How To Outsmart Your Boss On Audi G28

How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission, above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, 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 uses this information to control fuel, timig and boost. It also sends an indicator 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 needs to know when the crankshaft has reached TDC, and the location of the camshaft in order to activate the spark and injectors.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain stretching or a jump 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 as there are two different pins for the connector and they perform different functions but the most effective way to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when it is at full operation. Examine for signs of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive drop in power. It was like the engine had run out of gas. Or, my injectors weren't firing. Today, i pulled out the spark plugs. Three were drenched in gazoline, the fourth one was dry. When I crank the engine without sparks i put tissue on the top of each of the injector holes, the 3 drenched with gazoline pop out, but the 4th stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. article source assume that the problem is elsewhere.

I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c, even if I unplug 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 think I've eliminated everything else. However, i'm afraid that I might have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is simple to test them - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions about timing of the fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go badly, you will see codes on the diagnostic scanner that could cause engine shut down.

Some of the symptoms of a failed G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when in gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these signs. They're cheap and easy to find, especially when they're an Bosch model like ours. Alternatively, GM's version of this component is an excellent choice.

5. Tachometer

A failing engine sensor could cause a variety of issues in your vehicle. It's a vital component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it can affect the performance of the transmission and the other car's components.

The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 range, 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.

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Pub: 18 Mar 2024 06:28 UTC
Views: 547