Audi G28's History History Of Audi G28
Audi G28's History History Of Audi G28
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How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49) and then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU then uses this information to control fuel, timig and boost. 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 must know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper timing chain. However, the error 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 connector pins, and they serve different purposes but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms when the sensor is at full operation. Check for evidence of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power as if the engine was running out of gas or the injectors are not firing any more. This morning i pull out the spark plugs, three were drenched with gazoline the 4th one was dry. I put a piece of tissue over each injector hole, and when i start the engine with no sparks, the ones that have gazoline pop right out. The 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I assume that the problem is in another location.
I also tried to reset the PID without success. The car is able to start if the G28 is disconnected and it runs perfectly when it is plugged in but it still 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 when the actual pressure is 0.0 when i audi spare key rev the engine.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. I'm afraid i may have missed something. If anyone has any ideas please let me audi a1 key know! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80, 100, 200, UrS and RS2 cars read more so you can easily find one at a salvage yard or from a parts store. It is simple 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
The ECU of our 20vt turbo (3B AAN ABY) engines needs to be aware of the speed and position of the crankshaft in order to make a decision about timing of fuel injectors, etc. It makes use of advanced key audi a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.
A damaged G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire in gear. If you have any of these issues it is most likely that your sensor is going bad and should be replaced. The good thing is that they are read more quite affordable and readily available, especially when you're looking at a Bosch sensor, like ours. You can also choose the GM version of this part is also a great option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems in your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is spinning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU uses this signal to regulate the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find good ones in wrecking yards.