Tuning a diesel engine

After our diesel turbo issue en route to Flagstaff, Arizona, our friend Ron posed a great question: “What are you doing to avoid a repeat of the turbo fault?” he asked. “Limping with a big rig behind doesn’t sound like fun.”

That didn’t sound like fun to us either. Although Bob had successfully reset the codes the truck had pulled, we wanted to make sure we didn’t have a repeat incident. 

Having sensed some issues with our two truck batteries, we decided to proactively replace them — in a Walmart parking lot in Page, Arizona. After all, they were more than three years old. We parked near a collection of RVs and got to work. About 45 minutes later, we returned the old batteries to Walmart to regain our core charges and stock up on supplies. 

Finding a fix

We knew that wasn’t enough to correct the turbo fault. When we had our truck’s turbo replaced in December 2024, the shop that completed the work had recommended tuning the diesel engine as well. That would have been another couple of thousand dollars on top of the $6,600 we were already forking out, so we opted not to pursue it.

After our turbo issue near Flagstaff, however, we thought the tuner might be worth the investment, especially once we realized we faced an 11,000-foot mountain pass on our route across Southern Colorado.

We had the tuner shipped to a Boondockers Welcome host’s site in Yellow Jacket, Colorado, near the Four Corners, and paid for expedited shipping to ensure we’d receive it in time. 

It arrived a day late but was nowhere to be found after the UPS driver had called us and confirmed he left it at our rig. A stressful hour later, the host’s grandson delivered the package to us. He had picked it up thinking it was for his grandmother, whose name appeared on it in addition to ours.  

Installing the tuner

The next day, Bob installed the tuner. The process required inserting a bypass cable for the On-Board Diagnostics (OBD) sensor under the truck’s dash to allow the tune to take place. 

Bob loaded an app onto his phone and then downloaded the tune settings the company had made specifically for our Dodge Ram 3500 dually through the app. He applied those to the vehicle following the guided instructions in the app. 

After that, Bob attached a switch under the dash and connected it to the OBD port. It enables us to manually transition between five tuner settings: 

• Heavy tow
• Light tow
• Sport
• Street 
• Optimized stock 

With the installation complete, Bob took Gulliver for a test-drive to see if he could detect any performance increase. 

Assessing the new tuner

We knew the real test would come when towing our 18,000-pound fifth wheel, Tagalong. A couple of camping stops later, an 11,000-foot peak and the Continental Divide loomed between us and our next destination. With snow in the forecast, we were eager to get beyond the summit. 

We set out, trying to stay ahead of predicted windy conditions. But our stop at a gas station to dump our wastewater tanks, refill our propane, and add air to a tire with a slow leak turned into an hour. The tire wouldn’t take air. Bob put in as much as he could as the wind picked up. 

Butterflies in our stomachs, we headed toward the pass with the tuner set to heavy tow, hoping and praying we’d make it up and over with no issues. The climb started gradually, with two lanes for ascent. Faster vehicles passed on us on the left as the speed limit dropped, making the wind less of a concern.

We reached the summit safely with plenty of power and successfully began our descent, noticing the truck automatically downshifting, something it hadn’t done before. As we passed small towns with flags flapping in the wind, we counted our blessings. 
 
We’re pleased with the tuner and glad we invested in it. In addition to increasing our truck’s performance, it gives us diagnostic data about the operation of the truck.

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