Tuner gurus: Air temp sensor location? - ZR-1 Net Registry Forums

Paul Workman · 03-09-2012

I have heard/read about and seen a few air temp sensors relocated closer to the filter.

Question:

If one is adjusting the tune by dyno results, is there any andvantage to moving the sensor? I think not, as it is handled in the tune. And I don't see how being a foot closer to the air filter at WOT is going to make any difference. I mean, what is the air temperature delta at two points a foot or so apart, measuring the same air column moving at huricane speeds???

P.

1990 quasar blue · 03-09-2012

Quote:

Originally Posted by Paul Workman

I have heard/read about and seen a few air temp sensors relocated closer to the filter.

Question:

If one is adjusting the tune by dyno results, is there any andvantage to moving the sensor? I think not, as it is handled in the tune. And I don't see how being a foot closer to the air filter at WOT is going to make any difference. I mean, what is the air temperature delta at two points a foot or so apart, measuring the same air column moving at huricane speeds???

P.

Great question. I was wondering the same thing. I had it relocated but removed it when I installed my HAT chip since that's supposed to address the situation. I just saw it last night and thought hmmmmm I wonder.

mike100 · 03-09-2012

I plugged my original unit back into the harness (the one in the air horn) and it was (TECH1 scanner) reading a LOT warmer than the true ambient- which my relocated IAT reads.

The manifold gets heat saturated and I'm not sure why the IAT doesn't measure reasonable air temps more than it reads the hot manifold aluminum. seems like some newer car designs have IAT's in plastic or rubber intake duct sections.

GOLDCYLON · 03-09-2012

Quote:

Originally Posted by mike100

I plugged my original unit back into the harness (the one in the air horn) and it was (TECH1 scanner) reading a LOT warmer than the true ambient- which my relocated IAT reads.

The manifold gets heat saturated and I'm not sure why the IAT doesn't measure reasonable air temps more than it reads the hot manifold aluminum. seems like some newer car designs have IAT's in plastic or rubber intake duct sections.

I think there is a lot of reasoning behind this conclusion. M Haibeck sold a lot of these relocator kits back in the day as well. Unless you have a before or after dyno its anybodies guess.

bdw18_123 · 03-09-2012

Quote:

Originally Posted by mike100

The manifold gets heat saturated...

That's what I'm thinking too.

It isn't that the air 2 feet away is so much different, I think it is more to do with the metal in the air-horn getting heated up from the plenum/engine getting hot which then transfers to the body of the sensor and then to the actual sensor element that reads the temp of the air passing over it.

So, relocating the IAT sensor more forward away from the heat of the engine results in the sensor getting a more accurate reading of the actual temp of the air going into the engine.

Makes sense to me, but I'm no physicist or engineer.

XfireZ51 · 03-09-2012

Moving the Manifold Air Temp sensor to the filter actually re-purposes it as an
Intake Air Temp sensor. Without modifying the calibration, the lower air temps being reported causes the ECM to richen the AFR. There are different values that should be used when the MAT is moved. I'll post a pic of the table that should be adjusted. Trying to find out what the new values should be.

gbmidyear66 · 03-10-2012

Quote:

Originally Posted by XfireZ51

Moving the Manifold Air Temp sensor to the filter actually re-purposes it as an
Intake Air Temp sensor. Without modifying the calibration, the lower air temps being reported causes the ECM to richen the AFR. There are different values that should be used when the MAT is moved. I'll post a pic of the table that should be adjusted. Trying to find out what the new values should be.

Interesting - this would seem to mean that the AFR conditions should also be changed when one blocks the coolant flow though the TB/Plenum (like I just did). I notice the Plenum/TB is much cooler now - as is the adjacent airhorn and IAT.

Paul Workman · 03-10-2012

Quote:

Originally Posted by XfireZ51

Moving the Manifold Air Temp sensor to the filter actually re-purposes it as an Intake Air Temp sensor. Without modifying the calibration, the lower air temps being reported causes the ECM to richen the AFR. There are different values that should be used when the MAT is moved. I'll post a pic of the table that should be adjusted. Trying to find out what the new values should be.

Thanks for verifying that, Dom.

Quote:

Originally Posted by gbmidyear66

Interesting - this would seem to mean that the AFR conditions should also be changed when one blocks the coolant flow though the TB/Plenum (like I just did). I notice the Plenum/TB is much cooler now - as is the adjacent airhorn and IAT.

Hey, gbmidyear66, you bring up a good point.

Mike100 said he saw a significant difference in MAT readings when comparing the mount locations; at the air horn and in the tube leading from the air filter. And, therefore, apparently the temp of the material the sensor is mounted on compromises the MAT reading accuracy.

That being the case, then logically it would make a lot of sense to isolate the sensor from heat being conducted from the engine. Bypassing the TB coolant has a huge affect on the temp of the TB and the plenum - perhaps negating the need to move the MAT to the filter area...perhaps. However the benefit to the DIS module running cooler is reason enough alone to bypass the TB; stabilizing the MAT temp is just a nice bonus!

In any case, I suppose moving the MAT is the best way to minimize conducted engine heat. But, to keep from compromising the TUNE, one would want to do that before putting out the $$ to dyno tune.

Marc tuned my car with the sensor in the air horn and the TB bypassed. Because (in part) the TB/air horn temp is reduced significantly, I suspect the temp difference that might result from relocating it is reduced "a lot", especially at WOT. So, I'm not moving mine - at least not until I find a need to return to the dyno again. But, it would be interesting to know what if any advantage there really would be by relocating the sensor vs. leaving it where it is and bypassing the TB.

p.

03-09-2012	#1
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Tuner gurus: Air temp sensor location? I have heard/read about and seen a few air temp sensors relocated closer to the filter. Question: If one is adjusting the tune by dyno results, is there any andvantage to moving the sensor? I think not, as it is handled in the tune. And I don't see how being a foot closer to the air filter at WOT is going to make any difference. I mean, what is the air temperature delta at two points a foot or so apart, measuring the same air column moving at huricane speeds??? P.

03-09-2012	#3
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: Tuner gurus: Air temp sensor location? I plugged my original unit back into the harness (the one in the air horn) and it was (TECH1 scanner) reading a LOT warmer than the true ambient- which my relocated IAT reads. The manifold gets heat saturated and I'm not sure why the IAT doesn't measure reasonable air temps more than it reads the hot manifold aluminum. seems like some newer car designs have IAT's in plastic or rubber intake duct sections.

03-09-2012	#6
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,683	Re: Tuner gurus: Air temp sensor location? Moving the Manifold Air Temp sensor to the filter actually re-purposes it as an Intake Air Temp sensor. Without modifying the calibration, the lower air temps being reported causes the ECM to richen the AFR. There are different values that should be used when the MAT is moved. I'll post a pic of the table that should be adjusted. Trying to find out what the new values should be.