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 located on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to regulate boost and fuel. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors accordingly.
If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump 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 can be a bit difficult because there are two connector pins and they have different functions but the most effective method of testing it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if you have issues with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is out of gas or injectors are not firing any more. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine without sparks, the three with gazoline jump out. The fourth one remains closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero Ohm. I assume that the problem is in another location.
I also tried to reset PID but without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c even when i unplug it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do, but i think i've pretty much ruled out everything else. I'm concerned that i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or parts store. It is simple to test them - simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to determine 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 sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.
A malfunctioning G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or an unfire when in gear. If you experience any of these issues, it is most likely that your sensor is failing and should be replaced. They're inexpensive and easy to locate, especially if they're an Bosch sensor like ours. Alternately, GM's version this component is an option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems within your vehicle. It's an essential component of your Audi's transmission, since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. If this sensor fails, it will affect the performance of the transmission, as well as the other car's components.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU then processes the signal to control fuel, timig, and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. There should be an average resistance of 1000 ohms between these two points. audi key replacement near me is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU So, you may find good ones in wrecking yards.