Audi G28: The Good The Bad And The Ugly
How to Replace an audi replacement car keys a3 spare key (redirect to bookmark-nation.com) G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge 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
The grey wire is located at the edges of the transmission, just above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper timing chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
It can be a bit difficult to test since there are different connector pins, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is fully functional, it should read about 1000 ohms. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, 3 were drenched with gazoline the 4th one was dry. When I crank the engine with no sparks i put tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th one stays closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. I think the issue is elsewhere.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice 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 if i crank up the engine.
I'm not certain what to do, i believe that 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 can be activated by a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or at a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end 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 know both the speed and position of the crankshaft to determine timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.
Some of the symptoms of a failed G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when you are in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these symptoms. The good thing is that they are very cheap and easily accessible particularly in the case of a Bosch sensor, which is what we have. Alternately, GM's version this component is an option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many problems in your vehicle. It's a crucial component of the transmission in your audi key shell because it relays information to the ECU about how fast or slow the car's engine is spinning. If the sensor fails, it could cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends signals via gray wire to ECU pin T55/49. The ECU is then able to process this signal to control fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a common feature across the audi tt key 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du, so you might find good ones in wrecking yards.