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Diesel Tech - You've Got Questions? We've Got Answers!

Top Tech

Bruce W. Smith
Mar 14, 2016
Photographers: Bruce W. Smith
Photo 2/5   |   001 DSLP 160700 TOPT Premium Diesel
In some areas of California, diesel owners can get “premium” diesel with a cetane rating of 75, under the name of Propel HPR (High Performance Renewable). This biomass-based fuel has 40 percent more cetane than regular diesel.
Premium Diesel Fuel
I’ve been a fan and subscriber of Diesel Power since its first issue more than 10 years ago. Is there such a thing as premium diesel fuel? If there is, what's the difference? What evidence should I look for at the pump?
Gary Speelman
-via email
Yes, there is a premium pump diesel, and it’s sold in, of all places, California. Propel offers Diesel HPR (High Performance Renewable) fuel at its distributors around the San Francisco Bay area and Central California. This biomass-derived fuel has a cetane rating (CN) of 75, which is 40 percent higher than regular diesel. HPR is sulfur-free and virtually odorless. In essence, it’s “premium” pump diesel. The rating is labeled right at the pump just like gasoline. Diesel fuel’s cetane rating is an indicator of how fast the fuel ignites under extreme pressure; the higher the number, the shorter the delay between the time diesel enters the cylinder and ignition. A faster burn means a more efficient burn. A higher cetane rating also improves cold weather start-ups and reduces emissions. On the whole, however, we don’t have very good diesel on this side of the Atlantic Ocean. Most pickups in the United States are designed to operate on petroleum-based, ultra-low-sulfur diesel, which has a minimum cetane rating of 40 out of a possible 100 (European diesel is rated at 51). U.S. Biodiesel’s (B100) CN is also 40. The highest grade is synthetic diesel, which can have a cetane rating anywhere from 60 to 80. If you can’t find premium diesel in your area, the other way to give the cetane in your truck’s tank a boost is to use an additive such as XDP’s Diesel Power Plus, Hot Shot’s Diesel Extreme, or Amsoil’s Diesel Cetane Boost. Such products can typically up the rating number by two to seven points, depending on the dosage.
Fuse Blowing Non-Starter
What would make the 30-amp fuse in my ’99 Ford F-350 keep blowing when I try to start its 7.3L engine? My truck is bone stock, and I’ve never had this kind of problem before. The fuse is the second one from the bottom on the right side of the fuse box.
Chris Livingston
-via email
The most likely cause of the fuse blowing is a bad fuel-heater element, which is located in the bottom of the filter housing. Unplug the heater’s connector at the back of the fuel filter housing. Replace the blown fuse, and the engine should start right up. If it starts, then you can decide whether the heater element needs replacing. In moderate climates, it’s not really necessary. If unplugging the fuel heater doesn’t solve the problem, then you’ll need to run a troubleshooting diagnostic on each of the other components that also draw power from that fuse (that 30-amp fuse controls the PCM relay coil, injector-drive module, and wastegate solenoid).
Photo 3/5   |   002 DSLP 160700 TOPT CAI MAF
MAF sensors on turbodiesels are extremely sensitive to changes in airflow. Installing a freer-flowing performance air filter or complete cold-air intake system (CAI) will affect how the MAF perceives that higher flow.
P0101s & CAIs
I've been hearing/reading some not-so-good things about K&N air filters (specifically on turbodiesel engines) and wanted your opinion on its product. I use a K&N drop-in air filter on my Chevrolet Cruze diesel and in every other vehicle I own with the exception of my ’09 Dodge Ram 2500 (with a 6.7L Cummins engine) that has an Airaid CAI installed. I clean and re-oil the filters regularly and have accumulated hundreds of thousands of miles without issue. Can you shed some light on this somewhat controversial subject for me?
Rick in Maryland
-via email
In a nutshell, MAF sensors on turbodiesel engines are extremely sensitive to changes in airflow. So, installing a freer-flowing performance air filter or complete cold-air-intake system (CAI) will have an effect on the MAF sensor and the way it processes that higher flow and the turbulence/vortices the filter creates. Some MAF sensors are more sensitive than others. When the MAF sensor gets hit by changes in airflow that are outside of its very narrow factory parameters, it triggers a diagnostic trouble code (DTC-P0101) because the ECM thinks something is wrong with the sensor. But, even if a code isn’t thrown, the change in airflow around the MAF can result in poor engine performance, rough idle, and other issues related to air delivery. This is why many aftermarket engine programmers have special tunes designed to work with specific aftermarket CAI systems.
Hot Ram Coding What could cause a “P051” diagnostic trouble code (crankcase pressure sensor circuit range/performance) on my ’10 Dodge Ram? The truck has a 6.7L Cummins engine.
Shawn H.
-via email
The crankcase pressure sensor circuit range/performance code you see is most likely related to the closed crankcase ventilation (CCV) filter being saturated to the point of creating restriction in the system. The Cummins 6.7L’s CCV system dumps crankcase gasses into the turbocharger inlet “post filter” in order to help reduce emissions. The owner’s manual says the CCV needs replacing at 67,500 miles, and that’s the odometer reading when the computer will throw the type of warning you’re seeing. Sometimes the computer will also trip related codes such as a P051B. Changing the CCV filter should resolve the code issue. Some owners convert their 6.7L’s CCV back to an open breather using an open breather kit, which eliminates the filter, stops oil buildup on the turbo compressor, and keeps the intercooler clean.
Photo 4/5   |   ACP 0980kits Three
Photo 5/5   |   003 DSLP 160700 TOPT Blackstone Analysis Kit
When engine health is a concern, get in the habit of having an oil analysis done on a regularly scheduled basis. It’s similar to people having blood tests done during annual physicals, heading off unseen problems before they catch us by surprise.
Aluminum in Oil Filter
I’ve changed my ’10 Ford F-350’s 6.4L engine’s oil and filters two times since doing a major repair, and each time I’ve found tiny specks of what appear to be aluminum the size of a sharp pencil tip in the filters. I bought the truck with a damaged camshaft and lifter on one cylinder. I installed new lifters, a cam, bearings, and an oil pump and replaced a damaged piston and valves with new ones. Finding aluminum specks in the oil filters concerns me that something else is wearing very quickly. What could the problem be?
Todd G.
-via the Internet
Any metal fragments or large specks in the oil filter are not good things, so worry is well-founded. Pistons and the oil pump are the two parts that are subject to showing aluminum wear. But, before thinking the worst, one possibility is that the filter is catching metal fragments from the previous parts failure, which may still be lurking around inside the engine. For peace of mind, order an oil-test kit from a lab such as SGS Herguth Laboratories (herguth.com) or Blackstone Labs (blackstone-labs.com) and have a sample of your engine’s oil analyzed ASAP. That way, you can have a much better idea of if/where a potentially serious wear problem exists.
Hard-Loping 7.3L
My ’02 Ford F-250 Lariat’s 7.3L engine starts then idles like a muscle car with a huge cam in it. Then, after 30 seconds or so, it dies. The engine sputters when I apply throttle but smooths out above 1,000 rpm or when the transmission is put in gear. I changed the ICP and CPS but got no codes and experienced the same problem. The loping idle is driving me crazy!
George Rankin
-via the Internet
As with many engine-related issues, figuring out exactly what is causing a rough idle problem usually requires running diagnostics in a shop setting. But we passed along your description of the issue to our Ford experts at both Scheid Diesel Service (scheiddiesel.com) and Mobile Diesel Service (mobiledieselservicellc.net) to see what explanation they might offer without seeing your truck in person. Both came to the same general consensus about the lope: If it only happens when the engine is cold, it’s likely a problem with the injectors. If it doesn't go away after the engine warms up, it could be a fuel delivery problem or maybe even an injector sealing problem.
Scheid’s resident Ford expert, Dan Vogel, says ’99-to-’03 7.3Ls are notorious for connector and continuity issues with the under valve cover (UVC) wiring harnesses. If you haven’t run a resistance check with a multimeter between the injector driver module (IDM) and the wiring to each of the injectors or replaced those molded harnesses, now might be a good time to do so. Again, the best way to get right to the heart of the issue is have a good technician run diagnostic tests.

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