Audi G28: 10 Things I Wish I'd Known Sooner
Audi G28: 10 Things I Wish I'd Known Sooner
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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. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored 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 above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors according to the situation.
If this sensor fails the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two pins for the connector and they perform different functions however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. If you are having problems with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth one was dry. When i crank the engine with no sparks i put tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.
I also tried to reset PID without success. The car will start when the G28 is not plugged in and is running fine when it is connected but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. However, i'm afraid that I might have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from 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 wrecking yard or from a parts store. It is easy to test them - just switch your DMM into resistance mode and determine the distance between pins 1 here and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues website with either one of these, the diagnostic scanner will show the codes that could trigger an engine shutdown.
The signs of a failing G28 sensor are an inaccurate rev counter in the gearbox the gears are shifting audi a1 car key faster than normal and/or a misfire when in gear. If you are experiencing any of these problems, it is likely that your sensor is deteriorating and requires replacement. The good news is that more info they are very affordable and easy to find, especially in the case of a Bosch sensor, which is what ours are. Alternatively, the GM version of this part is also a good choice.
5. Tachometer
A failing engine speed sensor click here could be the reason behind numerous problems in your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU regarding how fast or slow the car's engine is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate fuel and boost, as well as timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should detect a resistance of approximately 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find them in wrecking yards.