This Is The Ugly The Truth About Audi G28
This Is The Ugly The Truth About Audi G28
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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 located at the edge of transmission just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via a grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors in the right way.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging because there are two connector pins, and they perform different functions but the best method to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. If you are having problems with this part, check for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive reduction 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, 3 were drenched in gazoline, the fourth one was dry. When i crank the engine without sparks i put tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming the issue is in another place.
I also tried to reset PID without success. The car click here can start when the G28 is not plugged in and is running fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I feel like i've pretty much ruled everything else out. I'm afraid i read more may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can more info easily find click here one at a wrecking yard or in a local parts store. It is simple to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position website of the crankshaft in order to make decisions about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could cause an engine shutdown.
The signs of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal, and/or a misfire when in gear. If you have any of these issues, it is likely your sensor is failing and should be replaced. The good news is they are quite affordable and readily available, especially when you're looking at the Bosch unit which is what we have. Alternately, the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind many issues in your vehicle. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how the car's crankshaft is rotating. If this sensor fails, it could affect the performance of the transmission, as well as the other car's components.
The G5 engine speed sensor is located on the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via a grey wire. The ECU then processes this signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can check 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. It should show approximately 1000 ohms resistance between those points. This is a typical component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.