Pros Tips to Preventing Pitfalls when upgrading to EFI
New technology can take a while to be accepted in any industry or hobby. But when it comes to classic cars and hot rodding, aftermarket EFI took a while to be fully embraced. Today however, hot rodders seem to welcome EFI with open arms.
There are a number of reasons for the increased acceptance of EFI. On the consumer side, it’s safe to say that people are a little more tech savvy these days thanks to their cell phones or tablets, so the thought of scrolling through a touchscreen to set up your engine’s parameters isn’t as intimidating as it was a few years ago. Also, on the manufacturer side of things, most EFI companies have really made strides in improving their customer interface to ease the initial setup and tuning of their systems.
Another factor is that fuel injection seems to handle modern fuel blends better than a carb. And that EFI accepts elevation and temperature changes better, delivers consistent cold starts and adjusts for boosted applications.
Regardless of the reasons, EFI is more prevalent than ever in hot rodding, though we feel there is still a strong case to the simplicity of a carburetor setup. It is important to remember though, that EFI functions as good as the sum of its supporting parts. You can buy the best throttle body or port fuel induction setup, but if you don’t have the proper fuel delivery or electrical system dialed in to support the EFI, then you’re in for issues, tedious troubleshooting and likely a very poor EFI experience.
In speaking with a number of enthusiasts and companies that have made the swap to EFI, we wanted to share a few tips so you can be prepared to get your system installed completely and properly. The EFI manufacturers are absolutely right in stating that their systems are easy to install with hand tools and can be done in your garage. We reached out to learn some of the common mistakes people make when switching to EFI and gathered some useful tidbits to share so you can successfully install and enjoy the benefits of electronic fuel injection.
Choosing an EFI System
There is pretty much an EFI system for everything out there these days ranging from throttle bodies that bolt in place of a carburetor to complete intake induction kits for popular engines. On the higher end of the scale are those cool individual runner setups modeled after vintage race cars but now have with modern driveability thanks to EFI.
No matter which system you choose, they all have similarities in how they operate. All EFI systems require high fuel pressure, typically 40-60 psi, they all need feedback from sensors such as a wide-band oxygen sensor, Manifold Absolute Pressure (MAP), Coolant Temp, Throttle Position Sensor (TPS), Intake Air Temp (IAT) and others. And, they all need to be wired correctly and have the support of a good electrical system. Any EFI system needs to be carefully wired and will of course require a modified fuel system including an electric fuel pump to support the required fuel pressure.
When it comes to choosing an EFI system, it is recommended to stick with one manufacturer for as much as possible. That way you know the parts are designed to work together – and if you do need tech help, you have only one place to call!
DIY Tuning or Pay to Play?
Another thing to consider when selecting an EFI system is to think about your own tuning capabilities and limitations. There are plenty of “easy to setup” systems available but if you’re intimidated by wiring or a touch screen prompting you to put in engine data, then you best have a knowledgeable friend or a reputable tuner in the neighborhood.
Most performance street EFI systems are much easier to set up today and perform better than 10 years ago, but they really just scratch the surface of what a higher level EFI system is capable of delivering. If you have the budget to work with an EFI Tuner/Specialist, going with the higher level systems can have its benefits.
Dave Ehrlich of Autotrend EFI explained, “I hear people say they don’t need a more expensive racing system with all the bells and whistles because it’s only a street car. But in reality, those bells and whistles are more important on the street to achieve proper tuning and drivability.”
When it comes to the initial calibration and advanced tuning, do you have the knowledge or access to an experienced tuner that can help adjust and tweak the advanced tuning capabilities of a higher-end EFI? Or, is a touchscreen more in your wheelhouse that allows you easily select and set a few parameters yourself then hit the road?
WIRING
Even if wiring isn’t your cup of tea, you should be able to get through a TBI installation. Most street EFI systems are designed with plug-in connectors to the sensors leaving only a few loose wires to connect. Late model engines require a much larger harness with many more connectors including eight coils, eight injectors and even more sensors, however everything is typically labeled and designed with matching connectors. If you read the instructions, lay the harness out to get familiar with the connections and locations, you’ll get through it.
It’s safe to say that most electrical issues do not come from the sensors and plug-in connectors, but rather when it comes down to the loose wires, power connections and the condition of your car’s electrical system overall. This is where you really need to pay attention, review what you’re working with and take the time to do the job right the first time. Poor connections, low voltage, interference and inferior grounds will result in intermittent gremlins and poor performance that will have you bamboozled!
Wiring starts at the battery and all the EFI companies want their ECU connected straight to the battery posts, positive and ground. The battery provides a stable power supply for the ECU and helps act as a filter so the ECU receives the best voltage power source available. That said, do not pile on five or six different connections on each terminal, make sure to use quality terminals and a professional crimp tool.
The battery itself must be in good condition it must have an alternator capable of keeping the battery charged to capacity with the added loads of the ECU and electric fuel pump. If you’re using a 60-amp original style alternator still, it is time to update. According to FiTech, fuel injection can draw up to 20-amps and combine that with the electric fuel pump and you’re already getting close to 40- or 50-amps. This is something many people do not consider and will result in issues. If the charging system can’t keep up, the EFI will suffer and so will you![/caption]
Another often overlooked wiring mistake stems from the keyed 12-volt wiring responsible for turning the system on and off. FiTech explained the importance of locating a connection that not only provides 12 volts when the key is turned on, but it also must continue that solid 12-volts during cranking. In many old cars, you may find a wire that shows 12-volts with the key on, but when you turn the engine over, the voltage drops considerably which will lead to any number of issues with the ECU. Search for a separate, stable 12-volt terminal for your keyed on/off connection.
SENSORS
An EFI system depends on the constant input and feedback of several sensors including coolant temperature (CTS), manifold pressure (MAP), throttle position (TPS) and of course, an oxygen sensor (O2) that is placed in the exhaust. Some throttle body systems have a built in MAP and TPS, but the two sensors you can always count on installing are the coolant temp and the O2 sensor.
In regards to the O2 sensor, it requires being installed in the exhaust pipe or header collector and in most cases will require a bung to be welded in place. The wide band oxygen sensor of the EFI system constantly monitors the oxygen content in the exhaust which is relayed to the ECU so it can adjust the fuel delivery to maintain the proper air/fuel ratio. If there are any leaks in the exhaust system, it will skew the O2 sensor’s values and give the ECU false information resulting in the wrong air/fuel mixture and poor driveability.
As for the coolant temp sensor, it shouldn’t be difficult to find a port on the heads or intake manifold but it depends on engine. If your engine only has one port which is used for the dash indicator or gauge, you’ll have to figure out an alternative. Also, if you’re running an external MAP sensor, be sure it is connected to a manifold vacuum source – not a ported source!
Fuel System
Probably the most time consuming aspect of an EFI swap is upgrading the fuel system. Every EFI system requires higher fuel pressure in the realm of 40-60 psi and your old mechanical pump is not going to cut it. An electric fuel pump, generally one recommended by the EFI company, will need to be installed – and the proper place for that pump is in the fuel tank.
Yes, in some cases the pump can be mounted inline near the tank, but for quiet operation and longevity, do yourself a favor and put the pump in the tank. There are several reasons for this: Pumps are made to push fuel, not pull it. The pump stays cooler thanks to the fuel engulfing it. And, the pump is a lot quieter when mounted internally.
There are several ways to accomplish mounting the pump in the tank. First and foremost is to simply invest in a new tank that is prepared for EFI. Tanks Inc, Holley, and FiTech all offer new tanks with a sending unit designed to secure the pump and have the fittings for a feed and return line. There are also kits available that can help you modify your stock tank to accept a pump module with a bit of time cutting and drilling.
When it comes time to provide voltage to that fuel pump back in the trunk, many applications will call for a relay to be used to handle the higher demands of the pump. Make sure to run a quality wire of the recommended gauge to the pump – and be sure to connect to a good ground source. And for the record, the truck floor pan is not considered a good ground.
To support this newfound fuel pressure, it is important to run high pressure fuel hose from the tank to the fuel rails or throttle body. In most cases you’ll be running two lines; one as a feed line and one return line back to the tank. It is important to use the recommended high pressure hose or braided lines with the corresponding fittings and clamps. Fuel lines are not a place to scrimp or cut corners!
When plumbing the system, be careful about using any existing hardlines on your vehicle as they may not be able to supply to volume of fuel your system requires. Also, plan to keep the return line the same diameter as the feed line allowing for consistent flow.
One last fuel system consideration is the need for a regulator to set the required fuel pressure accurately. Some systems have a built-in regulator but if required, you need to plan your fuel line routing and be sure to have the right fittings to finish the job.
If you learned anything from this overview and tips from the pros, it’s that EFI requires the support of your vehicle’s entire electrical system as well as new fuel delivery system. By doing a little research to select the right parts for your application and in taking the time to install and connect everything properly, you’ll reap the benefits of EFI for miles to come.
Tips from the Pros
Healthy Engine and Ignition – Happy EFI
“It’s common that customers install an EFI system without considering the condition of their engine. Our systems upgrade the fuel delivery to your engine, but it is important that your engine is in good condition to perform. An engine that is doesn’t run efficiently or has issues with a carb, it going to have the same issues with fuel injection. Upgrading to EFI will bring many benefits to your engine, but it’s important your engine is performing well as well.
“Before you upgrade to EFI, make sure the engine is in good shape with no compression issues and a little general maintenance such as checking for vacuum leaks, the valve train, changing oil and filters, replacing the spark plug and wires can make a big difference. Speaking of the ignition system, upgrading to a stronger ignition for an improved spark can improve your EFI experience. Fuel and sparks go together when it comes to performance.” – FiTech EFI
One System – No Mismatches
Howell “When you start getting into engines from engines built in 1999 and newer, mismatching different parts can cause many issues as these engines just get more complex in later years. It’s best, whenever possible, to retain the transmission and as many ancillary components there were original to the engine and application when you’re pulling it from a donor vehicle.
“If you’re going to retain the Drive by Wire system of an LS, be sure save the throttle body and the TAC module from the vehicle. You’ll also have to know if your engine has a 24x or 58x cam sensor. If you’re retaining the stock ECU, you’ll need to have it reprogrammed and not only will you need to know the details about your engine and find a respected company that understands the complexity of your system. Not understanding your engine’s original application, as well as any changes you made with a new cam or induction, will cause delays and frustration.” – Howell EFI
Battery Connections
“One of the most common issues of supplying power to the ECU of your fuel injection system is when customers don’t go right to the battery posts. Even if it means the wires must be extended to reach the battery in the rear of the vehicle, make sure to connect the main power wires right to the battery’s clean terminal posts! Do not connect the main power wires to junction blocks, bus bars, fuse panels, ground lugs, etc – go right to the battery terminals for a solid, clean connection – but make sure there’s not six other devices connected at the same terminal. A little bit of extra work with your wiring during initial installation can save hours of trying to troubleshoot problems later.” – Edelbrock
Upgrade the Vehicle Electrical System
“Not having an adequate vehicle electrical system is a common issue. An EFI system in itself is a complex electrical system and if vehicle has an old antiquated electrical system, the EFI system will never work properly.
“Be sure to have a proper charging and starting system. You are typically adding more electrical devises to the car and the original charging system may not keep up with the added demands of computers, ignition systems, fuel pumps, etc… Also, do not shortcut battery power and grounds. When relocating a battery to the back of the car it is critical to run the ground cable all the way to the battery. Remember, when the battery was in the front, it grounded directly to the engine. It should still do that when relocating it to the back.” – Autotrend EFI
Leak-Free Exhaust
“Any self-learning EFI system relies heavily on good readings from the oxygen sensor. Too many times we’ve seen loose header bolts, poor bung welds, and other leak sources that cause erroneous O2 readings. This leads to the ECU trying to adjust the fuel mixture to achieve the set target air/fuel ratio and is the number one cause of poor performance.
“Make sure your exhaust system is completely sealed from cylinder head to tailpipe, upstream and downstream of the O2 sensor. Locking hardware to secure the exhaust is recommended, and fasteners should be retorqued as part of routine maintenance. Also, if any RTV Silicone is used to seal the exhaust, make sure it is compatible with Oxygen Sensors.” – FAST Fuel Injection
Fuel Pressure and Instructions
“Proper fuel pressure is critical for EFI so when a customer calls about having issues with the fuel system, we go over the entire installation and ask if they verified fuel pressure. Many times the fuel pressure is not correct, and we suggest they get a fuel pressure gauge and perhaps an adjustable fuel pressure regulator to fix the issue.
“You need to understand and follow the instructions that come with the EFI system. While many systems have some bolt-on aspects, there are tuning, fuel system, and other aspects that require following the manufacturer’s specific instructions to the letter. EFI is not just a fancy electronic carburetor that can be bolted on quickly and activated with the turn of a key. Read the instructions before starting the installation.” – Summit Racing
