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Thread: CAC vs Fuel temp for SOTF 6.7L tuning

  1. #1
    Advanced Tuner JaegerWrenching's Avatar
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    CAC vs Fuel temp for SOTF 6.7L tuning

    I'm curious which one you guys use and why? I see the CAC as the better option as of now because i think you can chose your configs based on charge air temp thus allowing complete fuel and timing maps to be switched vs just limiting torque or fuel amount on the fuel temp style. I'll be doing some experimenting shortly and ill let you guys know what works best. Currently i have a fully functional SOTF fuel temp switch i've been using but i'm thinking about switching to a CAC setup.

  2. #2
    Quote Originally Posted by JaegerWrenching View Post
    I'm curious which one you guys use and why? I see the CAC as the better option as of now because i think you can chose your configs based on charge air temp thus allowing complete fuel and timing maps to be switched vs just limiting torque or fuel amount on the fuel temp style. I'll be doing some experimenting shortly and ill let you guys know what works best. Currently i have a fully functional SOTF fuel temp switch i've been using but i'm thinking about switching to a CAC setup.
    The issue I see with this is certain configs limit what injection events are active. Config 1 allows both pilots, 2 allows just pilot 1, config 3 allows only main, and 4 allows all injections

  3. #3
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by CKrueg View Post
    The issue I see with this is certain configs limit what injection events are active. Config 1 allows both pilots, 2 allows just pilot 1, config 3 allows only main, and 4 allows all injections
    I think you can change the number of injections allowed in each of the configs, definitely not defined in HPT though.

  4. #4
    Quote Originally Posted by JaegerWrenching View Post
    I think you can change the number of injections allowed in each of the configs, definitely not defined in HPT though.
    I've been doing a lot of looking through the hex and trying to figure out exactly how those tables work. Some of the injection quantity maps are only 2x2 on those other configs. I'm sure theres some way to change that but I don't know how.

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    why would you want to change the number of injections? just limit your torque output for cac temp. and done. CAC temp is easier to adjust for tuning and you dont have to worry about codes.

  6. #6
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by Powerstrokecustoms View Post
    why would you want to change the number of injections? just limit your torque output for cac temp. and done. CAC temp is easier to adjust for tuning and you dont have to worry about codes.
    Well if you had a config that only allowed one injection event or main only maybe you'd want to change it to have pilot also, or maybe you use that specific main only config for a specific tune type... Also you increase your tunes resolution by being able to have tunes separated by a completely different map with config SOTF. It's like asking why do dodge tuners utilize completely different maps based on their SOTF baro connector? Each of their switch positions is a different map for fuel and timing completely. I personally like the idea of having a tune that is dead nuts on for a specific fuel amount and ramps in smoothly vs having to limit a single tune to a specific fuel amount, essentially riding a torque limiter through the RPM range isn't ideal IMO. IT works but it's kinda crude IMO. How is CAC easier for adjusting when compared to Fuel temp? They both use a torque to fuel amount limitation based on a sensor's voltage, you do have more maps to change for fuel temp vs CAC and i see that as a negative also one more code to change, is there anything else I'm missing?

  7. #7
    Quote Originally Posted by JaegerWrenching View Post
    Well if you had a config that only allowed one injection event or main only maybe you'd want to change it to have pilot also, or maybe you use that specific main only config for a specific tune type... Also you increase your tunes resolution by being able to have tunes separated by a completely different map with config SOTF. It's like asking why do dodge tuners utilize completely different maps based on their SOTF baro connector? Each of their switch positions is a different map for fuel and timing completely. I personally like the idea of having a tune that is dead nuts on for a specific fuel amount and ramps in smoothly vs having to limit a single tune to a specific fuel amount, essentially riding a torque limiter through the RPM range isn't ideal IMO. IT works but it's kinda crude IMO. How is CAC easier for adjusting when compared to Fuel temp? They both use a torque to fuel amount limitation based on a sensor's voltage, you do have more maps to change for fuel temp vs CAC and i see that as a negative also one more code to change, is there anything else I'm missing?
    Exactly, config 3 normally only allows for main injection. Config 2 doesn't allow for pilot 2. The torque limit sotf does good for power however having separate tunes that used their own timing, rail pressure, boost etc would be better. Current switching is just limiting the torque but the maps are all the same between power levels.

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    Some 6.7's use a combined fuel temp and pressure sensor. some have fuel temp and fuel pressure separate. so you would have to unplug that and tap into the fuel temp wires for your switch. I have both fuel temp and cac temp tunes for sct and hp tuner.. when you do fuel temp you have to kill codes for fuel pressure.. if you ever have a fuel pressure issue, you'll never know until its too late.. for both tunes I use either fuel temp transfer function or cac temp transfer function.. i have noticed that you can do more in hp tuner when it comes to tuning 6.7's then sct.. and in sct i do have the highest level.. im constantly on the phone with them adding more and more stuff to it so i can have more tuning options. for instance the 6.7 tuning in sct does have cac transfer switch for temp. you can modify that but when you go to diesel limiter there's nothing there to actually control it.. In hp tuner its there. Using cac temp for is alot easier.. and on both tunes Ive changed a lot.. I've spent many dyno hrs.. I've also had access to other tuners across the country that do sct and hp tune files for 6.7's, i only know of about 4 people that actually have binary files.. basically just take a race file and limit your torque output for cac temp.. it will also modify the fueling because it wont let the truck put out more than what is limited on the switch.. it wont matter what your timing and configs are set to for each position. On 6.4 i use fuel temp.. but i still have to kill the code for fuel temp high because the level 5 position is .02 volts and the truck thinks its an open circuit..

  9. #9
    Quote Originally Posted by CKrueg View Post
    I've been doing a lot of looking through the hex and trying to figure out exactly how those tables work. Some of the injection quantity maps are only 2x2 on those other configs. I'm sure theres some way to change that but I don't know how.

  10. #10
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    sotf on any powerstoke besides 7.3 is pointless. use your foot as the switch

  11. #11
    Tuner JnJSpdShop's Avatar
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    Quote Originally Posted by Powerstrokecustoms View Post
    why would you want to change the number of injections? just limit your torque output for cac temp. and done. CAC temp is easier to adjust for tuning and you dont have to worry about codes.
    Any idea on what the correct switches are to use? I called Fish Tuning and they have 2 plug & play switches available for the 6.7L Powerstroke. I guess the difference is resistance and one swtich has OPEN position 1 and the other switch is CLOSED on position 1

    Western New York's Performance Headquarters

    716.830.0506




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    you can get them on amazon.. doesnt really matter. its all how you tune the truck.