Why People Don't Care 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. This sensor is located near the transmission's edge, above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using the grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and where the camshaft lies to trigger the spark and injectors.
If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
Testing can be a bit difficult because there are two connector pins, and they perform different functions but the best method to test it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms when it is in full operation. Check for evidence of coolant or oil in the connector bay if there are problems with this part.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors aren't firing anymore. Today, i pulled out the spark plugs. Three were drenched with gazoline the fourth one was dry. I put a piece of tissue over each injector hole, and when i turn the engine on without sparks, the ones that have gazoline pop right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is elsewhere.
I also tried to reset the PID with no success. The car can start if the G28 is unplugged and runs fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. Also, how much is a replacement audi key noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I feel like i've pretty much eliminated everything else. However, i'm afraid that i might have missed something. If anyone has any ideas please let me know! TIA!
3. Fuel Pump
The fuel pump in 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 which is why you can easily locate one at a salvage yard or in a local parts store. It is simple to test them to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.
A failing G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire in gear. If you are experiencing any of these issues, it is likely your sensor is going bad and requires replacement. The good news is that they are very cheap and easily accessible particularly if you're looking at a Bosch unit which is what ours are. Alternately, GM's version this part is an excellent choice.
5. Tachometer
A faulty engine speed sensor could be a cause for many issues with your car. It is a crucial part of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. If the sensor fails, it will affect the performance of the transmission, as well as the rest of the car's components.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends a signal via an uncolored wire to the ECU pin T55/49. The ECU then processes this signal to control fuel, timig and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those two pins. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find good ones in wrecking yards.