Temp Sensor

[t_marat]

I have seen a 1993 525i BMW M50TU. It did not have a temp sensor near the throttle body either.
I will check the underside of my manifold if it is there (it must be there).

[the knight rider]

yeah its towards the firewall pointing upwards, let me know please what you find.......

[ryan roopnarine]

the thing that you show in the realoem picture and the bentley picture is not the engine coolant sensor, it is the air intake temperature sensor. your market may not have them, the m50 2.5 vanos might not have them (i have a 2.5 m50 nonvanos that does). the coolant temperature sensor is located under your intake manifold. there are two sensors, side by side. one tells the engine computer the temperature, the other tells the temperature gauge in the dash what the temperature is. are you intentionally trying to change your air intake temp sensor? or are you tyring to change one of the coolant temperature sensors for engine problems? you don't need to remove the intake manifold to change the coolant temp sensors, i did so using both regular wrenches and a flexible handle ratchet.

[t_marat]

I wasn't looking for the coolant temp sensor. I was looking for the intake air temp sensor. I simply noticed that I don't have it in the place that the Bentley shows it should be.
So my engine might not have it at all?

[Jon K]

Engine has to have it - it retards ignition if IAT get too hot

[shogun]

This picture shows a cut-trough view of the air-mass sensor:
The air-mass sensor is completely electronic, no moving parts. It's also known as the hot-wire sensor. The sensor exists basically out of 2 parts: (1) is air intake temperature sensor and (2) is the heated wire.

The hot wire is heated to 100 degrees Celsius (180 F) above incoming air temperature when the ignition is turned on. So on a hot day, if the ambient air is about 30 degrees Celsius (86 F) the hot wire is heated up to 130 degrees Celsius (266 F). It doesn't glow at that moment. When you open the throttle, intake air flows over the hot wire and cooling the wire down. With more air passing the heated wire, the cooling effect is greater. The control circuit of the MAF is trying to keep the hot wire at the same original temperature of 100 degrees Celsius above ambient temperature. So the control circuit is applying more current flowing through the heated wire. This current is measured and converted into a voltage signal, which gives the DME an indication how much air is sucked into the engine.

That is at least how the MAF works on the 750 and on other cars which have the same MAF
http://bmwe32.masscom.net/sean750/MA...leshooting.htm

[t_marat]

Bentley says that M50 uses hot wire which has a burn off cycle. and that M50TU uses hot film MAF without a burn off cycle.
I think M50TU's do not have the temp sensor, or rely solely on the temp sensor in the MAF.

RIPN RAY, did you mean the coolant temp sensor or the air intake temp sensor?

[t_marat]

The temp sensor is located on the underside of the intake manifold, as Ray said. Attached is the pic of the intake manifold turned upside down. Its on the upper right of the pic, with two pins.