Logging IAT2 on Roush Phase 2 Car - Possibly With OBDLink MX+?

[donlx90]

possibly a little off topic (but not really) Ive done a fair amount of research and tinkering with my inter cooling system (2018 Roush ph1 upgraded to ph2- heat exchanger & calibration) and Im convinced that the delta between IAT1 & IAT2 will ALLWAYS be more in cooler weather because I think that regardless what ambient is, the IAT2 will always climb to a certain temp.
Ive also noticed that if I drive the car for 2 hours without getting into boost, and have 120 deg IAT2's, the fluid in the Degas bottle isnt even a little bit warm. Its like the fluid doesnt get warm at all unless youre getting into boost (a lot). I am also convinced that the high IAT2's are influenced by surrounding temps. Heads, intake, blower etc.....

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[SplawnDarts]

I'm in the process of doing an experiment to clarify this, but right now it looks like the IAT2 sensor read via OBDII reads about 10 degrees high across a pretty wide range of temperatures.

This may go a long way towards explaining all the complaining about IAT2 temps on these cars - the temp sensor really isn't in units of degF. There's a conversion factor that has to be applied.

 

[Jmtoast]

I'm in the process of doing an experiment to clarify this, but right now it looks like the IAT2 sensor read via OBDII reads about 10 degrees high across a pretty wide range of temperatures.

This may go a long way towards explaining all the complaining about IAT2 temps on these cars - the temp sensor really isn't in units of degF. There's a conversion factor that has to be applied.

It would unfortunately only explain the 10 degrees. Doesn't explain the other 150 degrees you see on back to back wot pulls in the warmer climates. That would be the bottom mounted micro-dick Roush calls an intercooler.

 

[ImBetterDude]

I've got a 2015 phase 2 tuned by VMP using an nGauge. I've got no IAT harness, just what's stock with the car / kit.

What's my IAT2 reading being gauged off of, is the reading valid or useful? It's like 40 degrees over ambient when cruising around, normal?

 

[donlx90]

I've got a 2015 phase 2 tuned by VMP using an nGauge. I've got no IAT harness, just what's stock with the car / kit.

What's my IAT2 reading being gauged off of, is the reading valid or useful? It's like 40 degrees over ambient when cruising around, normal?

I believe that Roush doesnt use the IAT2 harness that the other providers/tuners require so I think that youre ok. If your IAT2's are showing 40 over ambient, its probably fairly accurate. Im not sure what part of the country you are in but you will get over 40 degree delta if youre in a cool environment. My opinion is that the IAT2 temps are going to be what they are going to be (my experience 100-120) no mater what ambient is. These temps are getting into minimal or no boost.

 

[ImBetterDude]

Im reading 120 IAT2s without harness (pre boost?) when driving super soft at 80 degrees.

 

[donlx90]

I believe that you are running 120 IAT2's while driving easy. Now do me a favor, next time you do that, and you havnt been into boost, lift your hood and twist off Roush Degas cap and either use an infrared temp gun or stick your finger in it. Im better that it feels cool to the touch which floors me. Why isnt the intercooler cooling down temps unless you get into boost????

 

[brucelinc]

The gen 2 may be different but on the 2018+ models, coolant does not flow through the degas bottle. No matter how hot the temps, the coolant in my degas bottle is either cool or barely luke warm at most. Checking the temps on piping that goes to and from the IC should show cooler piping going in and warmer coming out.

 

[donlx90]

The gen 2 may be different but on the 2018+ models, coolant does not flow through the degas bottle. No matter how hot the temps, the coolant in my degas bottle is either cool or barely luke warm at most. Checking the temps on piping that goes to and from the IC should show cooler piping going in and warmer coming out.

My Degas bottle temps correlate with my piping that goes in/out of the back of the Roush unit. My experience has been;
low to no boost - the piping and Degas are 60-80 digress (close to ambient)
beating on it, the piping and the fluid in the Degas bottle are well over 110 degrees.

 

[SplawnDarts]

I've figured out that the IAT2 sensor does actually read accurately. I was wrong about it reading high. I just didn't wait long enough for it to cool to ambient - it takes almost 48 hours for the engine to normalize to room temp. I'll test this one more time with a higher ambient temp, but for now it looks like you can trust it.

Now, I took a log of some non-spirited driving. This was in very cold conditions, 28F. The test started with a hot car with a CHT of about 150 degF.

The first thing to note is that the supercharger cooling system has closed loop control - it cools down to about 100 degF when the car is moving, and then stops and holds there even though ambient air was very cold and it could have gone lower. The second thing to note is that the SC cooling performs very poorly when the car is not moving. The only available fan is the main fan, which I'm not sure ever turned on.

 

[Jmtoast]

lol

 

[brucelinc]

Yes, temps go up when not moving and REALLY go up when you shut the engine off.

When sitting still at a stoplight on the street, it doesn't really matter....unless you plan to race a car beside you. However, at the dragstrip in the staging lanes, you can keep temps down by turning on the fans with the cruise control switch and keeping the engine running. Opening the TB by revving the engine helps keep temps lower, too.

Shutting off a hot engine raises iat2 temps drastically. Starting it brings the temps down quickly...especially if you turn on the fans and/or start moving. Iat2 can go up or down very quickly depending upon fans, vehicle movement, throttle position and just whether the car is running or not.

 

[donlx90]

I've figured out that the IAT2 sensor does actually read accurately. I was wrong about it reading high. I just didn't wait long enough for it to cool to ambient - it takes almost 48 hours for the engine to normalize to room temp. I'll test this one more time with a higher ambient temp, but for now it looks like you can trust it.

Now, I took a log of some non-spirited driving. This was in very cold conditions, 28F. The test started with a hot car with a CHT of about 150 degF.

The first thing to note is that the supercharger cooling system has closed loop control - it cools down to about 100 degF when the car is moving, and then stops and holds there even though ambient air was very cold and it could have gone lower. The second thing to note is that the SC cooling performs very poorly when the car is not moving. The only available fan is the main fan, which I'm not sure ever turned on.

you will need engine coolant temp to know if your fans came on.

 

[SplawnDarts]

Do you know what the trigger for the fans is?

Having seen what IAT looks like, it can probably be dropped. OBDLink does up to 4 PIDs at a time it looks like.

There may also be a fan on/off PID - I'll have to look.

 

[donlx90]

Do you know what the trigger for the fans is?

Having seen what IAT looks like, it can probably be dropped. OBDLink does up to 4 PIDs at a time it looks like.

There may also be a fan on/off PID - I'll have to look.

I believe that in the ambient temps the you were in today, your fan wouldn't kick on until your ECT would be 220 or so

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