SmartTorque has been around for a few years, but the latest evolution known as ST2 provides additional torque when transmission sensors detect the vehicle is on an uphill grade. Cummins will have its own PCC package for 2017 and it will be available across all truck platforms.
The 2017 version also had Cummins own Predictive Cruise Control (PCC) feature, currently available only on Paccar products. If for some reason you aren't using cruise control, the 2017 version will deliver peak torque all the way down to 975 rpm.īoth of the fuel-efficient versions of the engines I drove had the ADEPT (Advanced Dynamic Efficient Powertrain Technology) technology suite featuring SmartCoast and SmartTorque2 (ST2). Interestingly, the 2016 engine would lug - if we can still use that term (it hardly applies anymore) - down to 1,070 rpm before making a downshift on a grade, whereas the 2017 dipped down to 1,040 before giving up a gear, starting from a cruising rpm between 1,100 and 1,125. The close ratio-step between 9th and 10th is meant to keep the engine running close to its fuel-efficient sweet spot as long as possible. Clutch engagement on the Eaton side is dramatically improved over earlier versions, and slipping between the top two small-step gears was barely noticeable on modest highway grades. The 2017 version of the SmartAdvantage powertrain is as smooth and perfectly integrated as any of the vertically integrated powertrains they compete with. That downshift is no longer required, but be prepared for a treat if you decide to drop it down a gear.Įlectronically speaking, it's pretty clear that Cummins and Eaton have been spending a lot of time together in the lab and on the track.
#Cummins isx cruise control not working drivers#
With trends in engine speed drifting lower with each passing year, drivers were becoming dissatisfied with the engine brake’s performance, apparently not realizing (or forgetting) that a simple downshift would restore the massive retarding power available from a 15-liter engine. The engine brake’s performance at very low rpms was quite a surprise, and even more so in the performance version of the engine, which boasts a new and improved version of the venerable Cummins variable geometry turbocharger. In plain English, the 2017 models felt peppier, a little quicker, and smoother to respond, and generally had a firmer feel. The impact of the enhancements is subtle but noticeable. In the case of the performance version, Cummins has optimized the combustion hardware and improved what it calls the combustion recipe.
Most of the changes are electronic, but Cummins has made some physical changes to the air handling system and reduced internal parasitic drag on both models. We spent a day test driving a couple of production-intent versions of the 2017 X15 (as it's now known), and a current ISX15 for comparison.Ĭoming in 2017 are two distinct versions of the engine - one tuned for fuel economy, the other for performance. And it's still very much alive and kicking today. It survived the transition to EGR (Exhaust Gas Recirculation) and then to SCR (Selective Catalytic Reduction) aftertreatment. It was introduced in 1998, although the program that brought the engine to life began in 1994.
As engine platforms go, Cummins' ISX has to be considered slightly remarkable.
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