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I've been reading a few threads regarding the lackluster performance of the factory CAC, and how particularly when towing the engine management system will retard timing and essentially reduce available power once the CAC heat soaks... Can anyone give me a ballpark IAT2 reading that this starts to happen? Or is there another way to see this via my SCTX4? I'm not a real tech savvy guy, have no idea how to data log or anything like that, but I can fumble my way through setting up the SCTX4 to watch the various gauges and sensors while I'm driving down the road. I would be very interested in seeing if/when this happens in my specific use case.
 

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2018 SCREW Platinum 3.5, BoostKing tuned.
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@Boostking told me, but it was so many emails ago I can't remember. I want to say 140*f but I can't be certain. Hopefully he will chime in.

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2019-06-14 11_07_43-Spark Retard for ACT.jpg
Timing is pulled starting at 110 charge temps. You take the function (two columns) and the temp, and multiply it against the other table based on load and RPM.

Example. Charge Temp = 110° F. RPM = 3800, load = 1.4.

So the math would be -10 x .05 = 0.5 degrees of spark removed.

As temps get hotter, the negative multiplier gets larger, and thus the amount of spark removed does the same.
 

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Is CAC temp and IAT2 the same thing on the gen2 motors Brett?

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Yes. CAC is Charge Air Cooler post temp, and IAT2 is the same thing but the generic datalogging parameter.
 

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View attachment 158794
Timing is pulled starting at 110 charge temps. You take the function (two columns) and the temp, and multiply it against the other table based on load and RPM.

Example. Charge Temp = 110° F. RPM = 3800, load = 1.4.

So the math would be -10 x .05 = 0.5 degrees of spark removed.

As temps get hotter, the negative multiplier gets larger, and thus the amount of spark removed does the same.
Amazing post!

By the way, your next post confused me regarding CAC temps/IAT2 Temps. Especially since I get a big variance in temp values between those 2 pids.

Keep in mind that my tuner is not the same brand as the one you have great expertise on. And although you would know the role the tuner (hardware) plays in interpreting the various data/signals from the odb port, I don't know if the value displayed on the screen is accurate, nor what would be the logical explanation if it wasn't. Lol

My pid called "CAC_T" is supposedly a Fahrenheit value at the CAC. But it often reads below ambient and much cooler than IAT2 Temps.

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My CAC temp gets to 120-130 without trying at all... These things need an upgrade I think

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I dont normally log both CAC and IAT2, due to them being the same. I will admit that the CAC is a DMR which is a little different data stream (direct memory read). Maybe there is a offset or delay.

Next time I'm out logging one of these vehicles, I'll log both and see what they say.

I'm not familiar with CAC_T. Could be pre intercooler temp, or in other words IAT. Not sure there.

I can say with confidence, that CAC and IAT2 always get really hot when I'm pushing these trucks during preload dev. A FMIC upgrade is a must in my opinion.
 
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Great question OP! And good info to know.
 

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I dont normally log both CAC and IAT2, due to them being the same. I will admit that the CAC is a DMR which is a little different data stream (direct memory read). Maybe there is a offset or delay.

Next time I'm out logging one of these vehicles, I'll log both and see what they say.

I'm not familiar with CAC_T. Could be pre intercooler temp, or in other words IAT. Not sure there.

I can say with confidence, that CAC and IAT2 always get really hot when I'm pushing these trucks during preload dev. A FMIC upgrade is a must in my opinion.
CAC temp is post-CAC, at the map sensor on charge pipe. There is a huge difference in temps between it, and IAT2, until the CAC heat soaks.
This is just a random screenshot from a while back. Temps are in *C.
screenshot (2).jpg
 

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You've seen my CAC temps before. No one was really able to explain the low temp readings.

I have so many pids to choose from that I should cycle through and see if there's another?

Shot below is with morning Temps while truck is warming up. Probably in the mid 70's ambient and not even out of the driveway yet. (long dirt drive)

Edit: from the pic of the cars in front, this would be leaving from the office and sitting at the first traffic signal

Ambient could very well be in the 90's



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I have that same gauge setup for IAT2 and CAC T.
The CAC temp is always lower while cruising but when I sit in traffic long enough the 2 temps always even out. Dead even.
But the second I hit the gas to move the CAC temps drop faster than the IAT2 temp.

I believe it is the only CAC option we have with the n-gauge. Unless I missed one while scrolling through the long list.
 

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I have that same gauge setup for IAT2 and CAC T.
The CAC temp is always lower while cruising but when I sit in traffic long enough the 2 temps always even out. Dead even.
But the second I hit the gas to move the CAC temps drop faster than the IAT2 temp.

I believe it is the only CAC option we have with the n-gauge. Unless I missed one while scrolling through the long list.
Sure makes you wonder.

Perhaps that pid IS the right sensor but the "equation" (function) assigned to the data stream from the odb is wrong?

You know, like it's "2 X A" when it should be 2.2 X A?

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My CAC and IAT2 does the same as Rusty's. Same if I come to a stop once warmed up, but the CAC cools off way quicker and often reads below ambient which isn't physically possible from my understanding. Using nGauge on Gen2.
 

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My CAC temp gets to 120-130 without trying at all... These things need an upgrade I think

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Right? The other day when i towed down to Bryce Canyon my IAT2 was consistently 120F even with my AFE intercooler.
 

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The CAC temp likely reads cooler because the IAT2 sensor is sitting directly on the manifold, under the engine cover.

The Sensor on my diesel Liberty is bolted to the top of the manifold under a cover as well and it will read 20F over ambient just coasting down a mountain for 5 min straight. I have my own iat sensor in the cold side intercooler tube no more than 2’ from the IAT sensor in the mani and it reads ambient in the same scenario.

In the Ecoboost, Once you get on the gas hard and it opens up the throttle body and you get a lot of air flow, it cools the manifold and sensor.

What you guys should do is put the key in when the truck is cold but dont start it and see if the two sensors are close. This is how i know my jeeps sensor is not messed up. If it reads the correct ambient temp before i start it, its right.
 

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The CAC temp likely reads cooler because the IAT2 sensor is sitting directly on the manifold, under the engine cover.

The Sensor on my diesel Liberty is bolted to the top of the manifold under a cover as well and it will read 20F over ambient just coasting down a mountain for 5 min straight. I have my own iat sensor in the cold side intercooler tube no more than 2’ from the IAT sensor in the mani and it reads ambient in the same scenario.

In the Ecoboost, Once you get on the gas hard and it opens up the throttle body and you get a lot of air flow, it cools the manifold and sensor.

What you guys should do is put the key in when the truck is cold but dont start it and see if the two sensors are close. This is how i know my jeeps sensor is not messed up. If it reads the correct ambient temp before i start it, its right.
Hasn't been run in 9 hours.
 

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Compared to the IAT2, your CAC is really small. :D

On a serious note, when I leave for work tomorrow I will try remember to check if my CAC is small or big.

In the morning the CAC was 78 and the Iat2 was 82.
Almost identical again when I left work.
 

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Hasn't been run in 9 hours.
Sounds like either one sensor is bad or the scaling in the tune is wrong. I cant believe its the tune because as far as i know, the temp sensor scalling is the same even though one may be 2.5 Bar and the other 3 bar.
 
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