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MSD Atomic EFI Install Manual
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Part Number: 2900

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MSD has been known for decades as the premier performance ignition company. Its capacitive discharge multiple spark technology helps to make your car or truck perform better, idle smoother, burn cleaner, and improve mileage. Now, MSD has once again revolutionized performance with the Atomic EFI fuel system. Atomic EFI is the most complete, turn-key, easy to use, fuel injection conversion system. It is simple to install and setup without a laptop or tuning knowledge. There truly has never been any standalone EFI system as effective, visually appealing, and economical as the MSD Atomic EFI. So, what are you waiting for? Stop struggling with that dirty carburetor and go Atomic with MSD's Atomic EFI.

Key features that set the Atomic EFI apart from the rest:

  • Self-Mapping Fuel Settings: The Atomic EFI includes a Wide Band Oxygen Sensor (similar to ones used at dyno shops). This sensor will allow the Atomic ECU to tune itself constantly while you drive. What about if I change headers or cylinder heads? Or what happens if I change the cam (handles duration up to 250 degrees @.050)? No Problem. The Atomic will adjust the fuel settings accordingly.
  • Advanced Ignition Timing Control and Special Integration with MSD Ignition Systems and Distributors
  • Rev-Limit Control
  • Idle Control
  • Electric Fan Control
  • A/C Kick-Up feature
  • Cold Start Feature
  • As little as 8 Simple Clean Wire Connections
  • Clean and Compact Aluminum Throttle Body Assembly: The Atomic throttle body assembly is designed to resemble a carburetor. It bolts onto common 4150 and 4160 square bore 4-barrel intake manifolds and accepts your stock air cleaner. The aluminum housing was designed to house the wiring, ECU, fuel rails, fuel injectors, sensors, and throttle blades. The Atomic throttle body is also designed to accept your throttle linkages for seamless installation. MSD went the extra mile to make the Atomic EFI - Clean, Effective, Easy to Use.
    • Internal Fuel Rail: MSD designed the fuel rail to be integral to the throttle body assembly. Not only does this create a sleek appearance, it removes fitting connections where leaks could develop. Also not that with a single fuel line, you can bring the fuel line up from the back or use the front fitting.
    • Annular Rings: Notice the annular rings atop the Atomic? These were incorporated to deliver superior fuel atomization of the mixture resulting the best air/fuel mixture possible. This design ensure the best possible air/fuel mixture delivery to each cylinder. This improves idle quality, reduces cold start time, and increases fuel economy and power.
    • Mount and Blades: The Atomic throttle body bolts right in place of a standard square bore carburetor and accepts the same linkage as most setups. The throttle inlets are 1.75" diameter and ride in precision roller bearings for smooth pedal transition.
    • Internal ECU and Senors: Yes, the ECU is integral to the throttle body! It is not remote mounted like other brands. This unique design reduces wiring and keeps your EFI installation easier than ever. Better yet is that MSD incorporated into the Atomic the TPS (Throttle Position Sensor), MAP (Manifold/Barometric Pressure Sensor), IAT (Inlet Air Temperature), and Fuel Pressure sensors into the ECU. In fact, the only sensors you need to install and connect are the provided coolant temperature and wide band oxygen sensor.
    • Internal Injectors: Fuel delivery is provided by four precision 80 lbs/hr. injectors rated at 60psi. These injectors feature a stainless steel ball and seat metering method for maximum internal sealing. For secure mount the injectors are sealed between the housing and the integral cast fuel rails.
    • Unique Throttle Position Sensor: The Atomic's TPS is unlike any you have used before. It is an automatic, self-calibrating, non-contact sensor. That means you don't have to worry about configuring it during set up or re-calibrating it after doing engine work. You also don't need to worry about having to replace it when the contacts (this is a non-contact sensor) wear out like in other competing systems.
    • Hi-Flow: Flows over 1000cfm which is plenty and enough for engines making over 600HP. The injectors can supply the fuel requirements for up to 620HP rated at the crank with the optional high horsepower fuel supply kit (sold separately).
  • Simple and Sleek Power Module: Continuing MSD's dedication to make Atomic the most "Clean, Effectice, and Easy to Use system", engineers used the latest technology in vehicle communications to design the power module. While the rectangular red ribbed power module can be easily mistaken for the ECU (remember the Atomic ECU is actually built into the throttle body assembly), it really acts as your replacement for the complicated and unsightly "wiring mess" associated with routing wiring to and from the components and acts as the relay box between your fuel pump, handheld, heated wide band oxygen sensor, and existing vehicle electrical system. It handles all the high current loads. MSD utilizes modern CAN-Bus technology which allows for a single, clean connection between this unit and the throttle body mounted ECU.
    • CAN-Bus: The two ports on the bottom of the Atomic power module are for MSD's CAN-Bus technology. Just plug in the pre-made throttle body harness and the pre-made harness for the handheld controller and you are ready to go - nothing complicated or unsightly! Best of all, these two ports are interchangeable, so don't worry about which plug goes where.
    • Wiring: Most of the wiring for the Atomic EFI comes through this loom. This includes the fuel pump power (No relay required!), two electric fan controls, Wide Band Oxygen Sensor, 12 volt switched power, and ground.
    • Mounting: The power module for Atomic can be mounted almost anywhere you like. If you want to show off the neat red exterior on the firewall or fender under the hood you can. Or if you want to keep it tucked out of sight, just keep it somewhere away from much water and with some air flow.
  • Handheld: This little device is how you communicate with the Atomic. That's right, no laptop or special software required! The initial setup takes about 5 minutes to answer a few basic "car guy" questions about your engine. After that, the handheld serves as a dash for you to see all that is happening with your engine!
    • Easy to Use: MSD knows the handheld must be easy to use and without a laptop or expensive software. This wasn't made for a rocket scientist or a software engineer or a dyno-tuner only setup. The handheld is in plain English for the car enthusiast that will use it. In the Initial Setup, you will answer six (yes just six) basic questions about your engine like Cubic Inches, Number of Cylinders, Cam Type, desired rev limit, type of fuel pump setup, and idle setting. There are additional parameters to modify under the Advanced menu that are included but not necessary to use for most applications. The advanced parameter features include ignition timing control, target air/fuel ratios, a/c kick-up, electric fan control, pump squirt, power valve enrichment, and nitrous control. Again, the advanced features are not necessary for most vehicles to get up and running but are included to support the wants or needs of advanced users and enthusiasts.
    • Dash Functions: After the initial setup is complete, you may think that the handheld is useless; not so! The handheld functions as a dash board that can serve you any time you want to know what's happening in the engine. This includes A/F ratio readout, coolant temp, rpm, spark timing, etc. This setup tells you everything you want to know about your engine.
    • Data and Diagnostics: The data Atomic gathers doesn't just disappear after you look at it on the dash. If ever an issue arises, the diagnostics feature will display alerts and trouble codes, and save them for up to ten starts to let you come back and see what is going on.
  • Complete Fuel System: Unlike other companies that make you search for fittings, hose, and fuel system components to use their standalone fuel injection system, MSD again worked to make your installation Clean, Effective, and Easy To Use. The Atomic fuel kit includes everything you need to get you up and running including a PWM (pulse width modulated) fuel pump, 15 feet of 3/8 inch EFI fuel hose, mounting brackets, fuel filter, and EFI hardware and fittings for a proper fuel system installation. The PWM fuel pump is similar to modern fuel pumps found in today's vehicles. It allows the computer to increase or decrease the output of the fuel pump as needed so no return line to the fuel tank is needed. Also, the fuel pump can be converted to a return-style system easily with the push of a button within the handheld. This fuel system is designed to support normally aspirated engines producing up to 525HP at the crank. The fuel pump can be upgraded in MSD's High Horsepower fuel kit for engines making over 525HP up to 620HP at the crank.

MSD Atomic EFI Before and After Test
Atomic EFI TB Installation Video
MSD Factory Tour

Return Style Fuel System Setup: The setup for a return style fuel system configuration is very important. The common setup will not work on the Atomic EFI. Please see Diagram below:

Camshaft Selection: There are three selections; Street/Stock, Mild and Performance. Select the cam that best suits your application.

Note: If lobe separation angle (LSA) is less than 108 you may need to go to the next larger cam profile. If cam duration is longer than 250 the Atomic EFI will not be suitable for your application.

What is the operating fuel pressure?
30-75PSI if you are using a PWM system (Pulse Width Modulated Returnless system). If you have your own, regulated system required pressure will depend on horsepower. Most vehicles will use close to 45psi while cars pushing 600HP will need closer to 70psi.

If I already have a fuel system what pressure do I set?
Dependent on horsepower, most cars will require 45psi unless you are putting out very high horsepower. There is a DTC (diagnostic trouble code) that indicates 100% injector duty cycle. If this condition is hit, you will need to increase your fuel pressure by a slight amount (5-10psi) and try again. Please see instruction page 6 for more information.

What size injectors?

They are 80lb/hr @ 60PSI.

What fuels can I run?
The Atomic has been designed and calibrated to run on gasoline with up to 15% Ethonal added. It is safe to run E-85, but the calibrations will be wrong. All fuel tables, including start-up, normal run, and transients will have issues with E85 fuel. Only attempt to run E-85 if you are familiar with the common corrections for these issues.

Can I run boost or Nitrous with the system?

How much current will the fuel pump and fan drivers support?
The fan drivers only support 1-2 amps meaning they will only drive the low current side of a relay. The fuel pump output can support 20 amps continually without the need for a relay.

Can a 16-24 volt system be used?
The Atomic is designed to run on 12 16 volts. Voltage should not exceed 16 volts, meaning a 16 volt system with an alternator is not supported.

What RPM inputs are accepted?
A magnetic, points or standard coil negative will work, but not a hall-effect 5V signal. The signal out of any MSD distributor or MSD Ignition Control Unit will suffice to supply an RPM signal for the Atomic. NOTE: An Ignition Control Unit is required with most applications.

What sensors are onboard and can I replace them?
There is a 2-bar MAP (Manifold Absolute Pressure) sensor, Fuel Pressure sensor, Inlet Air Temperature sensor, Throttle Position sensor and Idle Air Controller (IAC). The Throttle Position sensor is a proprietary non-contact sensor that should not need to be replaced. The Fuel Pressure, MAP, and IAC may be replaced by sending the units in to MSD if necessary.

Whats the CFM of the throttle body?
The Atomic EFI throttle body can flow approximately 1000 CFM. The horsepower is not limited by airflow rather it is limited by injector size.

What exactly does the A/C RPM step up do and is it adjustable?
The computer tells the IAC to open when it sees a 12V signal on the A/C input line so it can open before the load is actually put on the engine, preventing the RPM from dropping. It does not actually raise the base idle RPM. It is factory pre-set and is non-adjustable.

Where do I set base timing when using the unit to control timing?
Under the "Initial Setup" screen on the Atomic EFI handheld, you will select "ENABLED" for Timing Control. Next, under "Advanced Setup", find parameters to set a timing curve. The Atomic is limited to 44 degrees of total timing (including vacuum advance) due to the limits of a distributor. For complete details and instructions on this, please see Page 15 of the instructions.

Can I plot a custom timing curve, and can I lock the timing out in the software?
Yes, you can set any base idle timing (minimum 500RPM) you would like, along with any total timing (minimum 1500RPM) you would like. In addition to this, you would be able to set a start RPM where the idle timing starts to advance towards total timing. You will also set the RPM at which timing reaches total timing. This will act like one of our distributor spring/bushing kits, but is not limited and can be set exactly. You cannot do a custom 3D timing table. No the timing curve cannot be locked out. The base timing can be set as early as 500 RPM and the fastest advance curve will end at 1500RPM.

Is there a start retard?
There is no start retard setting. However, if the Atomic is controlling ignition timing the Idle Timing setting entered in the system will be used during starting. If idle timing is set to 10 degrees that is what timing will be during cranking. For example, if the engine needs a lower timing for cranking, you can set your idle timing lower (i.e. 5 degrees). By beginning the timing ramp at 500 rpm with Total Timing at 35 degrees at 2000 rpm. This will create a retarded start with 2 degrees of advance 100 rpm through 2000. At an 800 rpm idle, ignition timing will be 11 degrees. This is one example of the many options available; always find the settings that will work best for the particular engine.

Is there vacuum advance?
There is a selectable vacuum advance from 0-15 degrees. It maxes out below 16 Hg manifold vacuum and is completely gone by 7 Hg manifold vacuum so it acts like a normal vacuum pot, only the total amount of vacuum advance is user adjustable, where as the rate of advance is non-adjustable. By setting the vacuum advance to 0, the vacuum advance is disabled.

What other timing capabilities does the system have?
The Atomic EFI has idle timing control since it is much faster than an IAC. The IAC is slow in responding to RPM changes compared to controlling idle speed through variations in timing to help maintain the idle RPM target. If you notice the idle timing jumping around, do not be alarmed, it is a normal function and will go away as soon as you touch the throttle.

Whats the smallest and largest CID that can be selected?
The Atomic EFI will support engines with as at least 100ci to 800ci (maximum).

Can injector size or fuel pressure be adjusted to accommodate larger or Small CID, or increased HP?
Injector size cannot be changed. If you are using your own system with a regulator, fuel pressure can be changed. A low horsepower engine would benefit from using a fuel pressure regulator and setting the fuel pressure lower. We have successfully tested a 305cid engine with 200 horsepower using the PWM system and the air fuel ratio was fine at 500 RPM.

What can be selected or adjusted via the hand held controller?
There are only a few things that must be changed between combinations.
Basic setup: Engine displacement, number of cylinders, fuel pump type (return or PWM), idle RPM, Rev-limit, timing control, three camshaft type selections (street, mild, performance)
Advanced setup: Fans (separate on temp for both fans), AFR targets (idle, part throttle, wide open), Ignition timing (curve settings), Pump squirt (0-100%)

Will the unit compensate for altitude and does the key need to be cycled to do so?
On altitude changes, the unit will compensate for altitude changes if you go above 50% throttle and are between 1200 and 3000 RPM. You can also cycle the key to the off position for 3 seconds which will have the same effect.

What type of Rev-limiter does the Atomic EFI use?
The Atomic uses a fuel cut-off rev limiter.

Does the unit increase idle speed and fuel for cold starting and warm up?
Yes. Cold start conditions will be automatically compensated for and will decay out as the engine warms up. By the time it reaches 145F, idle speed and fuel compensation are completely removed.

Will it hurt the unit to keep the key in the on position with 0 rpm for an extended period of time?
No, it will not hurt the unit. However, the WBO2 sensor will be drawing current the entire time for its heating plug. (NOTE: The O2 sensor will be hot if the key is left in the on position. Care should be taken to avoid burns).

How many pulses per crankshaft revolution are needed for the RPM input?
The Atomic must receive one pulse per combustion (4ppr on a V8).

How much current is the total system capable of drawing?
If both fans are on, the fuel pump is at full capacity the IAC is moving, and the injectors are at their maximum and the input voltage is around 10V it can draw as much as 30amps. Normal operation will be approximately 14-18 amps.

Will the system work on a 6 volt system?

Can the unit drive the coil directly?
No, the Atomic EFI doesnt have a built in ignition driver and must be used in conjunction with an ignition box or a Ready-to-Run style distributor. Points and HEI distributors also need an ignition box to operate the Atomic.

Do the annular rings work the same as a carburetor?
No. The annular rings on the Atomic throttle body are designed by MSDs engineers to work as special injector nozzles. The rings are not in a venturi and at no time does the fuel get pulled out because of low pressure. They help to spread the fuel out and have been shown to improve per cylinder fuel distribution. Even cylinder distribution, like that from a carburetor, helps make more consistent high rpm horsepower.

What are the HP capabilities of the system and what are the limiting factors?
With a large pump the maximum output of the Atomic is 625 HP. The limiting factor is the injector size. The Atomic EFI utilizes four 80lb/hr injectors.

How far can the pump be mounted from the tank?
The Atomics fuel pump should always be mounted as close to the fuel tank as possible. Using a return style system this is less vital, but a closer mount will aid in keeping the pump cool. Using a returnless style fuel system it is vital that the pump be as close as possible. With this system the pump MUST be within four feet of the tank preferably two feet or less. The pump should always be at or below the bottom of the tank. The pump should be plumbed with the supplied 3/8 ID fuel line from the tank.

Is the pump supplied with the Atomic EFI Master Kit a puller / pusher or just a pusher style fuel pump?
The fuel pump is a pusher pump only which is what creates the limits on mounting options.

Is there a limitation to how long the CAN extensions can be?
The can extensions cannot exceed six feet in total length.

Is the unit susceptible to RF noise from other electronics and or the ignition system components?
The Atomic EFI utilizes shielded CAN and magnetic pick wires which help cut down on noise interference. Still, the wiring from the Atomic EFI should not be routed in close proximity of the spark plug wires.

What are the temperature limitations (hot and cold) for the system?
The Atomic EFI can withstand under hood temperatures in excess of 200*F and as low as 0*F.

Are the TBI, Power Module, and components water resistant or water proof in wet/ humid environments (or when washing the motor)?
The units are potted and are resistant to water intrusion although should not be immersed. Normal motor washing should be fine but never point a high pressure water source directly at electrical items.

Where is the unit made?
All research, design, programming, assembly, and final testing are done by our skilled technicians in El Paso, Texas.

Can it run an LS motor?
Yes, with the addition of a MSD PN 6010 box, it can handle the fuel delivery, but not individual coil spark.
If you are running a front mount distributor and single coil, you will be able to use timing control with an ignition box.

Does it require a phaseable rotor if I run timing control?
Yes. If you are running ignition timing control through the Atomic a number of other small items are required. Please see Page 15 for a list of required items.

Does the unit have a ported vacuum outlet?
Yes, there is a ported vacuum outlet on the throttle body. Customers can still use a stock distributor vacuum advance if desired.

What happens if the WBO2 sensor fails?
The handheld will display a DTC (Diagnostic Trouble Code) for the sensor. The engine will be allowed to continue running, but will use only the existing fuel tables. Fuel table adjustments or self-tuning will be deactivated.

Does a target AFR (Air Fuel Ratio) need to be set before start up or is there a base target AFR?
The Atomic comes with default Air Fuel Ratios that should be sufficient for most street based engines. However, if a change in AFR is desired the settings can be found in the Advanced Setup on the Handheld controller.

What is AFR (Air Fuel Ratio)?
An Air Fuel Ratio is the volume of air per each unit of fuel put into the engine. 14.7 units of air per 1 unit of fuel is stoichiometric meaning there is the exact right amount of air available to burn all of the present fuel. A lower AFR number means there is less air to match the fuel, and therefore the engine will run Richer. Oppositely, a higher AFR number means that there is more air to match the fuel and the engine will run Leaner.

Air Fuel Ratio scale-

For more information click on the link below-

Can I install larger injectors?
No. The Atomic EFI will not accommodate different sized injectors.

Can it be set up as a dual quad?
No not at this time. There are a number of changes that will need to take place before this is an option.

If I use a bigger pump, will it work up to 800?
No, the injector duty cycle will still max out.

Is the Atomic EFI UL approved for marine use?
No. The Atomic EFI is not UL approved at this time.

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