n/a IAT Temp question???
06-28-2013, 04:25 PM
#1
n/a IAT Temp question??? head, cam only car. Noticed while data logging that the IAT goes into the red on my hp tuners. after 10 min of stop and go "ish" traffic my IAT is 115*f. Outside temp is 87*f. coolant temps were 207*f. Is my tune off? do i need a CAI? or is this totally normal?
06-28-2013, 04:48 PM
#2
head, cam only car. Noticed while data logging that the IAT goes into the red on my hp tuners. after 10 min of stop and go "ish" traffic my IAT is 115*f. Outside temp is 87*f. coolant temps were 207*f. Is my tune off? do i need a CAI? or is this totally normal?
06-28-2013, 07:05 PM
#3
TECH Fanatic
iTrader: (5)
Join Date: Sep 2008
Location: Salem/Keizer
Posts: 1,120
Likes: 0
Received 0 Likes
on
0 Posts
The "going into the red" part is just a setting in your HPT config file gauges...you can change it. Just like Ed said, it's normal under-hood heat....but kinda grinds on ya and makes ya want to build a decent cold air box (if possible), doesn't it. 
07-01-2013, 01:28 PM
#4
TECH Addict
iTrader: (10)
Join Date: Jun 2004
Location: Commerce Twp, MI
Posts: 2,918
Likes: 0
Received 0 Likes
on
0 Posts
IMO - it's heat soak around the sensor. I don't think we get accurate IAT's when we're in stop and go traffic. I also believe it can contribute to idle/cruise quality issues. I've relocated the IAT on several cars to just in front of the air box and away from anything that tends to retain heat. As a result, those cars get a true IAT reading before the charge temp blending model figures out the change in temp through the manifold & heads, which helped clean up some issues with fueling and idle quality.
A test you can do - watch a near stock car at idle for a bit of time. As the under hood temps rise, so do the fuel trims. If the PCM is calculating air density at higher IAT's (meaning less dense air / less O2), then it'll calculate less fuel required for combustion. Problem is, the IAT is actually cooler and more dense that the PCM realizes (because of the false, heat-soaked measurements), which causes a leaner burn that is noticed by the O2 sensors. Hence, the positive fuel trims.
A test you can do - watch a near stock car at idle for a bit of time. As the under hood temps rise, so do the fuel trims. If the PCM is calculating air density at higher IAT's (meaning less dense air / less O2), then it'll calculate less fuel required for combustion. Problem is, the IAT is actually cooler and more dense that the PCM realizes (because of the false, heat-soaked measurements), which causes a leaner burn that is noticed by the O2 sensors. Hence, the positive fuel trims.
