Notes

Why The Biggest "Myths" About Audi G28 Could Be True
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 transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

It is located on the outside 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 the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located 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 has reached TDC and also the position of the camshaft, to trigger the spark and injectors.

If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain stretching or a jump link on the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test since there are various pins on the connector, and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is functional, it should read around 1000 ohms. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge drop in power. It was like the engine had run out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. I placed a tissue over each hole in the injector and when I turn the engine on without sparks, the 3 with gazoline jump right out. The 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I'm assuming that the issue is elsewhere.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is disconnected and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I feel like i've pretty much ruled everything else out. However, i'm afraid that I may have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a 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). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft to determine fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go badly, you will see codes on the diagnostic scanner that could cause engine shut down.

The signs of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If replacement audi car key have any of these issues, it is likely that your sensor is going bad and requires replacement. They're inexpensive and easy to locate, especially if they're an Bosch model like ours. Alternatively, the GM version of this component is also a good option.


5. Tachometer

A damaged engine sensor could cause a number of problems in your vehicle. It's a vital component of the Audi's transmission as it sends information to the ECU about how the car's crankshaft is rotating. When this sensor fails, it can disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the 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 T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between those two pins. 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 You may also find some good ones in wrecking yards.

Website: https://www.thekeylab.co.uk/audi-car-keys/