Remember the ’07 and ’08 Jeep Grand Cherokee CRD with the 3.0L Mercedes V-6 under the hood? Don’t be alarmed if you can’t. Like the ’05 to ’06 diesel-powered Jeep Libertys, Chrysler didn’t make a large production run of Grand CRDs, and many people quickly forgot about them once the diesel option was hacked after two model years. Still, oil-burning Grands can be spotted here and there throughout the country.
| All dyno testing was performed on Calibrated Power Solutions’ custom-built, all-wheel-drive MD-500 load-cell Mustang chassis dynamometer. Each test was run in the same manner as well: a 7-second sweep (from 2,500 rpm to 4,200 rpm), starting with the Jeep under power, the transmission in Fourth gear, and with the torque converter locked. All dyno numbers are uncorrected.
Torquey but Thirsty
Although the Mercedes engine’s underrated power and torque output in the Grand Cherokee was a nice surprise, in our minds they always seemed a bit sluggish. Add in the fact that overall fuel economy was a slight letdown, and the midsize SUV left a lot to be desired. In stock form, most ’07 to ’08 CRD owners typically see their mileage range from 20 to 24 mpg on the highway and hover in the mid to upper teens around town.
| Rated at 215 hp and 376 lb-ft from the factory, the DOHC, 24-valve 3.0L V-6 from Mercedes provides ample motivation for a 4,800-pound Jeep Grand Cherokee, but we’ve always felt it could use a little more oomph. Luckily, Nick Priegnitz of Calibrated Power Solutions was able to extract more power and mileage from this mill without ever having to remove the plastic engine shroud.
50 hp and 2 to 3 mpg
Enter Calibrated Power Solutions, a company that has a knack for creating more powerful and fuel-efficient calibrations for today’s common-rail engines. After spending some time dyno-tuning an ’08 test mule, they crafted a fuel economy tune that was good for a 20hp and 75-lb-ft gain, and a performance file that added nearly 50 hp and 90 lb-ft to the Grand’s repertoire. In the months following this testing, the Jeep picked up 2 to 3 mpg across the board (city and highway, combined) and, in the process, felt more like a hot rod than a Jeep. Perhaps most important, given the times we’re living in: all of these gains were made with the original emissions equipment left alone (EGR, DPF).
| Calibrated Power Solutions’ SPADE programmer is used to tune the Jeep, and the handheld device allows you to interface with the ECU via the OBD-II port. The SPADE will hold two modified files, as well as the original, and retails for $750. It’s also used to tune Sprinter Vans with the same engine, and the 3.2L CDI engine found in the E320 Mercedes-Benz.
2- to 3-mpg Gain
After running the Hot tune for several months, the owner claimed to see a handcalculated 2- to 3-mpg improvement across the board (on winter blend fuel, to boot), less downshifting when climbing hills and, of course, a lot more passing power. According to our calculations, the added horsepower and torque would take a full 1.5 seconds off the Jeep’s quarter-mile time (published as 16.2 seconds in stock form). Essentially, what you get is an SUV that can keep up with gas V-8s and get twice the fuel economy. Take that, Hemi Grand Cherokees!
| So far, gains of nearly 40 hp and 60 lb-ft of torque at the wheels have been realized while tuning an E320 Mercedes-Benz. That’s good enough to knock a full second off the luxury sedan’s quarter-mile sprint, and if you can keep your foot out of it, 30 mpg could likely be observed in mixed city and highway driving.
