Keeping Flexible with New Electronics

Flex fuel and clean diesel engines are helping to reduce emissions, noise and fuel costs for fleets, but that also means more things to worry about. New electronic controls are important parts of these new technologies, so your technicians need to be up to speed on how to troubleshoot and fix these systems.

Flexible fuel vehicles can run either on gasoline or blends of up to 85 percent ethanol and are very similar to regular gasoline-only vehicles, with only a few changes to the engine and fuel systems. These flex-fuel vehicles have been around for a few decades, and today there are dozens of different models to choose from.

GM Powertrain BioFuels manager Coleman Jones says fleet interest in flex fuel vehicles has picked up recently, as many fleets are calling for them in their statement of requirements. With these vehicles come some new controls that technicians need to understand, though.


One change is the sensors that make sure the ethanol-gasoline blend is appropriate. Jones says GM previously used a physical flex fuel sensor to measure fuel capacitance and composition, but introduced a “virtual” replacement in 2006.

“It uses the oxygen sensor and the fuel tank level sensor to calculate the fuel in the fuel tank and it also calculates the composition of the fuel you put into the fuel tank,” he says. “It’s what we call a rationality check—the technician can read what the vehicle thinks it’s burning and we have a tool that allows you to actually determine the ethanol content of the fuel sample if you pulled it out of the tank. One of your service procedures is to compare what your vehicle thinks it’s is burning versus what it is burning.”

Another potential issue for techs to be aware of is the disparity between the various mixtures of ethanol and gasoline, despite what may be advertised. Jones says fleet managers need to know exactly what they are putting in their vehicles.

“When we introduced this we assumed that the only fuel sold in the U.S. would be fuel that meets specifications for E85, and it turned out to be wrong,” he says. “(Misidentified fuel is) out there and we have to deal with it.”

To help mitigate the problem, GM released a software update last year for vehicles with older software, such as pick-ups and utility trucks.

“(Otherwise, if) you took one of these vehicles that has this older software and fueled it with E20 or E60, it would not compute, which doesn’t mean you would immediately set a (warning) code, but you might,” Jones says. “So there is a service action out there, so if the vehicle goes into the dealer for any reason, they’ll get the update. If you get a car coming in that shows a typically lean bank one or lean bank two code, you ask the driver if he’s been running E85 and then you might want to check to see if the fuel in the fuel tank matches what the controller thinks it’s burning. We don’t see it very often; we’re just being proactive. This is what you’re going to see in the future.”


For fleets without flex-fuel vehicles, Chicago-based Flex Fuel U.S. sells a “Flex Box” that allows gasoline-powered vehicles to run on E85. Their ethanol conversion system was recently certified by the EPA—the first such system to receive that status after more than two decades of attempts by the industry, says company president Mitch Sremac.

“Fleets are always concerned with insurance and OEM warranties, so they’ve never been willing to put a kit in a car because they weren’t street legal,” he says.

With federal laws mandating commercial fleets with more than 50 vehicles to have a certain percentage run on alternative fuels, Sremac hopes the certification gives his company a leg up on the competition.

“A lot of fleet people have been calling us and asking about the system,” Sremac says. “Because of that requirement, guys have gone out and spent money on LPG (liquefied petroleum gas) and CNG (compressed natural gas) kits. Well, LPG is a $5,000 conversion and CNG is about $8,000. Our kit you can have installed for about $1,200 and it doesn’t take up any space. You can run gasoline or ethanol, whatever you have.”

The system makes converting fleet vehicles to E85 a long-term cost-saver, Sremac says.

“First of all, there’s the (reduced) cost of fuel—E85 is around 50 cents a gallon cheaper than gasoline in the Midwest,” he says. “There’s always been this stigma that you lose 25 or 30 percent fuel economy with E85, and we found you get anywhere from 0-5 percent loss, and we have that on our emissions testing. If you’re putting on 25,000 miles a year, you’ve paid for that kit in the first year.”

With many states offering incentive programs to “green” fleets, the cost could be even less.

“You could put a kit on in the state of Illinois and you’d get an 80 percent rebate back,” Sremac says. “You’d probably get a return on your investment in about two months.”

The company invested more than a million dollars in the system, including certifying each vehicle model as required by the EPA.

“For us to certify 80 percent of the fleets out there, we have to go in and certify 30 different models,” he says. “You have to be able to keep a certain emission level for 100,000-plus miles, so it’s very complicated, very difficult and very expensive.”


The Flex Fuel U.S. system looks quite simple, with a processor, injector, alcohol and flex fuel sensors, as well as other sensors that connect to the engine. It’s designed that way so technicians can install it without problems, Sremac says, and troubleshooting is also supposed to be basic.

“If something goes wrong with the system, the car’s either going to go rich or lean, depending on whether you’re running gasoline or ethanol, so you would automatically get a check engine light,” he says. “So if you kick off a light, you bring it into your technician and he plugs in an OBD-II scanner and he sees it’s too lean or rich, you know maybe there’s something wrong with the system.

“And then you can go check it and see if there’s power, and you can take one of those little noid lights and plug it right into one of the test ports we have to make sure the light is flicking on and off to make sure the injector is working,” he says. “There are ways to check the system out; it’s not very complicated.”


Curtis Lacy, president of marketing and distribution for the Boise, ID-based Full Flex International, said the relatively low cost of ethanol conversion systems like theirs can help fleets save serious cash.

“If you want to convert to CNG or LPG, you’re looking at anywhere from $1,500 to maybe $15,000, depending on the vehicle,” Lacy says. “With our system, you can convert from anywhere from $350 to under $500, depending on the size of your engine. And the conversion time takes 15-20 minutes. It’s a lot easier solution than buying a whole new fleet of vehicles.”

Lacy says the system’s cold start feature is another advantage for fleets that operate in freezing temperatures.

“Ethanol is water-based so it makes it kind of funny in the winter to startup, but our cold start senses the different temperatures and will make necessary adjustments to bring in more fuel or to help warm the fuel up from the engine, so when you start the vehicle, it starts with no problem,” Lacy says.

Full Flex will fly its staff around North America to train technicians how to properly install and maintain the systems, though Lacy says there is not much to know outside of being able to understand an electronic code reader.

“If you can change your oil, you can install this,” he says.


Higher quality diesel fuel, advanced engines and better emission controls have brought “clean diesel” to many fleets, and new technologies have made diesel engines cleaner, quieter and more powerful. The electronic controls on these engines are also more sophisticated, with computers controlling the amount of fuel that flows from the injector.

Donn Frincke, assistant chief engineer for GM’s Duramax engine, says the 2007 emission standards prompted the company to tweak its electronic control system just a bit.

“It was primarily a refinement of the control algorithms and the calibration,” he says. “The big change for 2007 is this diesel particulate filter. The particles of soot get trapped in the walls and then periodically we go through a process called regeneration in order to incinerate that soot, and it burns it up and turns it into harmless gases. So the basics of the engine control system were there—we had to make some slight modifications to them in order to carry out this regeneration process.”

To avoid unnecessary maintenance issues, Frincke says if your fleet uses Duramax or other “clean diesel” engines, using the specified fuel—ultra-low sulfur diesel—and oil is essential.

“(Ultra-low sulfur diesel) has a maximum amount of sulfur—15 parts per million—and the previous generations over diesel had 500 parts per million,” he says.

Frincke says CJ-4 engine oil is also preferred in clean diesels because it burns less frequently, so less ash will collect in the particulate filters.

Ed English, vice-president and technical director for Flowery Branch, GA-based Fuel Quality Services, Inc., says electronic systems on older engines will not be as sensitive to lower or higher sulfur issues as compared to new models.

“That’s been borne out in discussions I’ve had with folks involved in the military, where they have diesel engines designed to run on JP-8, which is a high sulfur concentration,” he says. “Some of their newer engines that meet the new mission control standards, tend to have problems running on JP-8.”

Since the new ultra-low sulfur fuel is more stable than its predecessor, there should not be problems with fuel quality or variability, he says.

“With low sulfur diesel, there was some variability as far as stability, and that could have been giving some of the maintenance folks some problems with reliability and consistency,” he says.


While fleets might be moving toward more flex-fuel and clean diesel vehicles, the maintenance challenges for technicians remain about the same; with a few changes. Understanding electronics and computers is still the bottom line.

Like most parts of a vehicle, flex-fuel and clean diesel engines are becoming more computerized and more sophisticated. Without physical sensors to measure fuel capacitance, technicians who used to rely on the “hands-on” approach will need to understand how new virtual sensors work and how to use them to locate and fix the inevitable trouble spots.

Knowing a vehicle’s software and being able to properly use scanners is the best way to keep on top of maintenance issues. If your technicians are up to speed on these tools and procedures, and are making sure your vehicles are running on the right blend of fuel, it will help keep your vehicles out of the shop and keep them rolling down the road and making you money for as long as possible.