E30 Zone

318i M40
Just out of interest how can i test the blue temp sensor, i read some where that you can do it with a test meter (did a search but cant find it). I have just changed this sensor but it still dies at idle until it warms up

thanks

-run the engine until it's normal operating temp.
-let it idle.
-disconnect the blue sensor (with engine running)

this should result in incerase of revs in the engine, it should be very noticable (on my m20 it incerased revs to nearly 2krpm, from normal 800 idle), shut of the engine after 1 or 2 seconds. you should smell petrol from the exhaust

basically when you disconnect the sensor the ECU thinks the engine is very cold (like 40 below 0 deg C), pouring fuel all over the place....

Measured from a good blue sensor a couple of years ago:
Resistance in cold water = 3400 ohms
In hot water from tap = 980 ohms
In very hot water = 306 ohms

This was a sensor used to repair a 318i which ran poorly when hot, with excessive fuel consumption. the readings from the original sensor were:
Cold = 7200 ohms
Hot water 1960 ohms
Very hot water 722 ohms.

I believe the base figure for the sender is 2500 ohms @ 20deg C

Did a load of tests on and old sender that came out of my 318iS, but during the tests i realised my thermocouple was knackered so had to abort tests....

Where can you find the blue temp sensor on the M40 engine?

magnumlove wrote:Where can you find the blue temp sensor on the M40 engine?

If you stand on the passenger side of the engine bay the plug is right under the inlet manifold screwd into the engine.

Its very hard to get at, i took off the big rubber hose from the AFM to the TB for better access, also there is a black plastic square tube which runs in front of the sensor undo the two bolts holding it, it will only drop about 1" or so but its all you need to line up the 19mm deep socket, also find someone with small hands and long fingers as its dam fidderly job!

dizz wrote:

magnumlove wrote:Where can you find the blue temp sensor on the M40 engine?

If you stand on the passenger side of the engine bay the plug is right under the inlet manifold screwd into the engine.

Its very hard to get at, i took off the big rubber hose from the AFM to the TB for better access, also there is a black plastic square tube which runs in front of the sensor undo the two bolts holding it, it will only drop about 1" or so but its all you need to line up the 19mm deep socket, also find someone with small hands and long fingers as its dam fidderly job!

I didn't realise it was so hard to access on the M40 engine, on the M42 you have a clear line of sight, 2 minute job!

E30Mark wrote:

dizz wrote:

magnumlove wrote:Where can you find the blue temp sensor on the M40 engine?

If you stand on the passenger side of the engine bay the plug is right under the inlet manifold screwd into the engine.

Its very hard to get at, i took off the big rubber hose from the AFM to the TB for better access, also there is a black plastic square tube which runs in front of the sensor undo the two bolts holding it, it will only drop about 1" or so but its all you need to line up the 19mm deep socket, also find someone with small hands and long fingers as its dam fidderly job!

I didn't realise it was so hard to access on the M40 engine, on the M42 you have a clear line of sight, 2 minute job!

It is quite hard to see mate as it goes, unless you know where it is you won't find it and same goes for reaching it, it's a bastard!!

Cheers guys, I'll give it a go looking for it!! The Haynes Manual I was using is shite