Our '08 diesel-powered Jeep Grand Cherokee has racked up more than 40,000 miles since we picked it up in Detroit back in 2007 ("Detroit To L.A. In Three Days," Feb. '08). Since that time we've use the truck to test four sets of tires, develop a new shock package with Bilstein, test MBRP's DPF-back exhaust, and prototype a new air intake with S&B Filters. For the last three months, we've been collecting fuel economy data with a TS Performance MP-8 Luxury Edition computer module on the Jeep-and the results have been impressive.
Installation
TS Performance engineered the MP-8 Luxury Edition computer module for the new crop of diesel-powered Mercedes cars and SUVs that feature the 3.0L V-6 diesel engine. When we mentioned we had a Jeep with the same 3.0L diesel, TS asked us to try out an early version of its module that was intended to increase fuel economy and add a small power boost.
The installation was as easy as it gets. The MP-8 used the same connectors as the Bosch high-pressure common-rail system. With the engine cover removed, we plugged the module into the rail-pressure sensor and connected the other side of the MP-8 harness to the factory wiring. Then we used zip ties to fasten the module to the suspension's shock tower brace and keep it as far away from the heat of the turbo as we could get.
Power
When we fired the Jeep up, the engine idled as if it were stock, yet the throttle response felt instantly better. There was an increase in power across the entire rpm range, and the MP-8 added enough torque that we were able to climb grades that had previously required the transmission to downshift.
Still, with its conservative fuel calibration, we saw the MP-8 Luxury Edition module add more than 10 hp and 30 lb-ft of torque at the wheels.
Fuel Economy
How can a module add power and fuel economy? By recalibrating the fuel injection event and pressure, the MP-8 not only increased the Jeep's power, but throughout the 10,000 miles of driving, our average fuel economy went from 14.8 to 16.9. On long highway trips we now average 20 mpg.
 The TS Performance MP-8 Luxury...  The TS Performance MP-8 Luxury Edition computer module was designed for the new, diesel-powered Mercedes vehicles. But in our experience, it will also work for Dodge Sprinter vans and Jeep Grand Cherokees with the 3.0L Mercedes diesel engine. Installing the MP-8 was a simple plug-in process that instantly gave our '08 Jeep more than 10 hp, 30 lb-ft of torque, and a 2-to-6-mpg increase in fuel economy. |  The MP-8 plugs into the vehicle...  The MP-8 plugs into the vehicle between the rail-pressure sensor (labeled here as: Sensor-Fuel Pressure) and the factory wiring harness. We zip tied the module to the strut tower brace that goes over the engine and routed the wiring harness away from the heat of the turbo. | |