7 Small Changes You Can Make That'll Make A Big Difference With Your Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission just above the flywheel ring gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC and also where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two pins for the connector and they have different functions however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is in full operation. If you're having issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive drop in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. Today, i pulled out the spark plugs. Three were drenched with gazoline the 4th one was dry. When i crank the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stays shut. 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 is able to start when the G28 is disconnected and runs fine when it is connected, but still has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not sure what to do, as i feel i have pretty much eliminated everything else. I'm afraid i may have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. Test them out by putting 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 left on the black connector's side). how to open audi car key G28 Car Keys should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to know the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you're in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They are cheap and easy-to-find especially if they're an Bosch sensor like ours. You can also choose the GM version of this unit is also a great option.
5. Tachometer
A faulty engine speed sensor could be the reason behind many issues with your vehicle. It's an essential component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to malfunction and other car components to be affected.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU is then able to process the signal to control fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. You should observe around 1000 ohms of resistance between these two points. This is a standard part across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.