Audi G28 10 Things I'd Like To Have Known Earlier
Audi G28 10 Things I'd Like To Have Known Earlier
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How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge over the flywheel gear. It transmits 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 grey wire is situated on the edge of transmission, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors according to the situation.
If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging since 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. When the sensor is fully operational, it should be reading around 1000 ohms. Examine for evidence 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 maximum speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs, three were soaked with gazoline and the 4th one was dry. I placed a tissue over each injector hole, and when I start the engine without sparks, the three that have gazoline pop right out. The 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is somewhere else.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. But i'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. It is simple to test them - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the speed and position of the crankshaft to make decisions about timing of the fuel injectors, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.
Some of the symptoms of a failing G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal, and/or a misfire when in gear. If you experience any of these problems, it is most likely that your sensor is deteriorating here and should be replaced. The good news is they are very cheap and easy to find, especially if you're looking at a Bosch model, like ours. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A damaged engine sensor could cause a variety of issues in your vehicle. It's an essential component of the transmission of your Audi, as it transmits information to the ECU about how fast or slowly the engine is spinning. This sensor could cause the transmission to fail and read more other car components to be affected.
The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, read more via an uncolored wire. The ECU then uses and processes this signal to regulate the flow of fuel, timig and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also get more info check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms between these points. This part is common across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find good website ones in wrecking yards.