Budget AirBox Mod & IAT Relocation

Old 07-19-2008, 02:44 PM
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Join Date: Jul 2008
Location: Schnecksville, PA
Posts: 1,217
Year: 94 XJ
Model: Cherokee
Engine: 4.0L
Default Budget AirBox Mod & IAT Relocation

Air Box restriction:

From factory the XJ air boxes have a restriction in the outlet tube (to Throttle Body)
Removal of this restriction greatly increases the airflow to the throttle body.

Tools required: Screwdriver, pliers, rag, beverage

With the airbox lid removed, the restriction can easily be seen.

By howler_gt at 2008-07-19

By simply pulling on the inner lip with a pliers or if you have strong hands, manually.
There is some resistance as there are two o-rings on the inside.

By howler_gt at 2008-07-19

Once the restriction is removed, use your rag to clean up any residual oil or dirt that may have collected inside.

By howler_gt at 2008-07-19

IAT Relocation.
IAT (Intake Air Temperature) senses the temp of the air coming into the intake and sends this info to the ECU which adjusts the fuel accordingly.
There are several problems with its location.

1. It is located TOO far into the intake. By the time the air reaches the IAT, its temperature has increased drastically.
2. CCV oiling. The IAT is located between the CCV and the intake valves.
The vaccuum coming from the CCV is highly laden with oil vapor/fumes. This in turn causes the IAT to become blackened and give false readings.

NOTE: If you decide NOT to relocate the IAT, it IS a good idea to at the very least, remove the IAT from the intake and give a thourough cleaning. There is a diode located at the center of the sensor..it is BLUE. If you cannot tell what color it is...CLEAN IT.
Clean IAT:

By howler_gt at 2008-07-19

Intake Layout:

By Howler_GT at 2008-07-19

Tools/ supplies required:
19MM ope3n-end wrench
1/2" pipe plug (thread sealer optional)
Drill (cordless is best),
1/2" drill bit (step-drill is best)
Wire cutters
Electrical tape
(2) 3' long 20ga wires. Different colors
Black wiring conduit (Or whatever color you like best)

Disconnect the IAT from its wires.
Use 19MM wrench to carefully remove the IAT from the intake.
CLEAN IT. If it is TOO ugly looking or you were NOT careful when removing it replace it.
1/2" pipe plug should make quick work of the gaping hole left in the intake.

The airbox LID is a perfect location. Oil-free, filtered and far away from the HOT engine.

If you haven't already done so...clean the airbox lid. Nothing worse then getting greasy fingerprints over your nice new mod.

Locate a good mounting location. we chose right next to the snorkel, just high enough to clear the airbox lid mounting clips.
Drill a 1/2" hole for the IAT.

By howler_gt at 2008-07-19

By howler_gt at 2008-07-19

No need to do any threading.
Just make sure there are no pieces of leftover plastic that can be sucked into the intake.
BY HAND: Thread the IAT into this hole. Don't worry, the metal of the IAT will make its own threads in the soft plastic. Thread it all the way until the main body of the IAT contacts the lid.
Side note: Rotate the IAT so the clips for the wire connector are on TOP. You will thank yourself later for this.

What it will look like:

By howler_gt at 2008-07-19

By howler_gt at 2008-07-19

From inside:

By howler_gt at 2008-07-19

Install the airbox lid. Wait!!! Did you at least check your air filter?
Heck, you're THERE...
Install the air box lid. And connect any hoses that you may have removed.

By howler_gt at 2008-07-19

Now all thats left is the wiring.
Whoops..Its way TOO short to reach.
Clip the connector off the wiring harness. I just clip the exposed wires in half. Leaves enough on both the harness and connector to splice to.

WIRE COLORS: IAT sensor has two wires that need to be spliced.
(1) Red/Black
(1) Blue/Black
Be sure to orient the splice wires accordingly.

Helpful Tip: I chuck the splice wires in my cordless drill and spiral them together. This makes for insertion into the new wire loom (conduit) a whole heck of a lot easier.

Reconnect the newly spliced wires to your newly relocated IAT.

Clean yourself up. Put away your tools (or at least remove them from your engine compartment.

Fire it up and take it for a spin.
Notice anything?
If not at first...your gas gauge will.

WE noted a 1-1 1/2 MPG increase.

Total cost of ALL MODS: Less than $10 (w/o new IAT)


Last edited by Howler_GT; 08-09-2008 at 10:10 AM.
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