Audi G28 10 Things I Wish I'd Known Earlier
Audi G28 10 Things I Wish I'd Known Earlier
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How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission just above the flywheel ring 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
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky since there are two pins for the connector and they serve different purposes but the best method to test it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when it is operating at its maximum. If you are having problems with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll i had a big cut in power like the engine is out of gas or the injectors aren't firing any more. This morning i pull out the spark plugs. Three were soaked with gazoline and the fourth one was dry. When I crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I think the issue is elsewhere.
I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I'm not sure what to do, i feel i have pretty much eliminated everything else. I'm worried that i might 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 by the RPM sensor. The GM-style sensor is the same as the G4 and they both work check here in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or from a parts store. It is easy to test them - just what is the audi advanced key switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed the crankshaft to determine fuel injector timing, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
A malfunctioning G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or an unfire when in gear. It is likely that the sensor is failing more info and requires to be replaced if you notice any of these symptoms. The good thing is that they are very affordable and easily accessible, especially in the case of an Bosch unit like ours. You can also choose the GM version of this part is also a good option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems in your vehicle. It is an important part of the transmission in your Audi because it relays information to the ECU on how fast or slow the car's engine is turning. If this sensor fails, it could affect the performance of the transmission as well as the other get more info car's components.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits a signal via a gray wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the audi spare keys ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. There should be the resistance to be around 1000 ohms between these two points. This is a typical part that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.