Intake Temps

[S2 Ant]

This might seem a daft question but wondered if its possible.

Is it possible to alter the location of the external temp sensor so that it would measure intake temps instead?

Was just something i was wondering about, as i know what the weather outside is like lol

[kwlw]

From my point of understanding, it will measure temperature of intake manifold, not the air which is passing in it. If you want to see temperature of the air, you need to get temperature form air temp sensor which sits there.

I have a special hole in the intercooler for this sensor (later MC's had such thing), however not tested this sensor yet.

Sau

[S2 Ant]

Yeh thats what i meant, surely the sensor thats on the body somewhere could have the wires moved so they are mounted in the inlet tract so it would measure intake temps instead. It must have the range to do so i would have thought, was just wondering if its actually possible or whether it wouldnt update regularly enough to be practical

[Doug_RS2]

What a neat idea Ant - find out what type of sensor is used - and get an unshrouded one and mount it in the inlet, then splice that into the wiring. The external one is probably well shrouded/protected from the elements so will have a very slow response time - not good for measuring inlet temps.

[DAVIDP20V]

I can see it now "Ant's temperature mod" ! Top Idea! I just need the led coversion to get mine to light up.

[4WheelDrifter]

I thought about this idea, but I don't have the display on my S2.

[audiman]

That is a good idea, i too dont have the display in my car

[S2central.net]

Ant - fair play son - that IS the best suggestion you've ever had... in terms of using the ambient temp guage as a useful place to display IAT info... and you are to be heartily patted on the back for such ingenious thinking. However some concerns to get round first -

1. I doubt the ambient temp sensor has a suitable dynamic range or response time for the temps and trends we'd be looking for.

2. Dunno if the ATD module can cope with temps above 40 celsius

3. The ATD module makes some use of the vehicle speed to better estimate the real air temp depending on how fast the car is moving so do you disconnect the VSS wire for raw unfiltered info ?

4. Then there is the issue of where to mount the temp sensor - the intercooler exit, the pressure pipe or somewhere near the ECUs IAT sensor in the manifold ?

I'm NOT saying it won't work... just that significant thought, testing and calibration will be needed for this to be anyway accurate. Could be a doozy of an idea !

My mind for doing this is actually with a pair of pyrometers from Autometer - one for IAT and another for EGT - fitted to the slot currently occupied by an utterly useless device known as a radio !


Paul

[porkkis]

The sensor for out tems is probably WAY too slow. Give it a try, but don't expect too much...

For checking intake temps I would just:

- plug in a vagcom
- start the car and checking measure blocks for intake temp
- plug a DMM to the intake manifold temp sensor wires
- check that the DMM does not affect the values seen by motronic from the vagcom screen
- have a friend "manually log" resistances and vagcom intake temps while driving

That's about it.

I'm going to do this by using my friend's AAN motor as a reference as 3B does not show the intake temp at measure blocks

[porkkis]

Let me add that that's the procedure to find out what resistance means what temperature value. With this info you're able to measure 3B cars and build your own gauge if you're familiar with electronics.

[S2 Ant]

@ Paul, I was wondering if it would update fast enough, ive seen it change fairly rapidly whilst out before but not sure if it would be fast enough and as you say, not sure if it would have the range or not.

Im gonna look up on ETKA if the temp sensor is similar to that of the ones on a Mk2 Golf as a friend of mine has a few of them about and see if it can be stripped back so its more bare so in theory should increase the response from that end, as i would assume as Doug said, all the shielding on it would cause the slower reaction time to the temp change.

I wasnt aware that it makes adjustment according to speed tho.

Im gonna see what i can find out, as ive been thinking of this for ages but only rememebered to actually post about it the other day.

[Mihnea]

Wow, I had never heard of the ambient temp display using the vehicle speed either, are you sure about that, Paul? I guess I could check the wiring diagrams myself but I just don't have the time to do it right now...

Great idea, Ant, if it works we can call that the Ant Mod!!!

Cheers,

Mihnea

[The Spanish]

2. Dunno if the ATD module can cope with temps above 40 celsius
Paul

I have seen it at 45ºC (Beatiful Madrid Summer)

[S2central.net]

Check it out -

http://s2central.net/atd_intro.html

VSS is definitely hooked into the ATD module so its used somehow. I guess to prevent heat soak at idle causing the displayed ambient temp to rise - and to stop wildly low readings due to windchill at motorway speeds.

So maybe with VSS disabled the ATD sensor is quite sensitive. Would be easy to test that by hooking a DVM up to the bare sensor and see how rapidly the resistance changes with air temperature.

Hold it at ambient... put it in the fridge... hold it near and over a steaming kettle spout... breathe on it... f@rt on it... see if and how quick the value changes !


Paul

[S2central.net]

If the bare sensor is quick enough to react to ambient changes... then hook it up the ATD module as shown in the wiring link. Simply ignore the VSS input firstly and see how quickly the *displayed* temperature reacts to what is going on.


Paul