Air temp sender test proceedure ?
10-20-2008, 08:24 PM
#1
Pro
Thread Starter
Air temp sender test proceedure ?
re: S4 mtr -- the air temp sender that is located on top of the intake manifold,
When it's on it's way out, does it just die or can it fail slowly and cause intermittent
hot start problems. Is there an ohm test that can be performed to see if it's still with in specs. Or what other method is used to check to see if it's functioning properly. I've already lubed the ISV, it seems to be working ok.
Thanks..
When it's on it's way out, does it just die or can it fail slowly and cause intermittent
hot start problems. Is there an ohm test that can be performed to see if it's still with in specs. Or what other method is used to check to see if it's functioning properly. I've already lubed the ISV, it seems to be working ok.
Thanks..
10-20-2008, 09:41 PM
#2
Electron Wrangler
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Its just a thermal switch - normal condition should be open-circuit. If it is closed circuit when cold it has failed. This one on top of the intake manifold/plenum has no real effect on hot starting only on the cooling fan operation.
Maybe you mean one of the other temp senders.
Alan
Maybe you mean one of the other temp senders.
Alan
Last edited by Alan; 10-21-2008 at 08:36 PM. Reason: sp
10-20-2008, 10:06 PM
#3
Pro
Thread Starter
Well, I thought it was the one that lets the ecu know if the mtr is hot or cold so it can
adjust the rich - lean settings accordingly -- not the one associated with the cooling fan
operation -- Thanks ..
adjust the rich - lean settings accordingly -- not the one associated with the cooling fan
operation -- Thanks ..
10-21-2008, 06:15 PM
#4
There are three temp sensors on the intake manifold:
1. The air temp sensor located in the intake manifold towards the rear is used to turn on the fans. It will activate the fans after the engine is turned off.
2. The sensor that affects the running of the engine is called the Temp II sensor and is located near the front of the intake manifold towards the drivers side. It is two sensors built into a single probe.
3. There is also a temperature switch in the front towards the passenger side (I think it is used for the dashboard indicator).
Hope this helps.
David
1. The air temp sensor located in the intake manifold towards the rear is used to turn on the fans. It will activate the fans after the engine is turned off.
2. The sensor that affects the running of the engine is called the Temp II sensor and is located near the front of the intake manifold towards the drivers side. It is two sensors built into a single probe.
3. There is also a temperature switch in the front towards the passenger side (I think it is used for the dashboard indicator).
Hope this helps.
David
10-21-2008, 07:18 PM
#5
Pro
Thread Starter
David,
Are you sure the sensor located in the intake manifold towards the rear is for the fan operation ? and
not a air temp sensor for the ecu ?? I'm not sure but I thought it was, if it's not then were is the "air"
temp sensor located on the mtr because the other two you pointed out are in a water jacket .
Thanks for any input..
Are you sure the sensor located in the intake manifold towards the rear is for the fan operation ? and
not a air temp sensor for the ecu ?? I'm not sure but I thought it was, if it's not then were is the "air"
temp sensor located on the mtr because the other two you pointed out are in a water jacket .
Thanks for any input..
10-21-2008, 08:25 PM
#6
Electron Wrangler
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Why do you assume it must be an air Vs. water temp sensor?
The one right on top of the manifold as you described is the fan switch - as was already noted twice.
But of course you can believe what ever you want about it.... or you could just test it to be sure...
Alan
The one right on top of the manifold as you described is the fan switch - as was already noted twice.
But of course you can believe what ever you want about it.... or you could just test it to be sure...
Alan
10-21-2008, 08:49 PM
#7
Under the Lift
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There are three temp sensors on the intake manifold:
1. The air temp sensor located in the intake manifold towards the rear is used to turn on the fans. It will activate the fans after the engine is turned off.
2. The sensor that affects the running of the engine is called the Temp II sensor and is located near the front of the intake manifold towards the drivers side. It is two sensors built into a single probe.
3. There is also a temperature switch in the front towards the passenger side (I think it is used for the dashboard indicator).
Hope this helps.
David
1. The air temp sensor located in the intake manifold towards the rear is used to turn on the fans. It will activate the fans after the engine is turned off.
2. The sensor that affects the running of the engine is called the Temp II sensor and is located near the front of the intake manifold towards the drivers side. It is two sensors built into a single probe.
3. There is also a temperature switch in the front towards the passenger side (I think it is used for the dashboard indicator).
Hope this helps.
David
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10-21-2008, 08:59 PM
#8
Rennlist Member
The sensor on the top of the intake does indeed turn on the fans when the intake temperature reaches 87.5 deg Celcius. The fans also run based on several other factors including coolant temp, Frigen pressure (I love that word), and the temp switch for auto transmission.
10-21-2008, 09:03 PM
#9
Pro
Thread Starter
Bill,
Is there a air temp sensor for the mtr that is in the air stream not in the water jacket, if so, can you
tell me where it is located and how to test it.
Thank you for your help.
Is there a air temp sensor for the mtr that is in the air stream not in the water jacket, if so, can you
tell me where it is located and how to test it.
Thank you for your help.
10-21-2008, 11:05 PM
#10
Rennlist Member
It sounds like you may be thinking of the function of the MAF. It is not a temperature sensor and it is more behind the intake manifold but it is in the stream of air and measures the amount of air that enters the engine. These can indeed fail slowly and affects the drivability of the car. There have been some good threads that have covered testing the MAF.
10-21-2008, 11:41 PM
#11
Team Owner
the S4 does not have an air intake temperature sensor like the earlier car do, you might be thinking of the plug on the air filter housing I have one on my 84 Euro, this measures air temp for the intake air.
The S4 does measure the air temperature by way of the MAF this is done with a heated wire and the air cools the wire and so then the density and temperature can be figured by the MAF.
On the S4 there are 3 sensors as has been noted the one on top is part of the cooling fan circuit, the other 2 sensors are on the water bridge as Bill has noted the sensor with the Bosch connector (square ) is the Temp 2 this sends coolant temps to the LH and EZK .
the other sensor with the female plugs is for the coolant temp gauge and light. There are detailed test proceedures for testing all of these sensors in the WSM.
All that being said, what are you trying to do? what kind of problems are you having? and what was the last thing you fixed??
The S4 does measure the air temperature by way of the MAF this is done with a heated wire and the air cools the wire and so then the density and temperature can be figured by the MAF.
On the S4 there are 3 sensors as has been noted the one on top is part of the cooling fan circuit, the other 2 sensors are on the water bridge as Bill has noted the sensor with the Bosch connector (square ) is the Temp 2 this sends coolant temps to the LH and EZK .
the other sensor with the female plugs is for the coolant temp gauge and light. There are detailed test proceedures for testing all of these sensors in the WSM.
All that being said, what are you trying to do? what kind of problems are you having? and what was the last thing you fixed??
10-22-2008, 01:55 PM
#12
Pro
Thread Starter
Mrmerlin,
Thank you for the clarification, my mistake on the air temp sensor, I thought the ecu got it's info
from an air temp sensor, I didn't know it got the temp reading from the water temp. The problem
I had was, after driving it, I'd shut it off for a couple of minutes then restart it. It would restart ok
but wouldn't come up to a proper idle. It would idle around 300 to 400 then die if I didn't give it a
little gas. I've lubed the ISV and it seems to be working properly, I thought it was a problem related
to heat as it worked fine when the motor was cold. It sounded to me like a sensor was on the way out
and just acting up intermittently but maybe that's not the case. What would your guess be ?
Thanks for your input..
Joe
Thank you for the clarification, my mistake on the air temp sensor, I thought the ecu got it's info
from an air temp sensor, I didn't know it got the temp reading from the water temp. The problem
I had was, after driving it, I'd shut it off for a couple of minutes then restart it. It would restart ok
but wouldn't come up to a proper idle. It would idle around 300 to 400 then die if I didn't give it a
little gas. I've lubed the ISV and it seems to be working properly, I thought it was a problem related
to heat as it worked fine when the motor was cold. It sounded to me like a sensor was on the way out
and just acting up intermittently but maybe that's not the case. What would your guess be ?
Thanks for your input..
Joe
10-22-2008, 03:28 PM
#13
Team Owner
well with that info i would suggest,
first adding a can of techron to the fuel for a few tanks ( this is to clean out the check valve in the fuel pump and help keep the injectors working as they should) do lots of short rides instead of a X country ride it give the techron more time to work on any deposits.
Next you can check the fuel pressure regulator and dampers for being able to hold vacuum and or leaking fuel out of the vacuum ports.
If none of this cures the problems you might consider a new set of 4 hole fuel injectors , as the originals are most likley worn, See Summit racing or Five O motorsports on Ebay, IRC you need 19lb injectors, and most places dont have the correct lower O ring for the injectors , Roger also has new O rings..
This thread takes a whole different course if more info is supplied
first adding a can of techron to the fuel for a few tanks ( this is to clean out the check valve in the fuel pump and help keep the injectors working as they should) do lots of short rides instead of a X country ride it give the techron more time to work on any deposits.
Next you can check the fuel pressure regulator and dampers for being able to hold vacuum and or leaking fuel out of the vacuum ports.
If none of this cures the problems you might consider a new set of 4 hole fuel injectors , as the originals are most likley worn, See Summit racing or Five O motorsports on Ebay, IRC you need 19lb injectors, and most places dont have the correct lower O ring for the injectors , Roger also has new O rings..
This thread takes a whole different course if more info is supplied
10-22-2008, 06:35 PM
#14
Pro
Thread Starter
Mrmerlin,
I'll start with the techron & check the fuel pressure regulator and dampers and see where that gets me.
I take it you don't suspect the Temp 2 sensor on the water bridge as being a possibility ? Do I have the
wrong symptoms for that piece to be a possible cause.
Thank you for your assistance.
I'll start with the techron & check the fuel pressure regulator and dampers and see where that gets me.
I take it you don't suspect the Temp 2 sensor on the water bridge as being a possibility ? Do I have the
wrong symptoms for that piece to be a possible cause.
Thank you for your assistance.
10-22-2008, 08:53 PM
#15
Archive Gatekeeper
Rennlist Member
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Joe-
Your symptoms are a lot like mine after I did my intake R&R. Cold starts are fine, car idles right at 800 rpm. (After it warms up to normal temps (185oF at the lower rad hose), the idle inches up to 1100 rpm, I know I still have a vacuum leak under the intake somewhere.....) Recent Intake R&R, new ISV, cleaned injectors, yadda yadda.
After driving 5-200 miles, upon re-starting with a warm engine, the idle is unsteady, 400-500 rpm and stumbly, won't rev well at all, though mine won't stall. After 1-2 minutes of this, all of a sudden the idle returns to normal (~1000 rpm, as it's already warm), like someone flipped a switch somewhere. I replaced the temp II sensor on the coolant bridge to no effect.
Does your stumble go away after a minute or 2?
Your symptoms are a lot like mine after I did my intake R&R. Cold starts are fine, car idles right at 800 rpm. (After it warms up to normal temps (185oF at the lower rad hose), the idle inches up to 1100 rpm, I know I still have a vacuum leak under the intake somewhere.....) Recent Intake R&R, new ISV, cleaned injectors, yadda yadda.
After driving 5-200 miles, upon re-starting with a warm engine, the idle is unsteady, 400-500 rpm and stumbly, won't rev well at all, though mine won't stall. After 1-2 minutes of this, all of a sudden the idle returns to normal (~1000 rpm, as it's already warm), like someone flipped a switch somewhere. I replaced the temp II sensor on the coolant bridge to no effect.
Does your stumble go away after a minute or 2?
