Deep Breaths

Sometimes when we customize parts of our Jeeps, we unintentionally create more work for ourselves. Case-in-point: my dual battery system. In order for me to mount the battery on the driver side, I had to eliminate the factory air filter box.

Now I could have put a pipe and a filter on the factory intake hose and shoved it behind the battery, but I had other plans. I reached out to Trail Head Off Road and picked up one of their Cowl Intake Systems for the Jeep Cherokee.

The only problem is the kit is made for the H.O. series engines. The H.O. Throttle Body has a lip on it for mounting the 2 1/2″ portion of the silicone elbow. My Renix Throttle Body is a flat, flange mount; this introduced a problem.

I didn’t want to convert my throttle body to an H.O. style, so customizing was the only option. I found a throttle body adapter, made by Spectre, that bolts to the factory throttle body and gives you a lip for mounting with a hose clamp.

Now part of the problem was solved, BUT now I created a new problem. The THOR Intake System comes with a 2.5″ to 3″ reducing elbow for the intake tube, but the Spectre adaptor lip is a 3″ pipe. As anticipated, time to customize some more. I picked up a 3″ silicone turbo elbow and another 3.5″ hose clamp.

The ends were too tall to let the hood clear the intake pipe when it was closed, so I had to cut off 1 1/4″ from each side of the elbow to correct the clearance problem. Now that the clearance and adapter problem was addressed, it was time to move on with the upgrade. I place the bracket THOR sends with the kit on the firewall and traced a rough outline of it.

I used a cutoff wheel to remove the section of the cowl that the filter is going to be housed in.

After test fitting the filter, there was some additional material that needed to be removed in order to properly fit the filter inside.

At that point the filter fit properly, I installed the mounting bracket on the intake tube along with the filter and pre-filter.

I installed the system into the cowl and secured the mounting bracket. The bracket needed a little tweaking to sit flush, but it turned out great.

While I was upgrading things under the hood, I figured it was a good time to add a little more power to the old 4.0. I got in touch with Jeff at and picked up one of his 60mm Renix Throttle body’s.

I will say, the precision in Jeff’s work is of the highest quality. It’s not a polished, brand new throttle body, but everything works. If you want custom powder coating, he can have it done for you before he ships it out for an additional cost. Below is a comparison of the two throttle bodies. You can see a significant difference between the stock throttle body (Left) and Stroked Jeeps throttle body (Right).

I purchased a new Throttle Position Sensor just for my own peace of mind. I installed the TPS, Idle Air Control Valve and the Intake adaptor then bolted the new throttle body to the intake manifold.

I hooked up my scanner and adjusted my TPS to 17%.

I double checked the transmission side of the TPS to ensure it was adjusted to 83% of its reference voltage to ensure proper shifting while driving. The formula for setting the transmission side of the TPS is:

Reference Voltage X .83 = Adjustment Voltage.

I used push pins to probe the wires going to the connector. (You can also back probe the connector if you want, but the connectors are WeatherPack connectors and you take the chance of tearing the insulation boot on the back of the connector.) My reference voltage was 4.684 Volts DC. Using the formula, I needed to be as close to 3.887 Volts DC as possible, which I was actually spot on when I checked it.

Now that all the adjustments and linkage were hooked back up, I installed the silicone elbow that I modified and clamped everything down. I cut the stock breather tube and installed it onto the intake system.

All in all, the system needed some modifications to make it work on a Renix era Cherokee, but nothings impossible. That being said, the clean and simple design of THOR’s was a great addition. Be sure to check out for there awesome Cowl Intake Systems and if you’re looking to upgrade your Renix Throttle Body.