Cold air intake increase MPGs in Jeeps?

[Overland Shark]

If you add a cold air intake, does that positively impact MPGs? I know you pick up a few ponies, but what about fuel efficiency?

 

[smritte]

Regardless what is claimed, its based on how the intake is configured.
The short answer is no. The long answer is, it depends.
How MPG is effected, is based on efficiency. Power gain is good, power loss is not. You can also open a can of worms with a cold air.

Here's how the intake system works. First, you need some math.
10 degrees=1%. For every 10 degrees I change air temp, power will change by 1%.

Lets take my 04 TJ.
Jeep decided to pull the air from inside the engine compartment, next to the radiator (Yep. TY jeep). Here's the test I did.

I installed a temp sensor just after the air filter.
Very low speed canyon (2mph?)
100 degree outside temp.
I was measuring close to 290 degrees inside the air cleaner. That means almost 20% power loss at low speed.
70mph (on the way home) I was 150 (ish), 5% power loss.
Custom aircleaner and pulled air from the cowl, I was at whatever ambient was. No loss (no gain either).

The reason I really didn't notice any power difference was, the way the intake manifold was designed, The exhaust manifold being under the intake, heated the air just before it went into the head. (TY again Jeep)

Is the cold air intake made of metal? Hope not. Under hood air temp will heat the "cold air" tube. Your now heating the air going in. Stock is plastic for a reason.

Next, is my air cleaner restricting me? Get an air cleaner restriction gauge and install it in your air box past your air cleaner.
Odds are your not restricting with a modern air cleaner. This is a good way to keep on top of your aircleaner anyway.

Does the cold air intake have a nice cleanable air cleaner? Almost all cleanable air cleaners (K&N, UNI..) are literal screen doors. The amount of silt that goes through is high. They compromise clean for higher flow. Do you need higher flow? Get a restriction gauge. Do you need more dirt in your engine? get a high flow air cleaner. If you have your oil analyzed, you will see how much dirt gets past your air cleaner.

I'm not going to go into velocity and air temp, We wont notice the difference.

lastly (I promise). Depending on the engine type, you can actually screw up your torque curve with one. I have two floor dyno's at work. We would do comparisons on diffrent cars with them. It would either make no difference of flatten the middle of the torque curve. All of them were louder though. I guess that means something?
The custom intake I made for my TJ never got put on the dyno.

As you can see, a few will give you slight to no gain and most will make it worse.