What's The Ugly Real Truth Of Audi G28
What's The Ugly Real Truth Of Audi G28
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How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission, above the flywheel gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control boost and fuel. It also sends an indication to the G5 tachometer in the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of a chain stretch 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 challenging because there are two pins for the connector and they serve different purposes but the best way to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was dry. When I crank the engine with no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th one stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. I'm assuming the issue is elsewhere.
I also tried to reset the PID without success. The car can start when the G28 is disconnected and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not certain 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 share them! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and both are used in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is simple to test them - put your DMM in resistance mode and measure the resistance 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 website should be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes bad you will get codes on the diagnostic scanner which could cause engine shut down.
A damaged G28 sensor could cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, and/or a misfire in the gear. If you experience any of these issues it is most likely that your sensor is failing and should be replaced. They're inexpensive and easy to locate especially in the case of an Bosch model like ours. Alternatively, GM's version of this component is an option.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It check here is a crucial part of the Audi's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. If this sensor fails, it could disrupt the performance of the transmission and the other car's components.
The G5 engine sensor is located at the outskirts new audi car key of transmission, above the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost as well as timig. It more info also relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster audi a3 key replacement pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is a standard component across the Audi 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.