The Jeep 4.0L
six cylinder has been a popular engine for years, and a reliable
power plant for Wranglers, Cherokees and Grand Cherokees, but it
would be nice if the naturally-aspirated 4.0 had a little more
zip. Now there’s a way to gain a 15% increase in horsepower
with the Edge Trail Jammer.
Well-known for their diesel-performance products, Edge Products in Ogden, Utah, has applied their air/fuel and electronics expertise
to Jeeps. The company offers the new Trail Jammer system for
1997 to 2004 Wranglers and Cherokees that have the fuel-injected
4.0L straight-six engine. A kit to fit the 2005 and 2006 models
is on the way.
new Trail Jammer system comes complete with all necessary
parts for the simple installation.
Trail Jammer’s (top) high performance filter
flows 97% better than stock, (195 cfm compared to the
OEM 99 cfm).
We recently had the opportunity to test the Trail Jammer on
three vehicles. The first was a 2000 TJ Wrangler Sport with a 5-speed
manual transmission. The Jeep was bone stock except for a set
of BFGoodrich 31 x 10.50R15 Trail T/As, which are slightly larger
than the original 30 x 9.50 rubber. Running the Wrangler on the
dyno showed a baseline rear-wheel output of 156HP and 202 ft-lbs
In addition to highway
performance, we were interested in how the Edge kit would affect
the idle and throttle response in low
range rockcrawling. For this purpose we borrowed Jason Antonucci
and his 2003 Wrangler Rubicon, which also was equipped with a
manual tranny. Jason is an experienced four-wheeler with a passion
for difficult trails like The Hammers in Johnson Valley and the
Rubicon, or you might find him playing around Cougar Buttes.
He also has a custom rock buggy built by Rock Equipment that
sports Unimog axles with an Atlas transfercase, and an ’89
Wrangler with an Atlas box and coil-over suspension. While the
2003 Rubicon we used for our test sees its share of wheeling,
it’s also a daily driver. It was running 35 x 12.50 R16
Goodyear MT/R tires and a Rubicon Express Long Arm 5 1/2” lift
The third installation was on a '97 TJ Sahara with 31 x 10.50 R15 BFGoodrich Mud Terrains. This Jeep was not used in dyno testing but was used for photography and seat-of-pants response evaluation.
Shawn Maxey at Browns
Valley RV Performance Center in Browns Valley, California,
walked us through the simple installation.
The Trail Jammer kit includes three main components: a throttle
body, an electronic module and a cold-air intake system. Edge’s
high-flow throttle body with a 62mm bore accommodates increased
airflow and improves overall driveability. The Edge Trail Jammer
Electronic Module optimizes fueling between the Jeep’s
PCM and the 4.0L engine on-the-fly. This black box uses a factory-style
harness to plug into engine sensors under the hood. Air enters
through the Trail Jammer’s cold-air intake (built by AFE),
which flows 97% better than stock, (195 cfm compared to the OEM
99 cfm). The system’s oil-impregnated, cotton-mesh filter
traps dirt and debris, and is washable & reusable.
Edge Products, the Trail Jammer performance kit has been designed
so that even the non-experienced owner can install
it in about an hour, with very minimal tools. After disconnecting
the throttle body and removing the four bolts, Shawn lifted it
off the intake manifold. Then it was simply a matter of moving
the throttle position sensor, the idle control valve, and the
MAP (manifold absolute pressure) sensor, all attached with a
couple of screws, to the new Edge throttle body, which was then
reinstalled on the intake manifold using the original gasket.
The two sensors, throttle cable, and return spring were reattached.
Edge’s high-flow throttle body
(right) with a 62mm bore accommodates increased airflow
derivability compared to the stock (left) 60mm.
The MAP (Manifold Absolute Pressure) sensor was moved
over to the new throttle body.
idle controller was moved over using a small Torx bit driver. |
Completed Edge throttle body assembly.
Note: swapping the idle control box requires a Torx screwdriver.
In addition, early model TJ’s have
a secure Torx bolt, which will require a special bit. Craftsman
Tools offers a secure bit set which includes a range of bits
including the one needed for this task)