Exclusive Content
Original Shows, Motorsports and Live Events
Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit www.motortrend.com for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM

Diesel Tech Questions

Top Tech

Bruce W. Smith
Jan 30, 2018
Photographers: Bruce W. Smith

Alaska Bound

QUESTION: The 6.6L Duramax LLY engine in my ’04 GM pickup has 105,000 miles on it and a Check Engine light is showing. After scanning the ECM, I found out the problem is associated with diagnostic trouble code P0045 (boost-related issue concerning the turbocharger’s vanes). I delete it, and it comes back after a few hundred miles. My repair shop says the problem is more an inconvenience and not worth the expense of installing a new turbocharger. I am planning a boating trip up to Alaska and don’t want any major problems. Would this cause a breakdown or something close? Advice on how to handle this is appreciated.
W. S. Hancock
via telephone
Photo 2/5   |   Diagnostic-trouble code P0045 and/or P003A can be caused by numerous issues related to turbocharger vanes, including a bad wire to the control solenoid or a sticking solenoid or turbo vanes. It could also be triggered because boost pressure is bleeding from a leak in intercooler boots or tubes.
ANSWER: Whenever a diagnostic trouble code is triggered, trying to determine its cause and making the appropriate repair is always the best way to proceed. Ignoring DTCs for too long is not recommended. The code in your truck’s ECM, DTC P0045, could pertain to the turbo’s vane-control solenoid, which receives a command from the ECM to change the angle of the vanes according to the load placed on the engine. The control solenoid has two circuits—High and Low. The ECM communicates with the solenoid to control the position of the turbo vanes. Changing the vane angles increases and decreases boost. If the ECM sends a signal to the solenoid and the solenoid doesn’t respond correctly within 1 second, the ECM senses there is a boost issue and triggers DTC P0045 and/or P003A. The causes for the code are numerous: a bad wire to the control solenoid, a bad or sticking control solenoid, or sticking turbocharger vanes. It could also be activated because boost pressure is bleeding from a leak in the intercooler boots or tubes. Usually, the cause is directly related to carbon/soot buildup either on the end of the boost-control solenoid or around the vanes inside the turbo. To get to the root of the problem, the first task is to use a scan tool and run a diagnostic on the solenoid by turning it on and off. According to GM’s 6.6L Duramax service manual, the vane-position sensor’s parameters should be 95 to 97 percent when it’s on, decreasing to almost 0 percent when it’s off. A sticking solenoid can be removed, cleaned, and re-installed, while a defective part is easily replaced. If the solenoid checks out, then pressurize the boost tubes to the intercooler to see if there are any leaks from bad boots or loose clamps. If that part of the system is good, then the problem is likely associated with sticking turbo vanes, and that usually requires replacing the ’charger, because it’s very difficult to thoroughly clean the vanes. Any residue left behind will act like a magnet, quickly attracting soot, so the same problem would return months later. A good diesel shop can perform all the tests to diagnose and remedy the problem.

Ticking Cummins

QUESTION: This might be a stupid question, but how often should I have the valves adjusted in my ’04 Dodge Ram’s 24-valve 5.9L Cummins engine? She’s starting to tick a bit loudly at 196,000 miles. I’m the second owner, and I don’t know when they were adjusted prior to me buying it. Should I go by the Dodge Ram owner’s manual on mileage, or is there some other criteria that helps determine the best service interval? It’s a great-running truck, and I want to do everything I can to keep it that way for a long time.
Russ Petersen
via telephone
Photo 3/5   |   Valves that are out of adjustment on a diesel engine—even if it’s only by a small amount—have a direct affect on fuel economy and power. According to the ’04 Dodge Ram owner’s manual (p. 394), the maintenance-service schedule for 5.9L Cummins engine calls for valve-lash adjustment to be performed at 135,000 miles under Schedule “B,” which applies to trucks used for frequent short trips or towing, or driven in city-type conditions.
ANSWER: Increasingly louder ticks coming from under the valve cover are the engine’s way of saying: “I need attention.” In a diesel engine, valves that are out of adjustment— even if it’s only by a small amount—have a direct effect on fuel economy and power. According to the ’04 Dodge Ram owner’s manual (p. 394), the maintenance-service schedule calls for valve lash adjustment to be performed at 135,000 miles under Schedule “B,” which is when the truck is used for frequent short trips, towing, or driven in city-type conditions. Schedule “A” (non-towing use and long trips) recommends valve lash be adjusted at 150,000 miles. Both schedules also recommend oil changes every 7,500 miles or when “prompted by the Engine Oil Indicator System.” However, when we talked with several respected diesel-repair shops, they told us the factory-recommended service interval is performed on a much sooner basis with their customers. Mobile Diesel Service, which deals with a lot of contractors and loggers, likes to adjust the valves at 100,000 miles, then every 50,000 from then forward. Source Automotive, a Dodge/Cummins-only service center and diesel performance shop, recommends to its customers to have the valves adjusted every 50,000 miles, or at one-third of the mileage Dodge recommends. “Over the years, we’ve caught several 24-valve issues prior to catastrophic failure by recommending and performing valve adjustments at an earlier service interval than Dodge recommends,” says manager Bill Allen. “It also keeps the engine running as quietly and efficiently as possible. Preventive maintenance is key in our opinion.” The intervals at which maintenance service is performed is totally up to the owner. We like to change the oil in our own diesels every 5,000 miles—and have the valves adjusted at every tenth oil change, which is about once every three years.

On the Rollers

QUESTION: I am getting ready to put my 6.6L Duramax-powered ’07 GM pickup on a local performance shop’s Mustang chassis dyno. But before I do, is there a way to lock the Allison 1000 automatic transmission in Fourth gear so it doesn’t downshift when it’s being tested? I’ve been playing with it on the road, using the Overdrive button and Tow/Haul mode, but it still keeps downshifting when I nail the throttle. It has a Stage 1 Garrett turbocharger and Edge Attitude with Juice programmer.
Chip Rodgers
via e-mail
ANSWER: Our suggestion when it comes to making pulls on any dyno is to let the dyno operator do all the “driving.” They know their dyno and usually have a lot of experience getting different trucks’ automatic transmissions to function in the best way possible for repeatable numbers. The key is to turn Overdrive “Off” and roll just hard enough into the throttle to keep the transmission from downshifting. That takes practice. (Tow/Haul mode just changes the TCM algorithms to a more aggressive level where shift points happen 300 to 400 rpm higher, and the torque converter locks in Second gear at around 25 mph, which helps reduce EGT.) As you noted, your rig’s Allison has the Overdrive Disable button on the end of the shift stalk; pressing and holding it in until “O/D Off” appears on the dash keeps the transmission from shifting into Fifth gear. This is the perfect scenario for making a dyno run: The transmission is locked in whatever gear gives a 1:1 engine speed to transmission speed ratio during testing and remains in that gear with no downshift through the entire sampling window (typically rpm-based). John Lambert, the head of the tuning department at Hypertech, says he sets up the company’s in-house dyno so it replicates the wind drag and curb weight of a test truck as if it were running unloaded on the road. On GM rigs, he turns the Allison transmission’s Overdrive Off, and then accelerates until the gearbox shifts into Fourth gear (around 50 mph), backs off the throttle to get rpm down around 1,500, then rolls slowly back into it until it’s matted, and the wheel speed is up to around the equivalent of 100 mph. The object is to keep the transmission in Fourth from about 1,500 rpm to 3,100 rpm, or whatever the upper-rpm level is for that engine, while getting maximum boost from the turbo as early as possible. “This process produces accurate, repeatable numbers under realistic loads for the street,” John says.

Mountain Towing

QUESTION: My wife and I are retired. We sold our home on the East Coast, and we are planning to take a year-long trip to see as much of the country as we can. We tow a 30-foot Coachman fifth-wheeler behind a ’16 Ford F-250 with the 6.7L Power Stroke engine. The trailer weighs a little more than 11,000 pounds. It’s my first diesel. I’m concerned about overheating the turbocharger, so I added Edge Products’ Insight monitor to see the EGT. When we get into areas where we are towing through the mountains, is it better to leave the transmission in Drive and lug the engine, or manually downshift to bring up the rpm and hopefully minimize EGT? What temperature should be a concern?
Karl Wilson
via email
Photo 4/5   |   Ford’s newest Super Duty has new tow ratings that no longer require the use of weight-distributing hitches to tow a trailer at the maximum capacity. However, using a weight-distributing hitch can improve the driving experience on any truck that’s approaching its maximum tow rating.
ANSWER: Allowing a turbodiesel to lug under a load drives EGT up, because an excessive amount of fuel is being fed into the engine when you’re hard on the throttle, trying to maintain speed and momentum on a grade. Use the transmission’s Tow/Haul mode, which raises shift points several hundred rpm and locks the torque converter earlier in a lower gear. If EGT still climbs, shift into a lower gear that will keep rpm in the upper third of the engine’s operating range. Higher rpm speeds up the turbocharger and gets hot exhaust gases out of the cylinders faster than lower rpm. Common towing practice is to keep EGT between 1,100 and 1,200 degrees with very short spikes to 1,400. On stock trucks, the ECM will usually back off the fuel when the processor senses EGT is in that red zone. Hold the EGT above 1,400 for any extended period of time—for example, climbing a steep, continuous half-mile grade—and bad things are probably happening under the hood. Speaking of EGT, when you pull over after towing, let the engine idle for a minute or two to let the temperature drop down to less than 400 degrees before shutting down the engine. This helps limit coking (from burned oil) and helps the turbo cool down. Turning the engine off while the EGT is high leads to “heat soaking” everything under the hood, which ultimately promotes premature failure of parts.

D-Max Camaro

QUESTION: My 16-year-old son and I are about to take on a special diesel project together: building a diesel-powered Chevrolet Camaro. The donor car is an ’02 model, and the engine is an ’06 6.6L Duramax LBZ with an Allison 1000 automatic transmission. We are at a bit of a loss regarding what to do about the wiring, as the harness and ECM that came with the engine and transmission look a bit suspect. We have the mechanical and plumbing aspects of shoehorning the engine and transmission into the Camaro covered. Is there anyone out there who might be able to get us on the right wiring path before we dive headlong into our sleeper?
Bryan Rigby
via email
Photo 5/5   |   Duramax diesel-engine swaps are becoming increasingly popular now that there are many viable sources throughout the U.S. for the wiring harnesses that simplify the conversion process.
ANSWER: It sounds like a fun project that will definitely turn more than a few heads. We know of at least two Duramax/Allison wiring-solution sources, both in Florida: DMAX Swap [(816) 866-3629] and Standalone Harnesses [(321) 604-1963]. Both can provide the wiring harnesses to make integrating the engine and transmission as easy as possible or rework your existing harnesses to do the job. DMAX can also handle the ECM/TCM calibrating at the same time and maybe provide some specific information about the diesel swap you’re doing, as the crew has done at least one similar installation in a Camaro. Ken Wolkens at Standalone is a retired GM engineer who knows Duramax/Allison wiring logic inside and out, and he also custom builds harnesses to fit just about any Duramax swap. Between the two suppliers, you and your son should be good to go.

No More WD

QUESTION: I have a 35-foot bumper-pull travel trailer that weighs 10,000 pounds. I never needed a weight-distribution hitch for my old trailer (7,000 pounds) when towing it with my ’17 Ford F-250. How heavy of a trailer can my truck tow without a distribution hitch? Ford claims there is no longer a need for that type of hitch on the ’17 Super Duty, but mine bounces pretty severely at times.
Sherman Wakefield
via the internet
ANSWER: Ford, indeed, changed its towing specifications and requirements on the ’17-and-up Super Duty. Using a weight-distributing hitch is no longer a requirement when towing up to the maximum rating. Now, the company’s “2018 RV & Trailer Towing Guide” (fleet.ford.com/towing-guides/) lists conventional towing (weight-carrying and weight-distributing) ratings together. That means Ford met the minimum SAE J2807 testing requirements pickup manufacturers are now using to set maximum trailer-towing capacities. Although a manufacturer doesn’t “require” a weight-distributing hitch, using one is still recommend, as it makes a towing experience better by keeping unwanted sway and “bouncing” minimized when approaching those maximum limits (which vary considerably between models, engines, and axle ratios). For example, an ’18 Ford F-250 crew-cab longbed four-wheel drive with the 6.7L diesel is limited to 12,500 pounds on the ball, while a shortbed two-wheel-drive model is rated at 16,800 pounds. When trailer weights get within 2,000 pounds of their maximum, steering and overall vehicle handling tend to get noticeably sloppier. Another point to consider is the weight listed on trailer manufacturers’ tags is “dry,” not loaded with water, food, gear, propane, and other provisions. It’s always prudent to actually weigh a trailer to see exactly how much you are towing, be it a pull-behind or gooseneck/fifth-wheel. Tongue and pin weights have a big affect on handling, so a trailer that weighs more than you expected may be the reason it makes the towing vehicle feel odd. If you do feel a little uneasy behind the wheel when towing a long, heavy trailer, err on the side of caution by employing a weight-distributing hitch and/or helper air springs to bring stability. Such an investment is cheap insurance for both vehicle stability and peace of mind.

Grid-Heater Gremlins

QUESTION: Four years ago, I purchased an ’07 Dodge Ram 3500 with only 40,000 miles. Its 5.9L Cummins engine is completely stock, with the exception of a K&N Engineering air filter. For the entire time I’ve owned it, the grid-heater light/Wait to Start has come on and gone off intermittently when pulling my 12,000-pound travel trailer into the wind or uphill. I had several mechanics check the ECM for codes whenever the light has come on, but they couldn’t find anything wrong. About four months ago, the grid-heater light came on and the truck went into “limp mode” and had no power. My mechanic found diagnostic-trouble code P1222 and replaced the fly-by-wire throttle. That seemed to have fixed the problem. Then, 6,000 miles later, the grid-heater light started coming on again. I took the truck back to my mechanic who then performed a diagnostic check with the engine running. All pressures were good, the injectors were good, and there were no high-pressure internal leaks. The odd thing is, you can simply erase the code and the grid-heater light goes out and the truck runs fine for a while. Then, the light comes back on. The truck has 87,000 miles on it, and I use it eight months out of the year as a daily driver. The other four months it spends towing our RV trailer. I love this truck and don’t want to get rid of it any time soon. I also don't want to spend a lot of money chasing gremlins.
T. Barney
via email
ANSWER: Diagnosing this is complicated because the “Wait to Start” lamp is also the indicator for the grid heater. So, what appears to be one issue can actually be another. For example, the grid-heater relay could be melted, there’s a loose connection to it, or the ECM could be telling it to stay on. Any of those will turn the WTS light on. But it could also be a problem related to the injection system. “We’ve heard Ram owners who bring their trucks in here say, ‘There is no code in it, but the Wait To Start comes on and the seatbelt warning chimes, then the truck loses power,’” says Oregon Fuel Injection’s Mark Gotchall. Several other shops we contacted concur. That’s why we think the issue with your truck’s symptoms points to a leak in the fuel-injection system, specifically excessive injector return, because P1222 is the DTC that triggers. It is a newer trouble code without definitive diagnostic information. However, Ram clearly states: "Here is how and why the P1222/1223 code sets. P1222 is related to fuel pressure, and it’s calculated off the FCA-commanded position and the rail pressure. If the percentage/pressure is out of the manufacturer’s parameters, then the wait-to-start light comes on and the seatbelt warning chimes 10 times. It only happens on ’05-to-’07 5.9L.” On top of that, many aftermarket scan tools don’t even have the P1222/P1223 codes in them unless they’ve been updated with the most current database. So, the DTC can be there, it’s just not showing up on the scan tool being used. The following is an excerpt from the diagnostics information provided to us by Oregon Fuel Injection: DIAGNOSTIC PROCEDURE P1222 - LEAK DETECTION DURING MOTORING. When the engine is idling, the only required fuel delivery to the rail is due to natural leakage in the system. The natural leakage depends directly on the rail pressure. A definitive amount of fuel is required to overcome the natural leakage for different fuel pressures. The Engine Control Module sets a leakage-detected code and initiates a counter when the fuel flow exceeds an expected value. When the counter reaches a predetermined value, a fault [P1222] is set and engine de-rate is enabled. When the leak is not detected, the counter starts, and once it reaches zero, the engine is set back to normal running conditions. When Monitored: Engine is motoring and at operating temperature with no fuel-system or engine-speed–related DTCs. Set Condition: Counter reaches a calibrated value. Possible Causes: Excessive Injector Return. Potential fixes [repair/replace] are as follows:
• Fuel Injector(s)
• Diesel Fuel Injection Pump
• Fuel Connecting Tube Nuts
• Fuel Rail Pressure Limiting Valve
• Fuel Injector(s) and Fuel Rail Pressure Limiting Valve
• Cascade Overflow Valve
• Aftermarket Programmer

Old Iron Diesel Swap

QUESTION: I have a ’71 Ford F-100 with a 302 V-8 engine that I would like to swap with a diesel. I was thinking about going with something smaller, like the 3.9L Cummins. Do you have any recommendations on that engine, or other engines similar in size to the 3.9L, that will work well with my old Ford? Or do you recommend going with a 5.9L? Is a manual transmission better than an automatic for such a swap?
James Shenahan
via email
ANSWER: The popularity of diesel swaps into older classics such as your F-100 is on the rise. There are multiple ways you can go, depending on the amount of time and money you want to invest. The simplest and least expensive swap involves finding a donor ’01-to-’04 Dodge Ram 2500 that has the NV5600 six-speed manual transmission and high-output 5.9L Cummins engine. The 24-valve 6BT is a heavy beast, weighing 1,100 pounds, so there is definitely a need for front-suspension upgrades on the truck. The upside is the high-output engines make 325 hp and 600 lb-ft of torque without any modifications, and a few modest performance upgrades can easily add another 100 hp and 200 lb-ft. Having a complete donor truck obviously eases the wiring and plumbing issues. Another possible route is sliding in the new Cummins 2.8L crate engine, which comes complete with a plug-and-run wiring harness. The state-of-the-art I-4 engine is rated at 161 hp and 267 lb-ft of torque, yet it only weighs a little more than 500 pounds, giving it a higher power-to-weight ratio than the 5.9L and considerably better performance on all fronts than the old 105hp, 780-pound 3.9L 4BT. It would also be almost identical in weight to your truck’s current 302, so you wouldn’t have to be concerned about making suspension modifications. There are several companies that specialize in Cummins conversions who already have, or can build, the adapter for whichever transmission you want to mate to the engine of your choice, and several companies make standalone automatic-transmission wiring harnesses. A good place to start any Cummins swap related to old iron would be Auto World Conversions [(406)727-8915] in Great Falls, Montana. Also consider putting a 6.6L Duramax engine and Allison 1000 six-speed automatic transmission in your F-100. A Duramax weighs about 835 pounds and makes 360 hp and 650 lb-ft of torque, and the Allison is a fine automatic. There are several companies across the country that specialize in wiring harnesses for that application, including BT DieselWorks [(307)200-9255] in Boston. Whichever diesel conversion you choose, an intercooler, custom exhaust, and a quality, high-flow aluminum radiator will also be part of the swap.

Blown Fuse

QUESTION: My 70-year-old father has a ’97 Ford 7.3L diesel pickup. He has had an issue with the #30 fuse intermittently blowing when he turns on the key. He replaced the fuse several times, and when it blows, the engine will not start. It doesn’t seem to matter if the engine is hot or cold. He’s at a loss for where to look for the cause. Any suggested checks?
Melvin Jones
via email
ANSWER: Fuse issues can be quite frustrating. But the good news is that fuse failing is a common issue on ’99-to-’01 Ford Super Dutys with 7.3L Power Stroke engines. The 30-amp #30 fuse feeds the heater element inside the fuel bowl, as well as the relays feeding the ECM. Those heater elements burn out, blowing the fuse and creating the no-start condition. The good news is the fuel-bowl heater really isn’t necessary unless you are operating your truck in subzero temperatures. Unplugging the wire to the heater or replacing the bad heater element usually solves the blown-fuse problem. Another fuse that seems to be a problem is #22, which is located in the fuse block under the hood. That fuse feeds power to both the injection-pressure regulator and the brake-pressure switch. If the engine runs fine but intermittently blows that fuse, the brake-pressure switch is often the culprit and probably needs replacing.



Subscribe Today and Save up to 83%!

Subscribe Truck Trend Magazine

Subscribe to:

Truck Trend

Subscribe Diesel Power Magazine

Subscribe to:

Diesel Power

Subscribe Truckin Magazine

Subscribe to: