We used to be carburetor junkies. When fuel injection started showing up on our fullsize trucks, we were in a hissy-fit about a fuel delivery system that couldn't be readily modified. Then we finally pulled our heads out of the sand and realized that fuel injection was the off-road god's gift to wheelers. Electronic fuel injection increased our fuel economy, improved the throttle response and driveability of our trucks, made hard cold starts a thing of the past, and best of all let us drive our trucks to almost any angle without starving the engine of fuel. By the late 1990's, EFI was becoming easily modifiable, and complete aftermarket fuel-injection kits were showing up, so any gripes we previously had were now unfounded.
 We chose a '79 Cherokee Chief...  We chose a '79 Cherokee Chief with a 401ci engine to be the recipient of the Howell equipment. Before starting the kit, we put the big Chief on the Dynojet dyno at Orange County Corvette in Irvine, California, to get our initial horsepower numbers. We almost felt bad bringing in a beat-up 4x4 right next to 1,000+hp Corvettes. At 168.47 hp and 238.81 lb-ft of torque, the numbers were a little lower than we expected for a built 401 V-8. |  The Howell AMC V-8 kit comes...  The Howell AMC V-8 kit comes with everything you need short of an air cleaner. The wiring harness has connectors throughout and literally plugs together with the ECU, the O2 sensor, the throttle body, the speed sensor, and the battery. Even the electric fuel pump, filter, and fuel line are given to make sure everything matches in this all-inclusive kit. |  The previous carburetor could...  The previous carburetor could never be tuned absolutely correct for the engine in all conditions, and made this Cherokee very frustrating to drive. Since this was Jeeps R Us' ride, they took care of all the work for us while we snapped the shots. |
We only have one gripe left about fuel injection: Why aren't there a ton of 50-state smog-legal EFI retrofit kits available? It seems crazy not to have Air Resource Board exemption order (EO) numbers on all these retrofit kits. Fuel injection makes an engine more emissions-friendly than a carburetor because the EFI's control module is able to take engine temperature, vacuum, exhaust readings, and other variables into account and adjust the fuel delivery accordingly. But it is a long and costly process to get EO numbers from the government, even when fully deserving of them.
We did find one company that took the time and spent the money to get EO numbers for its retrofit kits: Howell Fuel Injection sells very affordable smog-legal fuel-injection kits for not only the Jeep inline-six, but now for the AMC 304, 360, and 401ci V-8 engines as well. We couldn't wait to get our hands on a kit. And at just $1,200, this kit won't be more expensive than the vehicle we're putting it on!
 Here's what makes this kit...  Here's what makes this kit so unique, and so coveted by AMC V-8 owners. The ECU is factory GM controlled and programmed to the specs of the particular vehicle it's being installed on. Howell preprograms the ECU using your intake manifold, camshaft, and cubic displacement specifications to make a plug-n-play system that requires no tuning once installed on your vehicle. The really, really important part is that special sticker sitting on top of the ECU, and has the letters ARB EO.... This makes your EFI retrofitted engine smog legal, even in the strict state of California! |  For the smaller V-8 EFI kits,...  For the smaller V-8 EFI kits, Howell uses a factory GM throttle body to add fuel and regulate air. For the 401ci kit, however, Howell utilizes a stock-style Holley 670-cfm two-barrel unit that is capable of controlling air and fuel for the bigger engine. |  To get from either a two-barrel...  To get from either a two-barrel or four-barrel intake manifold (tell Howell when ordering the kit), you'll need to bolt on the adapter plate that allows the stock-style GM two-barrel throttle body to fit on top. The throttle body bolts right on using included bolts and gaskets. |
 The factory mechanical fuel...  The factory mechanical fuel pump will need to be removed from the engine, as you'll be using an inline electric fuel pump to deliver fuel from now on. Howell gives a block-off plate to put on the engine in place of the mechanical fuel pump. |  Instead of the mechanical...  Instead of the mechanical fuel delivery system, Howell has included an Airtex electric fuel pump and fuel filter that Larry Garcia mounted on the framerail. The smaller V-8 EFI kits will use a similar electric fuel pump, chosen specifically for the necessary output of the kit. |  Howell includes a single O2...  Howell includes a single O2 sensor (and the weld-in bung) to get readings of the exhaust back to the ECU. We know what you're thinking right now, and no, you don't have to run single exhaust to get this system to work correctly. If you have dual exhaust, it'll be OK to put the O2 sensor on either bank of cylinders. Jeeps R Us chose to put theirs near the driver-side header collector. |
 A supplied speed sensor will...  A supplied speed sensor will need to be put in between the transfer case and speedometer cable. It should fit right on, and has a two-wire connector that will need to be plugged into the Howell wiring harness. |  Once all the hardware was...  Once all the hardware was on the engine, Jeeps R Us went back and plugged all connectors on the wiring harness into their respective sensors. This entire kit could be done in a day if it weren't for having to fix five other things broken on your truck while you're installing the kit (we know how that goes) |  To finish it off, we ran the...  To finish it off, we ran the wiring harness through a hole we developed in the middle of the firewall, and pulled the ECU's side of the harness through into the cab. Jeeps R Us mounted the ECU inside the cab to keep it best protected from off-road rigors. We suggest that you do the same. |
Once we got the Howell throttle-body EFI kit on, we headed back to Orange County Corvette to get another pull on the dyno. Our horsepower numbers were still lower than expected (this was not a generous dynamometer), but we bumped from 168.47 hp and 238.81 lb-ft to 181.30 hp and 258.89 lb-ft of torque. That's a 20 lb-ft increase of usable torque for the trail!
Not only that, but the driveability and general usefulness of this Cherokee Chief were improved immensely. Jeeps R Us tells us the fuel economy has gone up 4-5 mpg since the EFI swap-a huge increase! Also gone were cold starts, stuttering, and any dying out on steep inclines.