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The mkiv Supra Owners Club

Inaccurate(?) temperatures


cheekymonkey

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My temperature gauges are annoying me, as they seem to be next to useless for monitoring anything:

 

1. EGT (probe mounted in ex. manifold)

 

This seems to work OK for normal driving, but as soon as I'm driving in a spirited manner, it peaks at 990 degrees and stays there for some time, even if I come off the throttle and start to idle, it will take 1-2 mins for it to come back down to sensible figures. This can't be right, can it!?

 

2. Oil (Sensor in sump plug)

 

Perhaps I made a bad choice with the sensor position, but I don't think I'm getting a "live" picture of my oil temp. Will the sump plug be in a good enough position for oil flow? What I see is that I get to about 100 degrees after a spirited drive, but it takes a long time for it to come back down again.

 

3. Water (sensor in top hard pipe "hose")

 

Reads 10-15 degrees higher than my Apexi Power FC which is using the stock sensor. Where's the stock sensor and would that explain the difference in temp I am seeing?

 

Any hints from the tech guys please? :)

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  • 2 weeks later...

What readings do you get on the water temp on normal driving and what about on spirited driving? I´m only asking as I installed a water temp gauge (sensor is located on the upper radiator hard pipe) and it´s reading pretty high values. Normally it´s about 90-92c and on spirited driving it can reach nearly 100c :shock:

Edited by Kite (see edit history)
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It sounds like either your gauges are no good, or the sensors are incorrectly mounted/fitted. The EGT should be fast to react , so that one is very suspect right away.

 

Edit - just realised this was an old thread, sorry, not sure why it was bumped.

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1. EGT (probe mounted in ex. manifold)

If you back-off the throttle entirely whilst slowing, NO fuel will go into the engine, so no internal cooling will be taking place. At the end of a lap at the 'Ring, where you could be crossing the finish line at 140mph plus but then have 1/3~1/2 mile off the throttle to loose that speed before leaving the track, I was putting the car into neutral and blipping the trottle, to both get fuel into the engine for cooling, and to MOVE the gas through the exhaust system instead of having super hot just been thrashing it exhaust gas sat there doing nothing,- well certainly nothing benficial for the car! :eek:

 

2. Oil (Sensor in sump plug)

There is a lot of engine to cool down - i.e. a lot of latent heat stored up in it after a spirited drive - it will take a fair while for the oil to cool, especially if you're got the bonnet shut and/or no airflow through the engine bay (e.g. static)

 

 

3. Water (sensor in top hard pipe "hose")

 

pass on that one

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If you back-off the throttle entirely whilst slowing, NO fuel will go into the engine, so no internal cooling will be taking place. At the end of a lap at the 'Ring, where you could be crossing the finish line at 140mph plus but then have 1/3~1/2 mile off the throttle to loose that speed before leaving the track, I was putting the car into neutral and blipping the trottle, to both get fuel into the engine for cooling, and to MOVE the gas through the exhaust system instead of having super hot just been thrashing it exhaust gas sat there doing nothing,- well certainly nothing benficial for the car! :eek:

 

The pistons will still be acting as big air pumps, pumping cool-ish air through the exhaust system though surely? I'd have thought this would cool things down quite effectively... but I'm not an expert :)

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The pistons will still be acting as big air pumps, pumping cool-ish air through the exhaust system though surely? I'd have thought this would cool things down quite effectively... but I'm not an expert :)

 

Not with the throttle closed (unless you have a huge leak :)

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The pistons will still be acting as big air pumps, pumping cool-ish air through the exhaust system though surely? I'd have thought this would cool things down quite effectively... but I'm not an expert :)

AIUI, it might cool to a degree but certainly not as much as chucking fuel in there to help AND you'll get further cooling capcity by blipping the throttle to increase the revs (and thus the gas flow through the cylinders and the exhaust.) A gust is better than a breeze, in simple terms. That's my not-that-technical personal view on the matter and I could well be wrong. *sits back and waits to be told he's wrong*

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