Are you a car junkie? Is there a hot rod parked in your garage or a racecar on a trailer in your driveway? Do you drool over the latest issue of Hot Rod magazine?
If you do, you're not alone. Many of your customers are just as high on high performance as you are, and while all the fundamentals of "go fast" are still the same, how you apply them has gotten pretty high-tech.
I grew up in the "muscle car" era, and even though the engines that Detroit produced were "ground pounders," they were far from polished. That was a good thing for the young speed junkie. In those days, it was simply a matter of making the engine breathe better and burn the fuel more efficiently.
We added larger carburetors with bigger jetting to take advantage of the high lift camshafts and high compression pistons we were installing inside. We mated the intake and exhaust to the port openings on the cylinder head, and took the time to make sure all the casting marks and roughness in the passageways were polished clean and smooth. The gasses we now had sliding easily in and out were given a wide-open path to the atmosphere by ditching any catalytic converters we may have been cursed with, preferring a good set of headers and dual 3-inch plumbing to dump the fumes just past the rear bumper — the contents of which we weren't overly concerned with, since we didn't have emissions tests to pass anyway.
It's a lot different today. Since that time, automakers have responded to the need for improved fuel economy and emissions by designing powerplants that are much more efficient — and managing them with electronic control systems that rival the computing power of most home PCs. In-line four-cylinder engines are rivaling the horsepower outputs of much larger engines of the past.
So, what is a modern-day enthusiast to do?
If there is one fundamental rule in pushing the performance of any engine, it is to pack as much air into it as you can. By adding more air, you can add more fuel — and the two combine to increase the power produced in a given displacement.
Shawn Sexton is the owner of Street Sports, Inc. His shop, based in Lexington, Ky., has been modifying cars and light trucks since 1993. He notes that the engines rolling off today's original equipment manufacturer (OEM) assembly lines are, for the most part, already highly tuned and require little improvement to their internal components. The fundamental adage of packing in more air is handled by the addition of an aftermarket turbocharger or supercharger. The exhaust is also opened up to make way for that additional air to get out again.
Now that wouldn't be a problem in the pre-electronic engine management era. It was a simple matter of adjusting the jetting of a carburetor to maintain the proper air/fuel mix, and playing with ignition timing by rotating the distributor. With a computer in control of fuel and ignition, though, tuners' hands are tied when it comes to adjusting these parameters.
"In the early days of performance tuning," says Sexton, "we couldn't do much to the cars. We could prep the cars, install the accessories, but we then had to send off the computer for modification."
According to Sexton, some of the early modifications required removal of the OE control module's processor, and the installation of a socket in its place that allowed a new processor to be plugged in. Other early attempts at performance tuning used resistors supplied by an aftermarket specialty company that were added in series with certain engine control module (ECM) input circuits — effectively lying to the ECM about what these sensors were actually seeing.
"We were telling the ECM that it was colder than it really was so it would add more fuel," Sexton explains. "But it added fuel across the rpm/load range and skewed fuel trims to the point where we had to periodically reset the KAM (keep alive memory) to restore drivability. It also caused problems when we had to diagnose a real fault. The scan data PIDs (parameter identifiers) were fiction."
Aaron Chapman is the technical support manager for Edge Products, a leading producer of performance kits for a variety of applications for both gas and diesel engines. "Programming has come a long way in just the last few years," Chapman says. "It used to be that you'd install an in-line module that simply skewed the factory sensor readings going to the OE control module."
Sexton remembers those days. "The 'add-on' modules provided some tuning capability over certain parameters, but these, too, were still simply modified inputs to the OE module to make the ECM see what we wanted it to see. The advantage of some, however, was the addition of a jumper harness that we could install in place of the aftermarket unit to easily restore a normal data stream to the ECM when we needed to perform traditional troubleshooting."
"Today, it's one of two things," Sexton says. "We can install a complete 'plug-and-play' replacement computer that takes the place of the OE unit, most of which can be reprogrammed for the modifications that have been made to the car. But in most late-model cars — over the last 10 years or so — the OE module itself can be reprogrammed. The first ones we've done were Subarus. We have WRX customers who are running on the street during the week, then hitting the drag strip on the weekend and posting runs in the 10s without changing anything on the car, including the tires."
"With current technology, we can go in and make some drastic changes to the software itself, with the resulting drastic changes in engine performance." says Chapman. "Now we can really define what we're using the vehicle for. In the case of our Jeep kit, we maximize the performance based on use, whether it's a daily driver and you're looking for fuel economy, or it's your off-road rig you're heading off to Moab with."
The kit Chapman refers to is marketed for the Jeep 4.0, and includes a cold air intake, new throttle body and programmer.
"It's kind of a traditional concept," Chapman says. "Opening things up, getting the engine to breathe a little better. The OE throttle body uses a tapered bore. The top of the throttle body measures 52mm and opens up to 54mm."
The replacement included with this particular kit uses a straight bore design that is 62mm in size. But no additional benefit would be realized unless you could remap the ignition and fuel curves in the control module itself, he notes. That's where the handheld programmer that comes with the kit comes into play.
"The FlashPaq programmer plugs into the DLC (diagnostic link connector), and it reprograms the software to remap the fueling and ignition timing strategies to compensate for the additional air that has been added," Chapman explains. "The combination of more air and more fuel results in more torque and horsepower."
We asked Edge Products' Chapman to walk us through a typical reprogramming using the FlashPaq. (Author's Note: This is only one example of performance reprogramming and is different from performing an OE reflash. Be sure to fully understand the procedures required before trying this on a customer's car.)
"The first step after installing the new hard parts is to connect the programmer to the DLC and turn it on. The first screen you'll see is a pop-up menu that is basically going to ask you what you want to do, what performance level you want and what your vehicle specifics are," he says. "Before our tool will begin to rewrite data, it is going to back up the original data first. Once that step is completed, the files will be stored in the tool in case you ever want to put the car back to a stock configuration. Then, depending on the individual kit, the tool will walk you through a series of selections to fine-tune your preferences. Finally, and once all the selections have been made, the tool will ask if you are sure you want to proceed. The actual reprogramming typically takes less than five minutes."
What is included in the various selections? Chapman says that typically, Edge Products offers options related to fuel.
"We'll have different strategies based on the user selecting to use 87 octane, 89 octane or 91 octane," he continues. "You go in and select what fuel you will be running, and in some cases, we'll also offer additional customization based on desired use. In the Jeep's case, depending on the application, it will allow you to modify shift parameters in addition to the engine management strategies."
If you've performed reprogramming in the past, you know that maintaining the communications link between the vehicle and the tool can be critical. A stable battery voltage is needed, and other conditions may need to be met, to avoid problems.
"Some GM Duramax trucks, for example, often need to have the radio fuse removed while programming because the steering wheel audio controls use the CAN (controller area network) bus to communicate with the radio, and that interferes with the reprogramming," Chapman says. In the case of the Superchips tool, there are additional safety nets built in to ensure that a loss of communication between the tool and the car does not result in an irrecoverable ECM.
It is also interesting to note that the reprogramming tool supplied acts as a Global OBD II scan tool that is capable of reading and clearing codes, as well as several other OBD II generic functions.
"We spend a lot of time testing to determine different optimum settings so all the installer has to do is input his or her choices in an 'A, B or C' kind of format," Chapman explains. "However, many of our products (the Evolution line) allow a variety of custom parameters the installer can select from, like what tire size he's using, the final drive gear ratio installed in the car, individual shift points and firmness — even injector timing."
As Sexton points out, most of today's cars have a little "fudge factor" built in.
"Performance modifications to the OE mapping are needed to take advantage of the actual modifications made to the engine," Sexton adds. "And when modifications are made, and that fudge factor is removed, it becomes imperative that the owner uses the recommended fuel and take care of the car's (normal maintenance)."
What about the popularity of dyno tuning?
"These days, almost everyone is asking for dyno tuning," notes Sexton. "The sad thing is, they really don't understand why. It's just that they've read it in the magazines. So their mindset is that the dyno makes the car go fast. But the reality, of course, is that the dyno is nothing if there is nothing that we can tune on the car. Contrary to what some customers think, a dyno is not a tool that you can connect to the OBD II DLC, push a button to select what type of performance you want and then walk away. The dyno is a tool, and is only as good as the person who is operating the tool."
The dyno is a way to operate the vehicle under a variety of loads and speeds to do what we used to do a quarter-mile at a time: Dial in the parameters that maximized power output. We did it by reading spark plugs and noting the changes in our elapsed times. Today, it's done from the front seat of a stationary car with a PC in your lap.
To learn more about high-performance tuning an EFI car, Sexton recommends visiting EFI University at