not sure what to do. I believe that I've eliminated everything else. I'm afraid i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. It is simple to test them by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They should 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 to make decisions regarding fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire while in the gear. If you experience any of these problems, it is likely your sensor is deteriorating and requires replacement. The good thing is that they are quite affordable and easy to find particularly when you're looking at an Bosch unit like ours. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A faulty engine speed sensor could be the cause of numerous issues with your vehicle. It is a crucial part of the Audi's transmission as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. When this sensor fails, it could cause problems for the transmission as well as the other car's components.
The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to regulate the amount of fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms of resistance between those two pins. This is a common component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.