High EGT's on gauge

[Ellisd]

Just got round to fitting my EGT gauge and i'm a little worried with the numbers I'm seeing  .  It show's right at ambiet (13 degrees c today checked against a thermometer)  And with the probe in boiling water I was seeing 96/97 degrees, so as far as I can tell i've calibrated it correctly.  When I take the car for a drive however the EGT values seem quite high.  450-500 on idle 600-750 on gentle cruise and 1000+ when on full load and high revs. 

This Car has only minor engine mods (filter, exhaust etc) so I was expecting to see such high temps.  It could well be the sensor is reading correctly, but is there any other way I can test the sensor before i go worrying any further?

[mattias]

Without having any information on the tune of your engine it's hard to say what is normal.  I could guess that you are using too little ignition advance, causing the engine to send still very much burning gases out into the exhaust = hot. More advance will lower the temperature, up to a point. You could be running really lean too..

[Ellisd]

Engione isn't tuned at all in all honesty.  Toyota Celica GT four with stock ECU and stock map. 

[jrussell]

If you've purchased it in the last couple of years, it would have come calibrated.

Are you sure you're reading in *C and not *F?

Is the sensor plugged directly into the gauge, or do you have an extension? If you have an extension, is it K type thermocouple wire? It's important.

Is the connection between the sensor and gauge a K type thermocouple connector? Again, this is very important because the whole way the sensor works is based on dissimmilar metals, you can't use copper wire or connectors and have it be accurate.

You could check with a multi-meter. It should be 38 micro volts per degree Celcius.

[Ellisd]

Are you sure you're reading in *C and not *F?
Definately set to degrees C

Is the sensor plugged directly into the gauge, or do you have an extension? If you have an extension, is it K type thermocouple wire? It's important.
Sensor plugged directly into gauge using supplied connector that came with the sensor

Is the connection between the sensor and gauge a K type thermocouple connector? Again, this is very important because the whole way the sensor works is based on dissimmilar metals, you can't use copper wire or connectors and have it be accurate.
As above

You could check with a multi-meter. It should be 38 micro volts per degree Celcius.
Great I'll check with a meter and see if it's a problem with calibration

The car's currently off the road but when it's up and running next weekend I'll see if I can get some data logs up.

Thanks for your help

[Ellisd]

what is the scale of the vems sensor, -50 to 1200 c?

if so would 0 degrees c be 1900 mV (38mV *50) or does the range start from 0?

[Ellisd]

Right after a bit more fiddling It seems that although the gauge is definately displaying degrees C the values seem to actually be Degrees F.  On powering up the sensor is showing -13 - -15 which is works out about right.  On Motorway cruise i'm seeing values of around 1000 which works out at 538 degrees C which is again quite believable.

[rob@vems.co.uk]

Are you using VEMSTune and a recent firmware?  I got massively confused the other week when I was playing with it as the whole configurable slots thing is far from clear when you first have a go!

[Ellisd]

last time i updated was about 2 months ago and I think that I used the last version without AIM support.  If I open up in megatune is there a possibility it will correct itself?  I'll have to see if I've got time sometime this week to have a play about

[rob@vems.co.uk]

Having the newest firmware didnt seem to hurt at all, you have all the setups for the slots and what have you.
Although... saying that I think MegaTune was the thing to use.  I've confused myself...

[Ellisd]

Right bit of an update:


Temp at steady Idle

Multimeter reading of thermocouple 204 mV if I remember correctly

Recalibrated the sensor to ensure everything was right


Ice

a little out using the calibration settings supplied in the box



boiling water

a little out, the magic number we're looking for is around 86

more like it

then the offset adjusted to give 100 for boiling water


At Idle we're sitting at about 600 now  so I fear still no further forward lol

[mattias]

After you adjusted the offset to make it read 100 C, did you check with ice water to see that it read 0 C correctly?

[Ellisd]

Started by putting the prob in ice.  This gave a reading of -13c.  I then prgressed to boiling water and got a reading of 72c I adjusted the calibration untill I got 100 degree difference between the ice and boiling water (-13 for ice and 85 for water).  It was only when i got to this point I adjusted the ofset to show 100 for boiling water