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Megasquirt air temperature sensor
TrophyJem - 6/5/14 at 12:35 PM

Hi all,

I have yet another megasquirt question.

I need to buy an air temperature sensor. I've done a bit of a search, but I'm struggling to find what is the best one to buy.

Any suggestions gratefully received.

On the water temp side of things I'm planning on using the standard duratec one. I think I need to change a resistor value for this?

Cheers

matt_gsxr - 6/5/14 at 12:48 PM

In my experience you need a MAT (manifold air temperature) sensor that adapts quite quickly to the air temp (i.e. minimal thermal mass).

I made one with a Maplin thermistor, which is quick and easy (I already had the housing and plugs from a gsxr600 one, so I merged the two things together), works well. (the gsxr600 sensor didn't measure the air temperature very well because it was brass and chunky).

Any dedicated automotive air temp sensor should do. You will just need to know the resistance at 3 temperatures (ideally spanning your anticipated temperature range).

In MS1 you need to adapt the temperature look-up for the resistance using the EasyTherm program.
In MS2 and above there is a simple drop-down for this.

TrophyJem - 6/5/14 at 01:59 PM

Its an MS2, so its really just a case of finding one that I can sensibly bolt to the air filter back plate on the throttle bodies?

JAG - 6/5/14 at 02:41 PM

I bought one of these HERE



Supposed to be a fast response sensor.


[Edited on 6/5/14 by JAG]

matt_gsxr - 6/5/14 at 03:02 PM

quote:
Originally posted by TrophyJem
Its an MS2, so its really just a case of finding one that I can sensibly bolt to the air filter back plate on the throttle bodies?


Yup, get an open MAT sensor and get the plug that goes with it.

The only possible gotcha is that for some the resistance is miles from that of the bias resistor, then you can lose some accuracy because of digitisation errors. The bias resistor is 2.5kOhm and you can always change it. In practice the accuracy you need for MAT and CLT are plenty good enough and to run into this problem in a significant way you would need something with super high resistance (like 100kOhm).

Any MAT sensor from DIY autotune will be fit for purpose (as suggested)

DW100 - 6/5/14 at 06:52 PM

This one is very useful

http://www.bosch-motorsport.de/en/de/produkte/catalog_products_1_34362.html

Bosch part No. 0 280 130 039

It is a very common sensor and is available from factors or ebay etc.

It uses a standard mini timer plug and has an M12 thread for easy fixing.

[Edited on 6/5/14 by DW100]

big-vee-twin - 6/5/14 at 07:36 PM

you can buy the auto tune ones or those sold on extra EFI by Phil.

If you use the standard Ford items you measure the resistance of the sensor in the fridge, in steam and under your arm and put these temperature and resistance values into the sensor wizard in the MS software don't need to change resistors.

There's a guide on how to do this in the mega manual.

I just measured the values and programmed the software.

coyoteboy - 6/5/14 at 08:22 PM

My favourite is the RIAT temp sensor range, they are very open and fast responding but I can't find a link just now. I paid 14 quid for it.
Don't really need the fast response on a naturally aspirated engine though.

[Edited on 6/5/14 by coyoteboy]

TrophyJem - 6/5/14 at 08:33 PM

Cheers for all the replies

That should point me in the right direction

I'm sure I'll be along with another question very shortly

omega 24 v6 - 6/5/14 at 08:45 PM

I used the std Vauxhall one and it worked straight from the box. Ms1 V2.2
Gotta be hundreds out there in the scrapyards

matt_gsxr - 6/5/14 at 10:08 PM

quote:
Originally posted by coyoteboy
My favourite is the RIAT temp sensor range, they are very open and fast responding but I can't find a link just now. I paid 14 quid for it.
Don't really need the fast response on a naturally aspirated engine though.

[Edited on 6/5/14 by coyoteboy]


Warm starts can result in heat soak into the sensor. Fast response is always better.

TrophyJem - 8/5/14 at 11:53 AM

So do we think one of these will do the job?

RENAULT 19 CLIO LAGUNA NEW ENGINE MANAGEMENT AIR TEMPERATURE SENSOR

Nice and cheap

coyoteboy - 8/5/14 at 12:26 PM

quote:
Originally posted by matt_gsxr
quote:
Originally posted by coyoteboy
My favourite is the RIAT temp sensor range, they are very open and fast responding but I can't find a link just now. I paid 14 quid for it.
Don't really need the fast response on a naturally aspirated engine though.

[Edited on 6/5/14 by coyoteboy]


Warm starts can result in heat soak into the sensor. Fast response is always better.


Sure, it's always better to be faster but fast or slow sensor will both soak, it's just a case of how fast a recovery you see after the hot start - 10 seconds or 0.5 seconds. I always buy the faster ones but in my experience it's not necessary - never had a hot start problem due to heat soak. I've had hot idle problem due to soak with a fast responding sensor in a metal body (manifold heat conducted through the body giving false reading) but that would happen with either too.

britishtrident - 8/5/14 at 01:19 PM

Pre 2002 Rover K series are easy to remove from scrappers it has a green connector and screws into the intect tract for no4 cylinder. The connector type is a standard mini-timer.

Rover 200 / 211 / 214 / 216 / 218 / 400 / 414 / 416 / 418 Air Temperature Sensor

[Edited on 8/5/14 by britishtrident]