20 Myths About Audi G28: Dispelled
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 near the transmission's edge over the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate 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 supplied by other sensors (G4 or G40).
Testing is a bit tricky since there are two connector pins, and they perform different functions however the best method to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should read about 1000 ohms. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss as if the engine was running out of gas or the injectors are not firing at all. I pulled out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th stays shut. I checked 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 without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. Also audi replacement key 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 don't know what to do. I think I've all other possibilities out. I'm worried that i might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical 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 a parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed the crankshaft in order to make a decision about fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will show codes that could lead to the engine shutting down.
The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when you're in gear. It is possible that the sensor is failing and requires to be replaced if you experience any of these signs. They're cheap and easy to find particularly if they're an Bosch unit like ours. Alternately, the GM version of this component is also a great option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of issues in your vehicle. It's a vital component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is turning. If the sensor fails, it will disrupt the performance of 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 and transmits 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 checking continuity from the sensor to the tachometer. Also, 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 detect an average resistance of 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du So, you may find them in wrecking yards.