What's The Ugly Truth About Audi G28
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 situated near the edges of the transmission, above the flywheel ring gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using a grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
audi key replacement serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC, and the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain stretching or a jump link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult since there are two connector pins, and they perform different functions however the best method of testing it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is operating at its maximum. If you are having problems with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the fourth was dry. I placed a tissue over each injector hole and when I start the engine without sparks, the ones with gazoline jump out. The fourth one remains shut. I checked the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I think the issue is in another location.
I also tried to reset the PID with no success. The car will start if the G28 is unplugged and it runs perfectly when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.
I'm not sure what to do, as i believe that i've eliminated everything else. I'm concerned that 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 by 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 easily find one at a salvage yard or from a parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position 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 either of these sensors go badly, you will see codes on the diagnostic scanner that could cause engine shut down.
The signs of a failing G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you are experiencing any of these issues, it is likely that your sensor is failing and needs replacing. They're cheap and easy to find especially in the case of an Bosch sensor like ours. Alternately, the GM version of this unit is also a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind many issues with your car. It's a vital component of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. If this sensor fails, it can cause problems for the transmission and the other car's components.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, and also to timigrate. It also transmits 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 on pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. audi lost key replacement should observe approximately 1000 ohms of resistance between those two pins. This is a typical part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.