Why is my embient temp reading so far off ??? - LS1GTO.com Forums

Vendors


Go Back   LS1GTO.com Forums > GTO Tech > Tech Lounge

Reply
 
Thread Tools Rate Thread
Old 11-10-2012, 11:27 PM   #1
dlively11
Registered User
 
dlively11's Avatar
 
2005 GTO Owner

Join Date: Aug 2008
Location: SLV
Posts: 1,806


Offline
Why is my embient temp reading so far off ???

Have started scanning my car and the ambient always seems to go WAY higher then actual temps. Hell drive home tonight it was still showing 88 degrees and it was 40 outside.
__________________
Very newest ride . 2005 E55 AMG / 550 whp 600 tq bolts ons only =)

Newest ride; Porsche Cayenne Turbo

New ride; 06 PBM 35K miles Maggie 112 / 2.6 pulley 9 PSI / JBA shorties / X pipe /3 inch exhaust to Magnaflows
BC coilovers / Hotchkis F/R Sway bars / Endlinks / Bushings / built A4 tranny / 2800 stall / 11.8 with 1.8x 60 ft hot lapping.

05 300C Hemi stock 14.3@98 MPH 2.2 60 ft =?(

05 GTO A4 IBM
01 GTP 3.8 turbo
  Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 11-10-2012, 11:53 PM   #2
Wang
"Keep your thoughts positive"
 
Wang's Avatar
 
2006 GTO Owner

Join Date: May 2006
Location: Censured
Posts: 9,083
Premium Member


Online
Ambient if you are using HP Tunas, is intake air temp, I am guessing.

The GTO has no real sensor for ambient temp. It has an "IAT" intake air temp reading, which can be somewhat improved upon by changing the IAT sensor to the "Omega Thermistor" or "Vector Engineering" kit.

My Gentex mirror with gompass has an actual Ambient temp sensor though. If you do it right, you can get running IATs within 6°F of ambient : and I am measuring with Omega right in front of the TB.
  Reply With Quote Quick reply to this message
Old 11-10-2012, 11:56 PM   #3
Wang
"Keep your thoughts positive"
 
Wang's Avatar
 
2006 GTO Owner

Join Date: May 2006
Location: Censured
Posts: 9,083
Premium Member


Online
But my car is stock and has no power.
  Reply With Quote Quick reply to this message
Old 11-11-2012, 04:33 AM   #4
87LC2
Dr. Mantis Toboggan
 
87LC2's Avatar
 
2006 GTO Owner

Join Date: Sep 2006
Location: Pennsyltucky
Posts: 12,988
Premium Member


Offline
Quote:
Originally Posted by dlively11...View Post
Have started scanning my car and the ambient always seems to go WAY higher then actual temps. Hell drive home tonight it was still showing 88 degrees and it was 40 outside.

Quote:
Originally Posted by Wang...View Post
Ambient if you are using HP Tunas, is intake air temp, I am guessing.

The GTO has no real sensor for ambient temp. It has an "IAT" intake air temp reading, which can be somewhat improved upon by changing the IAT sensor to the "Omega Thermistor" or "Vector Engineering" kit.

My Gentex mirror with gompass has an actual Ambient temp sensor though. If you do it right, you can get running IATs within 6°F of ambient : and I am measuring with Omega right in front of the TB.

Correct, the ambient temp is a calculated or estimated value produced by the ECU based on IAT. On a "cold" start, ambient temp is assigned IAT temp and is modified as you drive. If your ambient temp is showing 88° on a 40° day/night, your intake system sucks like the factory air box or a K&N.

I worked over a Volant intake several years ago, insulating the box and MAF and isolating the air source to lower IAT's. Before my work I had sky high ambient temps like you, after I was done, ambient temps displayed were down to around 6° above actual ambient. After I switched over to a Vararam I insulated and sealed up to the hood, my IAT's are now equal to actual ambient and my displayed ambient is 6° below actual ambient.


Cliffnotes:
Your CAI sucks hard.
__________________
The Anti-Prius™
2008 JSB/Black M6 1LT
Kooks, catless, NPP
Vararam
  Reply With Quote Quick reply to this message
Old 11-11-2012, 08:28 AM   #5
dlively11
Registered User
 
dlively11's Avatar
 
2005 GTO Owner

Join Date: Aug 2008
Location: SLV
Posts: 1,806


Offline
Quote:
Originally Posted by 87LC2...View Post
Correct, the ambient temp is a calculated or estimated value produced by the ECU based on IAT. On a "cold" start, ambient temp is assigned IAT temp and is modified as you drive. If your ambient temp is showing 88° on a 40° day/night, your intake system sucks like the factory air box or a K&N.

I worked over a Volant intake several years ago, insulating the box and MAF and isolating the air source to lower IAT's. Before my work I had sky high ambient temps like you, after I was done, ambient temps displayed were down to around 6° above actual ambient. After I switched over to a Vararam I insulated and sealed up to the hood, my IAT's are now equal to actual ambient and my displayed ambient is 6° below actual ambient.


Cliffnotes:
Your CAI sucks hard.

Well the thing is my Ambient ends up the same as my IATs typically. Working on the intake. Not so easy with the Maggie. Even with the best intake you are not getting ambient IATs with a Maggie. They produce too much heat.
  Reply With Quote Quick reply to this message
Old 11-11-2012, 08:47 AM   #6
mistermike
10-4
 
mistermike's Avatar
 
2004 GTO Owner

Join Date: Dec 2003
Location: Cleveland
Posts: 20,801
GKPW52

Offline
Try looking at ambient after the car has been sitting overnight and not getting hit with direct sunlight. It should read the same as actual temperature +- a few degrees. If not, the sensor itself might be bad, or the connector corroded.
__________________
http://i67.photobucket.com/albums/h306/MikeStainlessWorks/SigPicAniSm.gif
World's First Twin Screw Pontiac GTO

Blown H/C 408 and other stuff. Billet tires. Plasti Dip tints. Stage 3 keyboard. /////.
2008 HHR SS tweaked
2003 CTS w/ dead hooker in spacious trunk
fquick
  Reply With Quote Quick reply to this message
Old 11-11-2012, 08:55 AM   #7
dlively11
Registered User
 
dlively11's Avatar
 
2005 GTO Owner

Join Date: Aug 2008
Location: SLV
Posts: 1,806


Offline
Quote:
Originally Posted by mistermike...View Post
Try looking at ambient after the car has been sitting overnight and not getting hit with direct sunlight. It should read the same as actual temperature +- a few degrees. If not, the sensor itself might be bad, or the connector corroded.


Yes it read correctly when its cool.
  Reply With Quote Quick reply to this message
Old 11-12-2012, 07:31 AM   #8
72firebird455
Registered User
 
2005 GTO Owner

Join Date: Dec 2010
Location: Gilbertsville, PA
Posts: 113


Offline
87LC2, I have the Vararam and insulated it just like yours. When I start the IAT and ambient are the same. If I stop at a light or after 10 minutes of driving the IAT will be 5-7 degrees above ambient(readings from Aeroforce gauge). Is that the best I can do? I don't have the IATRK but I was thinking about getting a used one. I don't know what the actual ambient is when I'm driving.
__________________
Kooks LT headers, high flow cats, custom exhaust, magnaflow mufflers, Vararam intake, Pedder's bushings/strut mounts/rear springs, MGW-P short shifter, Dyno tuned by Complete Street Performance 380HP 377FT-LB
  Reply With Quote Quick reply to this message
Old 11-12-2012, 07:49 AM   #9
CoolAid
Dat Torque
 
CoolAid's Avatar
 

Join Date: Aug 2007
Location: Phoenix, Arizona
Posts: 4,543


Offline
5-7 above should be considered extremely efficient.

Stock can be as high as 40-50 above down here in the summer.

I'm 4-8 above in the summer.

Sent from an 80,000 pound truck on the Interstate.
__________________
2014 GMC Sierra 2500 HD. LML, Crew, 4x4, Standard Bed. Loaded.
-SOLD- 2006 QSM GTO. LS2/A4. Cam/Exhaust/Stall. 11.74@116, 1.61 60ft
A4 Tuning Guide
  Reply With Quote Quick reply to this message
Old 11-12-2012, 08:22 AM   #10
87LC2
Dr. Mantis Toboggan
 
87LC2's Avatar
 
2006 GTO Owner

Join Date: Sep 2006
Location: Pennsyltucky
Posts: 12,988
Premium Member


Offline
Quote:
Originally Posted by 72firebird455...View Post
87LC2, I have the Vararam and insulated it just like yours. When I start the IAT and ambient are the same. If I stop at a light or after 10 minutes of driving the IAT will be 5-7 degrees above ambient(readings from Aeroforce gauge). Is that the best I can do? I don't have the IATRK but I was thinking about getting a used one. I don't know what the actual ambient is when I'm driving.

If I stop at a light for a minute or two, my IAT's will creep up a couple degrees, a few seconds after I leave the traffic light I'm back down to ambient. When I go past a Bank with the thermometer out front, my IAT's will match the thermometer. I've been a degree below or above some bank signs, but if I'm not jammed up in traffic I'm at ambient.

Stock IAT in the MAF.

I also noticed if I'm at a light with a tail wind, the IAT's will climb a little faster, if I have a head wind, they might not climb at all during the traffic light stop.

Heavy bumper to bumper traffic will add heat faster, and following a car at cruising speed after sitting in traffic will slow cool down. When the fans kick on, they like to force air out the corners of the hood scoops and it gets drawn back into the intake. I haven't tried sealing the vararam tray gap in the scoops yet as the heat isn't that bad over all, but it is a place where radiator heat gets into the vararam tray.

I was able to get my insulated Volant down to 5-7° above ambient.



Note:
At cruising speed, the ambient temp displayed on a scan tool like the Dashhawk will default to 5-7° below IAT. So that's why my ambient displayed is lower than actual ambient. The calculated ambient value is a little lower than the measured IAT value, obviously in the programming.
  Reply With Quote Quick reply to this message
Old 11-12-2012, 09:23 AM   #11
72firebird455
Registered User
 
2005 GTO Owner

Join Date: Dec 2010
Location: Gilbertsville, PA
Posts: 113


Offline
Thanks for the help. I feel like I am obsessing over the IAT. I probably shouldn't worry about it now.
  Reply With Quote Quick reply to this message
Old 11-12-2012, 01:14 PM   #12
87LC2
Dr. Mantis Toboggan
 
87LC2's Avatar
 
2006 GTO Owner

Join Date: Sep 2006
Location: Pennsyltucky
Posts: 12,988
Premium Member


Offline
As you can see, I obsessed over my IAT's for a while.
  Reply With Quote Quick reply to this message
Old 11-12-2012, 05:58 PM   #13
72firebird455
Registered User
 
2005 GTO Owner

Join Date: Dec 2010
Location: Gilbertsville, PA
Posts: 113


Offline
I followed the temps closely on my way home from work. The IAT was the same or 2 degrees above ambient for awhile. Then the ambient temperature dropped about 4 degrees and the IAT stayed the same or down 2 degrees. The difference was 4-6 degrees for the next 1/2 hour. When I got home I measured the outside air and it was 4 degrees above what the ambient was with the aeroforce. Which means the IAT was at actual ambient or 2 degrees above.

So, it seems to me the ambient stays correct for awhile then for some reason it drops below the actual outside temperature and stays lower. I kind of think that when I start driving I got onto the highway pretty quick and kept moving for a while. Then after I stopped at a few lights the IAT changed the way it was measured and lowered itself about 4 degrees below actual outside temp.

I used to notice this before but thought it was just that outside air temp changing as I went through different areas.

So overall, I think I have the vararam insulated fairly well. I just am curious why the ambient changes when the outside temp doesn't change.
  Reply With Quote Quick reply to this message
Old 11-13-2012, 02:36 AM   #14
87LC2
Dr. Mantis Toboggan
 
87LC2's Avatar
 
2006 GTO Owner

Join Date: Sep 2006
Location: Pennsyltucky
Posts: 12,988
Premium Member


Offline
Quote:
Originally Posted by 87LC2...View Post
Note:
At cruising speed, the ambient temp displayed on a scan tool like the Dashhawk will default to 5-7° below IAT. So that's why my ambient displayed is lower than actual ambient. The calculated ambient value is a little lower than the measured IAT value, obviously in the programming.

Before I did any insulation work, the displayed ambient would be higher than actual ambient, now it is lower. Like I said, the ambient temp display is a calculated or assumed value based on IAT readings. The better your intake system works, the lower your displayed ambient will be.

With my insulated Volant, my lowest displayed ambient would be actual ambient or a degree higher. With my insulated Vararam, displayed ambient is consistently below actual ambient. I vaguely remember back to 2006 with my stock air intake and ambient was more than 10° above actual.
  Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the LS1GTO.com Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 04:55 PM.




Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ©2003-2008, LS1GTO.com
Site Banner Design ©2005-2007, Cylosoft

LS1GTO.com is not affiliated with General Motors Corp.