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Location:
Hobart
Registered:
June 2002
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factory locations of air temp sensors
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Wed, 22 September 2004 00:48
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i have mine mounted in the plenum. problem is it suffers from heat soak. even with a cold air intake i think the sensor is being heated up by engine heat and not representing the true air temp. This means the mixture is leaned out. not a problem in closed loop mode, but it effects my idle quality around town.
Where to factory MAP EFI systems locate their air temp sensors? below throttle body? in plenum?, any kind of insulation?
i was thinking of putting one in the air ducting further away from the engine.
im talking about N/A here.
thanks
Chris
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Registered:
May 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 01:50
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When mine was mounted in the plenum I suffered similar probs, I moved mine to the section of pipe just in front of the throttle body, this made a great diffrence. Mine is turbo charged, so it sits in the section of pipe between the intercooler and throttle body.
I would think (correct me if I am wrong??) that on a naturally aspirated car it would be ok to mount the air temp sensor anywhere between the air filter and plenum as the air temp is not likely to alter much in that time??
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Location:
Hobart
Registered:
June 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 02:09
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yeh sounds like ill have to set up somewhere to mount it away from the heat.
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 03:31
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Don't most later model engines have 2 temp sensors? My 3S had one in the air box and one in the plenum.
You say the sensor is suffering from heat soak, but wouldn't the plenum be suffering from heat soak as well? So having the sensor measuring the temperature in the plenum is a good idea.
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Location:
Hobart
Registered:
June 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 03:45
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yes all the metal around the plenum gets quite warm, but i dont think that this would be the temperature of the air going through it into the engine. Sure it probably heats up a bit, not that much though?
I think the sensor should give ,as close as possible, the temperature of the air going into the engine. but its probably measuring a temperature half way between the air temp and the temp of the alloy.
2 sensors hey?, interesting. i wonder how the computer deals with that, maybe averages them?
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Registered:
May 2002
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 07:56
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im with you mr ke38. Most factory systems have the temp sensor in the air box or the intake pipe. On turbo toyota's its usually in the air box or pipe before the turbo to avoid any risk of the thing bursting out under pressure.
Yes cool1 you are also right, but *this is a big I THINK* depending on the engine one of those sensors is for the air conditioning electricals.
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 09:37
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Both sensors control fuel mixtures.
Also if your temp sensor is suffering from heat soak its probably needs replacing. I did some testing on your situation this afternoon and there is no way for the sensor to be effected by heat out side the manifold.
All the sensors I have available have the thermistor insulated from the outside in a copper/brass tube. So its only the end of the tube thats is really sensitive to temp change.
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Location:
Brisbane
Registered:
February 2003
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 09:50
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fwiw: the air temp sensor in a v6 commode is in the manifold -
the actual sensor (NTC) is in a 'cage' of what looks like bakelite or high temp plastic
the barrel of the sensor is also aluminium
if you were running a turbo i would assume that the manifold is the best place for the sensor as tehECU will then know the tempreture of the air entering the engine (as opposed to the air temp entering a goddam hot thing like an air compressor).
i'll be mounting mine in the IC pipe just upstream of the TB - but in the 5M i'll use the vacuum port opposite the thermostat housing.
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Location:
Hobart
Registered:
June 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 10:57
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| Cool1 wrote on Wed, 22 September 2004 19:37 |
Both sensors control fuel mixtures.
Also if your temp sensor is suffering from heat soak its probably needs replacing. I did some testing on your situation this afternoon and there is no way for the sensor to be effected by heat out side the manifold.
All the sensors I have available have the thermistor insulated from the outside in a copper/brass tube. So its only the end of the tube thats is really sensitive to temp change.
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so you found that the sensor was only sensitive to the temperature on the very end?... interesting, i might do some testing of my own.
maybe my problem is that the sensor is not well insulated.
The sensor is actually a GM coolant temp sensor. the outside appears to be made from brass. i might try to insulate it from some heat as an experiment.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 11:01
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if it's a GM coolant sensor, the it will be thermally connected to the body of the sensor..
go and grab an air temp sensor, they are onyl about $20 new.
Cya, Stewart
ps, some of the turbo MS guys use a dab of silicon to stabilise the sensor disk inside the cage.. so it doesn't wiggle around and break off..
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 11:10
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Remember that the insulation in the temp sensor will break down after a few years and the sensor will need replacing.
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Location:
Hobart
Registered:
June 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 11:25
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kewl... yeh i used a coolant sensor because it was available easily 
got a GM part number? or a model of car i can quote?, or some toher source, i would like one with one of those rectangular connectors.
cheers all
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Registered:
May 2002
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Re: factory locations of air temp sensors
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Wed, 22 September 2004 23:59
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| Quote: |
Remember that the insulation in the temp sensor will break down after a few years and the sensor will need replacing.
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Arrrh, this is probably the real problem I had then, I didn't realise the insulating material would break down after a period of time (makes sense though).
I did some brief testing when I moved the sesnor, doing comparisons between the two positions over periods of time and I found the the new air temp sensor position (approx 40mm pre throttle body rather than approx 80mm post throttle body) was a worhtwhile move. Both my sensors are old though so both probably have poor insualting properties now.
Thanks for the tip, I may go get a new temp sensor and see what differences are made.
Cheers.
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