In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) and then to the tachometer within 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 via the grey wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC and also the location of the camshaft in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display an error code P00160. click through the following web site indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jump in the chain link of the upper timing chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging because there are two pins for the connector and they serve different purposes but the most effective method to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading about 1000 ohms. Look for evidence of coolant or oil in the connector bay if you are experiencing problems with this part.
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 aren't firing any more. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth was dry. When I start the engine with no sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th one stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID but without success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. But i am afraid I might have missed something. If anyone has suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must know the position and speed of the crankshaft in order 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 you have a problem with either one of these, the diagnostic scanner will show codes that could cause an engine shutdown.
A failing G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire while in the gear. If you are experiencing any of these issues it is likely your sensor is going bad and should be replaced. They're inexpensive and easy to locate particularly when they're an Bosch model like ours. Alternately, the GM version of this component is also a good option.
5. Tachometer
A damaged engine sensor could cause a number of problems within your vehicle. It's a vital component of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor could cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then processes the signal to control fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins 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 see an average resistance of 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU, so you might find good ones in wrecking yards.
