Why The Biggest "Myths" Concerning Audi G28 Could Actually Be Accurate
Why The Biggest "Myths" Concerning Audi G28 Could Actually Be Accurate
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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 a grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using an uncolored wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.
If this sensor fails to function, the ECU will display an error code P00160. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
It is a little tricky to test as there are several pins on the connector and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when it is at full operation. If you're having issues with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power like the engine is running out of gas or injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the 4th was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 that were drenched in gazoline leap out, however the 4th stay closed. I checked the ground connection of ECU pins 14,30 and here 48/55. I found 0ohm. I think the issue is elsewhere.
I also tried to reset the PID but with no luck. The car will start if the G28 is unplugged and runs fine when it is connected but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.
I'm not sure what to do. I believe that I've eliminated everything else. But i'm worried that I may have missed something. If anyone has suggestions, please get more info chime in! TIA!
3. website Fuel Pump
The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. It is easy to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the check here position and speed of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could lead to the engine shutting down.
A website damaged G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or an unfire when in gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these signs. The good news is they are quite affordable and easy to find, especially if you're looking at an Bosch model, which is what ours are. You can also choose the GM version of this part is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues in your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU regarding how fast or slow the engine is turning. This sensor could cause the transmission to fail and other components in the car to be affected.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU, so you might find them in wrecking yards.