20 Myths About Audi G28: Dispelled
20 Myths About Audi G28: Dispelled
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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. This sensor is located on the outside of the transmission over the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on 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 signals 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 as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors accordingly.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit challenging as there are two different pins for the connector and they perform different functions but the most effective method to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should read about 1000 ohms. If you're experiencing issues with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or injectors aren't firing any more. This morning i pull out the spark plugs. Three were soaked with gazoline and the 4th one was dry. I put a piece of tissue over each hole in the injector and when I start the engine with no sparks, the ones with gazoline jump right out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.
I also read more tried to reset the PID with no success. The car is able to start if the G28 is unplugged and is running fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when it is unplugged, 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 if i crank up the engine.
I'm not sure what to do, as i think i've pretty much ruled out everything else. I'm worried that i might have missed something. If anyone has any ideas 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 transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is simple to test them: simply put your DMM into resistance mode and test the check here distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that has to know the speed and position of the crankshaft to make decisions about fuel injector timing etc. To do website this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these, the diagnostic scanner will show the codes that could trigger website an engine shutdown.
A malfunctioning G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or an unfire when in the gear. If you are experiencing any read more of these issues it is most likely that your sensor is deteriorating and needs replacing. The good thing is that they are very cheap and readily available particularly when you're looking at the Bosch sensor, which is what ours are. Alternatively, the GM version of this component is also a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind numerous issues with 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 cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to control the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. You can also 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 and pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.