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Your Diesel Questions Asked and Answered

You’ve Got Questions, We’ve Got Answers

Bruce W. Smith
Oct 7, 2019
EcoDiesel Reflash
QUESTION: I live in Texas and bought a 3.0L EcoDiesel V-6-powered '15 Jeep Grand Cherokee Summit from a friend in California. Since the situation between FCA and the EPA began, I have been receiving mailers telling me to contact my local Dodge/Jeep dealer to have the emissions-software reflash done to the ECM and they will pay me, as the owner, $3,700 for doing it. My concern is: I was informed by a very knowledgeable mechanic that this [stock] reflash is destroying the engine by dumping excessive fuel into it, destroying the EGR cooler, DPF, and burning out the sensors for the aftertreatment system. Basically, the procedure is ruining a proven engine that was easily rated at 400,000 miles with regular maintenance.
via email
ANSWER: There's a lot of unwarranted news circulating out there among EcoDiesel owners, regarding the emissions-software update that is a result of Fiat Chrysler Automobiles (FCA) run-in with the EPA concerning '14-to-'16 EcoDiesel-equipped Ram 1500s and Jeep Grand Cherokees allegedly surpassing the allowable limit of nitrogen oxide (NOx) through their smog system and running afoul of the Clean Air Act. In 2019, FCA sent out notification letters to owners of some 104,000 affected vehicles to have the free repair (reflash) of the ECM that has been approved by both the EPA and the California Air Resources Board. In addition to the reflash that controls the selective catalytic reduction's (SCR) pollution control system, FCA gives the owner an extended warranty that covers all the related pollution-control parts. According to FCA and California court filings, the ECM software update does not affect the durability, fuel economy, or driveability of the vehicles. What you'll see is a higher rate of diesel exhaust fluid (DEF) consumption, because the urea in DEF is what combats oxides of nitrogen (NOx). We're told that for those who drive at sustained high speeds or sustained low speeds, such as in slow city traffic with frequent stops, there might be a decrease in mpg, as those conditions are when SCR is the most aggressive. As for the reflash "destroying the engine" and "burning up" or "destroying" an EcoDiesel's pollution control system components, we think not. According to the agreement FCA reached with the EPA, they must test the affected vehicles for five more years to make sure all is well when it comes to emissions standards. So it's in FCA's best interest to make sure there are no other related glitches, such as destroying the very components that keep the emissions in check. Our advice: Contact your local Jeep dealer per the letter and take advantage of the free repair, the extended warranty—and the nice check you get for your time sitting at the dealership.
7.3L Tow Help
QUESTION: My wife and I will be buying a fifth-wheel trailer that has a GVWR of 12,000 pounds. We have an '03 Ford F-250 with the 7.3L Power Stroke engine that serves as our tow vehicle. It's been great pulling a 7,500-pound travel trailer. But I know the bigger unit will be more of a challenge. What suspension changes can we make to our old truck to make it handle the bigger trailer better?
Darren K.
via email
Photo 2/5   |   Installing thicker, stronger aftermarket antisway bars front and rear, helper springs, and an ECM calibration for towing greatly improves the stance and overall performance and handling of older diesels that tow trailers. The heavier the trailer, the more it's necessary to enhance the suspension—and the use of weight-distributing hitch.
ANSWER: According to Ford's "2002 RV and Trailer Towing Guide," the maximum tow rating for an '03 F-250 is 12,500 pounds using a weight-distributing hitch. To maximize handling when a pickup is pushing the upper limits of the factory-prescribed tow rating, we suggest replacing the stock rear sway bar with a stouter version, such as Hellwig Products' Big Wig Series antisway bars. It will also be beneficial to have rear helper air springs, which are available from several different sources. Properly adjusted spring bars on a weight-distributing hitch will keep the truck's stance somewhat level, but air helper springs and the bigger rear sway bar will provide better ride and overall handling when used in conjunction with the hitch. Replace the shocks at all four corners, too. High-quality high-pressure gas shocks, such as Bilstein or Fox Factory 2.0-inch Performance IFPs, do wonders for ride when towing heavy. Also, step up to Banks' PowerPack Bundle. This kit adds about 105 hp and 224 lb-ft of torque to the 7.3L, which is an enormous help when tackling the highways and grades, and it maximizes turbocharger efficiency while lowering EGT (exhaust gas temperature). The CARB-compliant kit comes with a new intercooler and exhaust, plus a Banks Quick-Turbo upgrade kit and programmer. Banks also claims the system improves towing fuel economy by about 14 percent.
Ford 6.7L Turbo Retrofit
QUESTION: The 6.7L Power Stroke engine in my '13 Ford F-350 quit making power when towing an equipment trailer over a mountain pass. I had the truck towed to the nearest Ford dealer, where I was informed the turbocharger failed. Unfortunately, it's just out of warranty. Is there a better turbo I can replace it with? One that will keep the engine smog legal but is better than the one that failed?
Mark W.
via email
ANSWER: Ford's dual-intake, wastegated, SST turbocharger used in '11-to-'14 models was a state-of-the-art variable-geometry turbo at the time. The dual-wheel compressor made the turbo very quick spooling and produced a lot of low-end power. But it was not known for its reliability and didn't have the best grunt at the top end. That's why Ford went to a completely different VGT turbo on the '15-and-up 6.7L Power Stroke that uses a single-plane compressor wheel, journal-type bearings, and no wastegate. The design is similar to the chargers used on Ford's 6.0L and 6.4L diesels, and older 6.6L Duramax powerplants. But the newer-style turbo has an 18mm larger compressor wheel (61 mm) and a 3mm larger diameter turbine wheel on a considerably thicker shaft than the piece used in the earlier 6.7L. The result is a much more reliable and efficient turbo that delivers enough air to make upward of 540 to 580 hp. The good news is there's a bolt-on Ford Racing kit to drop a '15-and-newer turbo onto the first-generation 6.7L engines. (Check out KC Turbos for more details). The complete kit, which costs around $2,900, comes with every part needed to make the performance swap, from gaskets, studs, and bolts to up-pipes, downpipes, coolant lines, and turbo. It even includes all the components to keep the engine emissions compliant. The downside is the newer turbo lacks the same fast low-end oomph of the old model. The upside is the new turbo will out-pull the older one once the engine reaches about 2,000 rpm, because it makes about 60 hp and 100 lb-ft more torque across the upper powerband. Retrofit your truck with the '15 stock turbo and matching high-pressure fuel pump, along with tuning, and the power, fuel economy, and reliability benefits are even greater—and it's still all stock Ford parts.
Fuel Cooler Issue
QUESTION: I just realized the little reservoir for the fuel-cooling system on my '10 Ford F-250 is nearly empty and it has this thick, red residue in the bottom. Should I be concerned? I just bought the truck, and I think I'm the third owner. This is my first Super Duty, so I am trying to learn as I go.
Tim Friedman
via email
Photo 3/5   |   Keeping the Ford 6.4L Power Stroke engine's fuel cooler and the entire secondary cooling system in good operating order is essential to the health of the high-pressure fuel pump, turbocharger-actuator, and overall engine performance. Overly warm fuel doesn't lubricate and reduces engine power.
ANSWER: Yes. Whenever the fuel-coolant reservoir is empty, there's cause for concern. We highly recommend checking to make sure the pump is working correctly and ensuring the fuel-cooling system is flushed and refilled with a good antifreeze/coolant approved by Ford. The primary job of the fuel cooler on the 6.4L Power Stroke engine is to protect the high-pressure fuel pump and turbocharger actuator from getting too hot, and to cool the excess fuel returning to the tank after it's gone through the pump and injectors. The fuel-cooling system is standalone, completely separate from the engine's primary cooling circuit. It's powered by its own electric pump located on the bottom of the fan shroud on the driver side, and its "radiator" is mounted to the right (driver side) of the intercooler. The fuel-cooler recirculation pump doesn't run all the time. On/Off operation is triggered by the ECM. Diesel fuel gets hot when it is pressurized between 5,500 psi to about 24,000 psi. The hotter diesel fuel gets, the lower its lubricity properties, and, as the heat of fuel rises, the lower the density of the fuel injected into the cylinders. In short, hot diesel fuel will not properly lubricate the high-pressure pump or the turbo actuator—and hot fuel cuts down power. To combat this rise in fuel temperature, coolant circulates from the fuel-cooler pump to the fuel-to-coolant heat exchanger mounted on the turbo's connection tube on to the reservoir, and then to the turbo actuator. From there, the coolant flows to the fuel cooler's air-to-coolant heat exchanger mounted by the radiator, and then back to the pump. Cooling the fuel is vital to the life of the injection pump and overall engine performance, and the hotter the ambient operating temperatures, the more fuel cooling plays a role.
Here's how Ford's workshop manual explains the heat issue: "The fuel-cooling system is designed to keep the high-pressure pump inlet and fuel tank return below 158 degrees Fahrenheit. The coolant pump is turned on by the ECM when it receives a signal from the fuel-temperature sensor, indicating the fuel temperature in the fuel-filter module has reached 35 C (95 F). The ECM turns off the coolant pump when it receives a signal from the fuel-temperature sensor indicating the fuel temperature is below 20 C (68 F). The coolant pump will be on under most operating conditions. The fuel and turbocharger-cooling system is also designed to remove some of the heat being transferred to the turbocharger actuator during engine operation and after engine shutdown. The system assists in limiting the temperature exposure to the turbocharger-actuator electronics. The electric coolant pump can run up to 10 minutes after the vehicle has been shut off. This is to remove some of the heat in the turbocharger actuator following engine shutdown. "
Here's an excerpt explaining why heat is an issue from a study on advanced diesel engines by Michael Davies, John Burgers, and Nick Kaiman of the NAPA Echlin Corporation, a major manufacturer of diesel-injection products for both OEM and aftermarket: "With a starting point of 100 percent power with the reference fuel temperature of 45 C (113 F), without cooling, without heating, HSDI engine performance values decrease or increase, as the fuel temperature rises or falls respectively. Of particular interest is the initial fuel heating of 10 C from 45 C to 55 C, Which leads to a significant performance reduction of 7.5 percent. A drop in the diesel fuel inlet temperature from 45 C to 25 C results in a performance increase of 5 percent, and raising the fuel temperature from 45 C to 80 C leads to a performance reduction of 14 percent. Performance continuously falls by 19 percent with rising fuel temperature (from 25 C to 80 C), but the fuel consumption remains constant throughout. The injected fuel volume falls with rising temperature, which is the direct result of a decreasing diesel fuel density with rising temperature. The lowest fuel consumption occurs at a fuel temperature of 45 C. As mentioned above, this is the reference temperature used in the diesel engine industry for establishing combustion processes. The injected energy quantity continually falls with rising fuel temperature, from 25 C to 80 C. The specific fuel consumption also stays relatively constant, the best point being at 25 C fuel temperature and increasing insignificantly up to 45 C HSDI engine fuel temperature tests demonstrate clearly that changing the fuel inlet temperature from the standard temperature of 45 C has a significant effect on performance levels. From 45 C (113 F) to 80 C (176 F), the power drops by 14 percent, and when the fuel is cooled from 45 C down to 25 C (77 F) , performance increases by up to 5 percent. "
Our friend Kenneth Tripp at Tripp Trucks in Rock Hill, South Carolina, offers this advice related to flushing the fuel cooling system: "Disconnect the hose going from the turbo actuator to the coolant expansion tank to drain both prior to pulling the hoses off the fuel-cooling-system radiator. This keeps any oil or contaminants that might have accidentally gotten into the system from draining right back to the lowest point (bottom of the radiator). This also makes the flushing process go faster. Flush the system with water and soap (Dawn or Purple Power work great). To bleed the system without a commercial radiator re-filler, remove the front bumper, take the single bolt out of the top securing the fuel-cooling-system radiator, slide the radiator upward, and then lay it horizontal. Next, remove the plug from the top of the turbo actuator and fill the system through the expansion tank until coolant comes out of the hole for the actuator plug. Reinstall the plug and put it all back together." Kenneth says it's prudent for anyone buying a used 6.4L-powered Super Duty to have a reputable diesel shop or Ford dealer use a Ford IDS to do a complete system scan of every module on the truck, because "the 6.4L is very good at hiding issues especially with how it can adjust Short Fuel Trims to make it run as good as possible to where the average guy might think it runs perfect even though it could have an injector adding or pulling fuel outside the normal operating range. "
About Injectors
QUESTION: Is it safe to buy "rebuilt" injectors instead of new ones? Does rebuilt mean the same thing as refurbished or remanufactured? It's confusing to me, but the stock injectors in my '07 Dodge Ram 2500's 5.9L Cummins engine are in need of replacement, and I'm seeing a wide range in prices.
Steve Smith
via email
Photo 4/5   |   Beware when buying replacement injectors. There's a big difference in the quality, longevity, and performance between new, rebuilt, refurbished, and remanufactured, depending on who performed the work and the parts that were used.
ANSWER: The quality of a set of injectors is based on whose hands were on them and what parts were used when they were made. When purchasing injectors, read the fine print that covers how they are built and tested. Not all suppliers use the same means and methods. As for terminology, "new" means new. But "rebuilt," "refurbished," and "remanufactured" don't always necessarily mean exactly the same across all suppliers. We asked several sources about the differences in injectors and terminology, and here's what we learned: InjectorsDirect.com, which has state-of-the-art injector testing, cleaning, and calibration equipment in a new facility opened in 2018, says, "Refurbished injectors are removed from running engines, cleaned (internally and externally), then individually evaluated on a test stand to ensure they meet OEM specifications. Remanufactured injectors have been disassembled and inspected for wear, then rebuilt using new components and individually evaluated on a test stand to ensure they meet OEM specifications. OEM injectors have been disassembled and inspected for wear, then rebuilt using new and often updated components (nozzles, solenoids, plungers, valves, seals, and such) then individually evaluated on a test stand to ensure they meet OEM specifications. This process is carried out by the manufacturer (Bosch for GM, Mopar for Dodge Ram, and Seimens/Motorcraft for Ford). These are the same injectors you would get from the parts counter at your local factory-authorized dealership. New injectors are just that: brand new. Every component of the injector is new (including the body). These are built by Bosch for Duramax and Cummins applications. "
Mark Gotchall at Oregon Fuel Injection, which has been providing full fuel-injection services and diesel repairs since 1974, says, "As with every product, the quality of a rebuilt injector depends on the parts used and proper procedures employed. We use and sell Bosch factory-rebuilt injectors, which have a very low failure rate. Non-genuine parts, reuse of normal wear parts, or honing versus replacement can cause an injector to not operate properly. We've tested several sets of non-genuine injectors using the Bosch EPS205 test bench. The failure rate per set ranged from 100 percent to 0 percent, with most sets having about a 33 percent failure rate. The most common failure is improper fuel delivery at pilot injection, which helps make the engine quieter at idle. Too much or too little fuel will cause the engine to have a slight knock at idle. We have also found nozzles that leak under pressure, which will cause white smoke at idle. In our opinion, Bosch or Bosch-authorized rebuilt injectors are good products and should last as long as new, if properly rebuilt." With the investment in time it takes to replace injectors in diesels, it seems investing in ones that are the most likely to provide the best performance and longest life would be the best choice. On the other hand, if you're just doing a barnyard quick fix to get an older diesel ready for sale or trying to cut every budgetary corner in injection repair, then going the cheapest route is understandable. Generally speaking, one gets what they pay for when it comes to injectors. With your truck's 5.9L Cummins, don't forget to replace the fuel-connector tubes once the injectors are installed. Reusing the old ones can lead to leaks.
No Axle-Ratio Option
QUESTION: In checking out the new '20 GM 2500HD and 3500HD rigs as I get ready to replace my aging '08 pickup, I can't find any options for axle ratios. It looks like they only have 3.42 gears. What's up with that? My current pickup has 3.73 ring and pinion, and that's ideal gearing for how I use it.
Brandon Taylor
via email
Photo 5/5   |   The '20 Chevrolet and GMC HD 2500/3500 heavy-duty diesel pickups have only one axle ratio available: 3.42:1. The all-new, GM-built Allison 10L1000 10-speed automatic transmission's extra-low gears and wide range of gear splits eliminates the need for buyers to fret over which axle ratio to order when buying a new truck.
ANSWER: Welcome to the new era of heavy-duty diesel pickups! You are correct. The '20 GM rigs are only offered with 3.42 rearend gear ratios. The axle options are relegated to open, limited-slip, or locking rear differentials, depending on the platform. The reason for the single-ratio axles is because GM's all-new Allison 10L1000 10-speed automatic transmission has a wide enough gear range that it covers the equivalent of older pickups running 4.10 gears. In fact, the new 10-speed provides the equivalent of a "granny-low" First gear. The Allison 1000 five- and six-speeds have a First gear ratio of 3.094:1 and 1.809:1 Second gear. In contrast, the 10-speed's First gear is 4.54:1, Second is 2.86:1, Third is 2.06:1, and Fourth is 1.72:1. Those lower first three gears essentially take the place of axle ratios between 3.55 and 4.10 when combined with the 6.6L Duramax L5P engine's 445 hp and 910 lb-ft of torque. There's also more power being delivered in those lower gears in the '20 model thanks to a new torque converter that now locks up in First gear (the old model didn't lock up until it was in Third—and sometimes Fourth gears). The 10-speed is one of the big contributors to the new GM heavy-duty having up to 52 percent greater towing capacity than the previous models, with a tow rating up to 35,500 pounds. By the way, the 10L1000 transmission starts in Second gear unless it's in "Tow/Haul" mode, then it launches in First, delivering the full power of the 6.6L, according to Tim Herrick, GM's executive chief engineer of the Heavy Duty program. So, don't sweat not having a choice in axle ratios when you buy your new GMC Sierra or Chevrolet Silverado. The 10-speed Allison has you covered.
Hard Start 6.0
QUESTION: Is it possible to economically fix the problems of an '05 Ford F-350 with a 6.0L engine? I've already spent more than $3,000 on this truck (only 47,000 miles) since I bought it. The current problem is the engine starts fine cold but may or may not start once it's warmed up. The mechanic who is helping me seems stumped.
B. Wesson
via email
ANSWER: The 6.0L and 6.4L Power Stroke engines have a litany of mechanical issues that are well documented, and the fixes have been covered in depth over the years in the pages of this magazine, by diesel-repair shops, and on aftermarket suppliers' websites, not to mention in a host of Power Stroke-specific Internet forums. A recurring claim is "fixing" these diesels so they are reliable and trouble-free can cost upward of $10,000. Our first "guess" is there's a high-pressure oil leak around the O-rings, or the injection-pressure regulator (IPR) is not functioning properly. But the only way to verify such things is by using a scan tool and watching the IPR duty cycle and ICP (injection-control pressure) voltage. Without a scan tool, you're blind when it comes to diagnosing diesel issues of this nature. If there's a leak around any of the O-rings, both would probably be in the normal range when starting cold and out of specification when the oil is warmed up to operating temperature and when starting while warm. That aside, Oregon Fuel Injection has a very helpful section on its website that details diesel troubleshooting steps for Power Stroke, Duramax, and Cummins engines. It's a great free resource for anyone seeking insights and instructions related to diesel diagnostics and repair. The last half of the Power Stroke section (oregonfuelinjection.com/services-repair/diesel-diagnostics-repair/ford-diesel-diagnostics/) details the steps to diagnose "No Start/Hard Start" issues related to the 6.0L. At the very beginning of the 6.0L diagnostics section, it states these important notes:
  • You must be able to use the Ford factory IDS scan tool for 6.0L diagnostics due to the number of PCM updates. There are so many driveability issues that are solved with a new PCM calibration that attempting repairs without the IDS scan tool is an exercise in futility. Be aware that after the PCM is reflashed, it may take up to 1,000 miles for the PCM to relearn how you drive. During this relearn procedure, it is very likely your mileage will drop. Ford does not have a quick learn procedure like GM or Chrysler; they are "slow learners. "
  • There have been many changes to the 6.0L and getting the correct parts for it depends on the engine serial-number range. The serial number is located on the FICM, which is on the top of the left valve cover. If the FICM has been replaced, you may need to get the serial number off the engine block. The serial number is stamped into the block at the left rear of the engine, just under the head.
  • Diagnosing starting problems and driveability problems requires you start at the basics. The HEUI system uses engine oil to actuate the injectors; if you are low on oil, you will have problems.
  • Check the oil and change the oil if it is due. If the oil is worn out from excessive change interval, you will have problems. Oil change intervals are critical.
  • Fuel filter plugging will cause issues. Has it been more than 10,000 miles since you changed the fuel filters? Change the filters before proceeding with further diagnostics.
  • Air in the fuel will cause injector failures. Inspect the fuel for signs of contamination and/or air intrusion when you change the filters.
  • Avoid long idle times; long idle times will cause the EGR and turbo to carbon up excessively.