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A lot of people keep saying they see a 10 degree difference between ambient and charge air temps with the same FMIC I have. (CPE Lightweight) I don't see this at all. It's been more like 20-30 driving around the street. Is this normal or is something up?
 

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2018 Ford Focus ST1
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465 Posts
Are you using Torque Pro to keep track of your temps? If you check the ambient temp sensor what does it say? After the car has sat for a night the ambient and CAT values should be virtually identical (<1 degree), so you may need to do like some of us have done and modify your CAT equation in Torque Pro. My equation is ((((Signed(A)*256)+B)/64)*1.8+32)-12. Some guys on here have used anywhere between -16 and -10 or so on the end of the equation because of variances in the sensors. Either way, before you start the car in the morning, the CAT and Ambient Temp values should be the same. If not, and it's like mine was and showed about 12-13 degrees hotter with the aftermarket intercooler (was 16 different with stock unit, strangely), then just update the equation.
 

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2014 Focus ST ST3.
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293 Posts
This has been up before. The guys at stratified say this is normal on facelift cars. Your readings may be off. But in actuality it's running perfect and nothing to worry about. Search around. There is a thread on this.
 

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2014 Focus ST ST3.
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293 Posts
So is the solution to bring it up to my tuner?
Yes you should. Get a log and send it. I believe it can be compensated for and corrected via new map.
 

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Ok after 15 they changed an equation with the map sensor. Which caused the charge temp readings on the facelift models to read anywhere from 10 over in boost up to 30 over in idle or cruise. I have talked to Ryan Martin at Purple Drank tuning over this for hours. He doesn't like to mess with the numbers in the ecu with that sensor because if you don't get it exactly right, your ecu uses some of the temp data for its safety protocols and if they are off at all well I don't need to explain that to you. If you want to know what your charge temp really is, if you have your ambient temp on and then instead of having charge air temp as one of your PIDs, select intake compressor temp or turbo intake compressor temp, this is your charge temp right before or around entering your turbo. If you notice its usually a few degrees above ambient, because its actually your true charge temp. Yes I know that Alex or Bugasu at Strat did figure out which numbers to change to supposedly get the sensor on the facelifts to read what they should, but from what I understand most tuners don't mess with or change it. Also this is one of the main things, AIR TO AIR INTERCOOLERZ ARE NOT 100% EFFICIENT THEY ARENT EVEN 90% EFFICIENT. SO people who tell you they are seeing 2 degrees over amibent and crap like that or even in boost they'll see 5 degrees under amibent, cool but its not happening, not really your car is seeing it like that but your car isn't actually cooling the air down to below ambient because thermal convection and transfer within an air to air intercooler isn't efficient enough to give those kind of reduction in temperatures. Point being, your intercooler and ecu and everything else is working exactly as it should.
 
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