Welcome to Top Tech Questions. Oftentimes, readers contact us with questions about articles, or to praise us on what a good job we are doing. But our favorite form of reader communication is tech questions. Our Top Tech section is a place where you ask what’s on your mind, and we answer it. Got a trouble code? Wondering how to get your engine to make more power? Send us an email at jason.sands@sorc.com and we’ll do our best to answer it.
| We drive our diesel trucks to work almost every day—so far with no ill effects. Of course, sunny California weather is no match for Midwest winters, but our roads are actually in a lot worse condition out here.
Short-Trip Engine Damage Prevention Question: I have an ’04 Dodge Ram 3500 Quad Cab with an Edge A2 monitor, Juice Attitude, and an Airaid intake. The truck has 3.73 gears, single rear wheels, and I use it to pull a 34-foot fifth-wheel toy hauler. Until now, I’ve only used it for long trips, but now it’s going to be my daily driver. My commute to work is only about 10 miles (each way). Will that be hard on the engine?
Duane Sullivan Newton, Iowa
Answer: You shouldn’t have any problems driving your diesel on short trips as long as you take good care of it—especially in winter. When it’s cold, the oil will be very thick, and you’ll have a lot of oil pressure as a result. When you floor it with cold oil and water in the engine (especially in a modified truck), bad things can happen. We’ve actually heard of a few blown head gaskets because truck owners went full throttle right out of their driveway. Always make sure your vehicle is up to operating temperature (or at least the needle is off of “C”) before you romp on it.
If your plans include lots of short trips, a switch to synthetic oil such as those available from Amsoil, Shell, or Royal Purple is a good idea. Even when it’s cold, it won’t create quite as much oil pressure in the engine, which means you can be a little more liberal with your throttle application on a cold engine.
Plus, because diesels idle at a slower engine speed (when the oil is just beginning to get moving), they have an advantage over gas-powered vehicles because the engine will complete less revolutions in this warm-up stage. Last but not least, there’s no rich air/fuel mixture to contribute to bore wear or oil contamination during the first few minutes of running. While this last item may have mainly been a worry in the old carbureted days, we’d have to say that even on short drives, you’re still better off driving a diesel than a gas vehicle.
I Want My MPG
Question: I have an ’02 Chevrolet 2500HD Crew Cab 4x4 with a Duramax and Allison transmission that has a Banks intake and a Hypertech programmer. Last year, I had to spend more than $8,000 to replace the glow plugs, injectors, fuel pump, and water pump. I had been getting about 16 mpg from mostly city miles before, but after all the repairs, I’m only getting 12 to 13 mpg. It was time to replace most of the fluids, so I decided to change all the fluids over to Royal Purple synthetics, hoping that would improve the fuel mileage—but it didn’t do anything. Is there a reason why I would lose so much fuel economy after changing out all those expensive fueling parts? If anything, I would have predicted an improvement in fuel economy if the injectors were bad. Is there anything that needs to be adjusted to at least return it to my previous mpg? I know there are at least 3 or 4 more mpg in my truck, but I don’t know how to get them back.
Bryan Hiler
South Bend, Indiana
| Duramax-powered Chevys and GMCs are known for getting outstanding fuel economy. In fact, a Duramax-powered truck has won our fuel economy segment every year at the Diesel Power Challenge.
Answer: Pretty much everything in the fuel system you replaced is dumb—that is, it just knows it is supposed to turn on and maintain pressure. The only parts you replaced that would have an impact on fuel economy are your injectors, which are tied into your factory computer. If the dealer has uploaded an updated calibration to your LB7, your fuel mileage can change drastically. We’d start off by taking the truck back to a stock tune and then reloading your Hypertech tuner. Diesels can operate at anywhere from a 20:1 to 100:1 air/fuel ratio with little or no visible smoke, so your air/fuel ratio can radically change without you really noticing (other than the decreased mileage). If re-booting things doesn’t help, the next thing we would try is an economy tuner that is specifically designed for good fuel economy, like the PPE Xcelerator or an EFILive economy tune. The advantage of EFILive is that it allows you to adjust pulse width, rail pressure, and injection timing, so you can tailor a tune (if you know what you’re doing) to give you maximum fuel economy for your style of driving. EFILive also allows the end user to switch between engine calibrations to find which one works best for their model year. If you don’t want to tackle EFILive by yourself, there are support forums, or you can simply purchase a tune from companies like Duramaxtuner.com or Adrenaline Truck Performance.
IDI Power Question: I bought a ’94 Ford F-350 7.3L turbodiesel two years ago. I’d like to know what kind of upgrades I can get for it. I’ve looked on the Internet, and I can’t really find anything due to the age of the truck.
Nathan Ries Via email
| Project 300 is under the knife right now, as its old engine went kaput. But look for it to return to the magazine after a cheap IDI rebuild.
Answer: A lot of people will see the horsepower potential of early ’90s Dodge diesels and buy a Ford—assuming they’ll have similar upgrade potential. Unfortunately, these early Ford indirect-injected diesels (IDI) don’t have much to offer in the form of performance. They’ll last forever and run on almost anything—just don’t expect them to make a bunch of power.
There is a bit of hope, however, at least enough to keep up with the newer trucks (as long as they’re stock). If you turn up the stock Stanadyne injection pump, let a little more boost in, and run water-methanol injection or propane, expect about 200 hp at the rear wheels, which is a good boost. We currently have an IDI Ford project nicknamed Project 300, and it made 123 hp and 244 lb-ft of torque with an ATS turbo kit. Feature Editor Jason Thompson recently found out his IDI has a lot of blow-by and blown head gaskets, so that could be a big reason why his power was lower than hoped for. Look for Project 300 to re-appear in the magazine soon and continue its slow and steady horsepower march.
