What would happen if the coolant temp sensor...

[Zentigrade]

...on my GTi were to short? Could it/would it cause the car to stall, and potentially not re-start
until the short, because the engine was hot, dried out?

[bunter]

yes it could. but those symptoms sound more the like "cutting out" syndrome that affects mk3`s

[Zentigrade]

Indeed it does, but the only fault I can find without replacing the list
of parts associated with the cutting out syndrome is with the coolant
outlet elbow, and the fact it leaks at the gasket, getting the sensor
area damp. Knew that was a problem to be addressed when I bought
the car last week. Didn't occur to me the sensor could well 'short'. Is there
a thread on 'cutting out syndrome' here so I can get more info if
the obvious turns out to be wrong? Sorry to be a pain and all

[Pete Taylor]

The coolant temp sensor is effectively a variable resister. When cold there is lots of resistance which tells the ECU that the engine is cold and adds more fuel which is needed for startup. As the car heats up the resistance is lowered gradually telling the ECU to gradually use less fuel as it warms up to running tempertature. If the coolant temp sensor is broken at any temperature range it will be telling the ECU that the engine is still cold which will give overfuelling problems when the engine is upto temperature. If the temp sensor is shorted it will have no resistance at all. This will constantly be telling the ECU that the engine is upto temperature. This will have an effect on startup as the ECU will not be letting the fuel pump/injectors provide enough petrol for starting

[firstgolfgti]

Here is the common cutting out thread http://www.golfgtiforum.co.uk/index.php?topic=2080.0 there's 30 pages but its worth the read.

[Zentigrade]

Thanks guys for the help. I've now got it going to a good local mechanic before I
spend a fortune on parts. Hopefully I'll post back next week with good news on
a solved problem

[Zentigrade]

Check that. Just read all 30 pages on this subject. I have 3 parts to change, the 3rd, the mechanic is gonna fit
Hours it's taken to read it all! 99% sure it's the, wait for it... Engine Speed Sensor or Crank Angle Sensor or Hall Sensor
or Knock Sensor or Pulse Sender... It's the same F***ing thing, why isn't there a standard name for it
That and I'll change the ECU relay, cos evidently the original is sh!t, and the fuel pump relay because evidently, the
original is... sh!t. Now, I have a light at the end of the tunnel, days of research spent. I'll post back....

[Pete Taylor]

I wouldn't say the original is sh!t, just not as good as it should be. It's lasted over 10 years already

[firstgolfgti]

I think you should find that the hall sensor is located under the dizzy. The knock sensor is in the engine block just behind the alternator bracket near a grounding block and the crankshaft sensor is down under the oil filter.

The crankshaft sensor is known as the engine speed sensor. But the camshaft position sensor on VAGCOM comes up as the Hall sensor.

Hope that helps

[Zentigrade]

Thanks. Oh why is it never easy...