Diesel Tech Questions
You've Got Questions? We've Got Answers!
Low-Stall ConverterI installed a VE-pumped ’93 12-valve 5.9L Cummins engine in my ’87 Dodge Ramcharger. The transmission is a non-lockup A518 (46RH) four-speed automatic. The engine is mostly stock, other than a smidge (an actual unit of measure, at least in Ohio) of added timing, a moderate turn of the fuel screw, and a Holset HE-341 turbocharger from an ’03 Dodge Ram. The Ramcharger is outfitted with locked 1-ton axles, 4.10 gears, and 37-inch tires. Total rolling weight is a tick (another official unit of Ohio measure) under 6,000 pounds. It’ll be used for light trailer towing (less than 5,000 pounds), general daily driving, backcountry camping trips, and moderate off-road use. My question concerns the 46RH’s torque converter. It's my understanding the stocker is a bit on the loose side, with a stall of around 1,900 rpm in a first-generation Dodge Ram. With my setup and more-efficient-than-stock turbo, I'm told I'll be happier with a lower-stall converter. Your thoughts?
Transmission specialist Ondra Terry at TCI Automotive says he has never heard of the 46RH Dodge Ram converter being “sloppy” but tells us the stock stall usually ranges between 1,800 and 2,000 rpm, and your setup will definitely benefit from a lower-stall converter. He says TCI doesn’t have a specified part number for a non-lockup 46RH converter.
However, Ondra offers this solution: “What we’d do is use our PN 142261, which is a lockup converter, and then custom-build it to non-lockup specifications with an estimated stall speed between 1,300 and 1,500 rpm. Doing this will reduce transmission temperature at least 10 degrees by reducing slippage in the converter, give your Cummins-powered Ramcharger better fuel economy, and reduce engine speed.”
Wait to Start TripSo I have an ’06 Dodge Ram 3500 with an Edge Products EZ Module, 62mm turbocharger, AirDog fuel system, K&N Engineering cold-air intake, and Banks Power High Ram on it. While driving down the highway with cruise control set at 65 to 70 mph, all of a sudden my “Wait to Start” warning message comes on and the chime dings 10 times. I let off the throttle and drop the speed a little, and the warning goes away after a few seconds. On Level 1, it happens once. But on Level 2, the problem happens more frequently. The diagnostic-trouble codes are P1222 and P1223. I have Auto Meter EGT, transmission, and boost gauges. The boost gauge works, and the EGT is good to 400 degrees. After that, the needle just drops. When I turn the lights on, it will go to a random number and stay there. So, my two questions are: Why is the EGT gauge so erratic, and why does the “Wait to Start” warning come on randomly and the chime ding 10 times?
We suspect the gauge issue is due to a wiring or sending-unit issue. When the “Wait to Start” warning message illuminates and the seatbelt chime dings 10 times, P1222 (leak detected during motoring) or P1223 (leak detected) diagnostic trouble codes are triggered. Oregon Fuel Injections’ Mark Gotchall says,“The P1223 is usually caused by excessive return from the injectors or a bad feed tube to an injector connection. The P1222 during cruise can indicate a bad fuel-control actuator.”
Mark also says ECM recalibrations sometimes make the fuel-return issue worse because of increased rail pressure. But this is a calculated code set by Ram engineers that looks at several parameters—not just one sensor. The condition can also be brought about by a poorly executed ECM reflash.
Dual BatteriesI have an ’04 GMC Sierra 2500HD. It’s my first diesel truck, and I love it. I looked under the hood. What is the purpose of having two batteries?
“Why two batteries?” It’s a question most first-time diesel pickup owners ask when they open their truck’s hood. Diesel engines have nearly double the compression of a gasoline engine (17:1 compared to 8.5-9:1 found in most of today’s gas engines.) Their internal rotating components (such parts as the crankshaft, connecting rods, and pistons) are also more robust. The diesel’s higher compression and greater rotating mass requires a lot more battery power, called “cranking amps,” for its starter to effectively spin the engine.
The dual-battery setup in a diesel, where the two batteries are wired in parallel (negative to negative, positive to positive), provides double the available cranking amps of a single battery of equal size. Basically, what you have is twice as many lead-acid plates providing the cranking power, all the while keeping the system at 12 volts.
In addition to supporting all the truck’s electrical components and spinning the starter fast enough for it to fire the engine, the batteries also power eight glow plugs that preheat the combustion chambers before starting. It’s all a massive load on the 12-volt electrical system. Some engines also have grid heaters to warm up the air going into the intake, and some have fuel heaters. They’re all high-amp-draw components. Cold weather also makes the electrical loads on the batteries even greater, so diesel truck manufacturers provide the necessary cranking power for cold climates by doubling up the batteries.
Another advantage of two batteries wired in parallel is their life is actually extended because they take less of a hit at each start-up than a single battery does. (Batteries tend to last a lot longer when they are drawn down a little, then charged back to 100 percent, which is what happens in a dual-battery diesel application.) All are reasons why you rarely see single batteries under the hood of diesel-powered pickup trucks.
Using Fuel AdditivesDo you recommend using fuel additives? I still drive my 5.9L Cummins-powered ’94 Dodge Ram , and at 100,000 miles, my senior Cummins mechanic in Grand Rapids, Michigan, set the valves and told me to use Stanadyne Performance Formula. Since the reduction for diesel fuel to 15 parts-per-million sulfur (from 600 ppm for years), the technician says he’s performing very expensive repairs on fuel systems in modern, over-the-road common-rail engines, which he attributes to the loss of lubricity in clean diesel fuel. So I use the additive in my Dodge and my ’13 (now-condemned) Volkswagen Passat TDI. Comments?
Jim in Michigan
The short answer is, yes. Using a diesel-fuel additive is good for both preventive maintenance and enhancing overall performance on older rigs and new trucks, because there’s a wide fluctuation in cetane ratings and the overall quality of today’s diesel fuels. We asked a couple of our diesel fuel-injection experts for their take on the matter.
Alec Hembury at Industrial Injection Diesel Performance in Salt Lake City, Utah, recommends every diesel owner run a fuel additive. “Absolutely! Our Deuce Juice Fuel Additive adds lubricity to the fuel system that low-sulfur fuel has taken away. That added lubricity increases fuel components’ life from 15 to 50 percent, and it improves reliability as well as performance since the injection system’s components can run smoother. Adding cetane to the fuel helps it burn hotter, which increases power and fuel mileage. In addition to increasing lubricity and cetane, Deuce Juice cleans and disperses any water that may get in the fuel system.”
Mark Gotchall at Oregon Fuel Injection in Eugene, Oregon, says, “We recommend Stanadyne Fuel Additives’ Performance Formula. We have used it regularly for many years, and the wear we see in mechanical-injection pumps is about 50 percent less than when no additive is used (it looks like 80,000 miles, not 120,000 miles). We see some instances of low lubricity, but I wouldn't say it is a rampant issue that causes short-life failures. With that being said, fuel quality varies from area to area across the U.S., and even from the same service station. Consider a [diesel-fuel additive] as ‘insurance’ against low-lubricity fuel. We also recommend it for new vehicles. With the cetane boost, you will get a better burn, which means less smoke and more power. Less smoke means fewer particulates, and that equates to fewer regeneration cycles and better mileage in DPF-equipped vehicles.”
Programming for MPGI have been researching the Duramileage EZ Tuner programmer. It can reportedly increase fuel mileage by 4 to 7 mpg. Have you tested these? I’m also looking at the Edge Products Insight Pro CTS 2. I want more fuel economy, rather than a ton of power for my truck’s 6.6L Duramax LML engine. I only tow about 7,000 pounds.
I had an ’08 GMC Sierra 3500HD dualie tuned with a Hypertech Max Energy programmer. The truck, set on 35-inch tires and a 6-inch lift, gained 2 mpg over stock while cruising on flat interstate at 70 mph. However, fuel economy dropped more than it did in stock mode whenever the newfound power was called upon. That’s going to be the general result with all programmers on the market, regardless of brand. The reason is simple: Fuel and timing are the primary elements of making power with a diesel.
Aftermarket tuners spend hundreds—if not thousands—of hours using dynos and computers to manipulate fuel-injector pulse widths, making them longer or shorter than stock parameters at any point along the power curve, to suit a specific goal. That goal can be improving “economy” or “power” at whatever rpm. They pay very close attention to the fuel-to-power ratio, brake-specific fuel consumption, and exhaust gas temperature. When BSFC reaches a point of diminishing return or EGT endangers engine longevity, the tuners back down the amount of fuel and adjust timing before moving on to the next point in the rpm band that they want to change.
One change many calibrators make to increase fuel economy is target light-throttle, steady-state driving situations, similar to those you experience while cruising down the highway. In such instances, they typically shorten the injector pulse width (less fuel) and adjust timing as much as possible during that specific point in throttle position, engine rpm, and vehicle speed, hence the potential gain in mpg over factory.
However, most tunes are installed because the diesel owner wants more pulling power. More power is the direct result of more fuel being dumped into the cylinders. An aggressive right foot will quickly nullify any fuel-economy gains a tune brings during steady-state cruising.