1.8T Intake temp sensor

[DrRich 1]

A quick question about this mod which I've read about in other places. I understand the idea that the IAT gets heat-soaked in the inlet manifold and tends to read about 20C all the time after the engine's been running a while. I also understand that the 1.8T sensor has an 'open' element, but I'm not sure why this wouldn't get heat-soaked too - isn't the Mk3 one just covered with a plastic cap which surely won't get soaked too much (plastic isn't much of a heat sink is it?).

I also read that the 1.8T version gives instant readings, but surely that's down to the ECU not the sensor (which is just a NTC resistor isn't it?).

So, simply:

With a standard ECU (OBD2) is there any advantage to this swap?

Which 1.8T engine code or does it not matter?

I've relocated my sensor to between the CAI and the MAF (long wire!!) and seem to get temp's only 1 or 2C above ambient; will I be able to improve on this?

I also have this niggling thought in my head that if the stock IAT behaves like this, then won't the stock fuel/ignition map be written around this - presumably the engineers mapped a standard engine rather than placing sensors in non-standard places...

Cheers for your time.

Rich

[FishWick 21]

You will never get lower than ambient without some kind of refridgeration method. That's why chargecoolers are so popular in the states - you can put ice in the water tank and get lower than ambient :-)

The problem with the standard IAT sensor is as you say, response time. It can take well over 20 seconds to register a change a temperature.

IAT is more critical with turbo engines, hence why VW used a more responsive one on the 1.8Ts and yep, your current software is tuned around the standard IAT sensor.

If you wanted to use the 1.8T one, you'd need to know the voltage to temp scale and input it into the software.

In short, it's not worth it.