What the 5.7 Hemi firing order is and why it matters

The firing order of a 5.7 Hemi engine is 1-8-4-3-6-5-7-2. This is the sequence in which the eight cylinders ignite, one after another, to create the power strokes that turn the crankshaft. The Hemi (short for hemispherical) refers to the shape of the combustion chamber, not the firing pattern itself — but knowing this specific order matters if you are rebuilding the engine, replacing spark plugs, or diagnosing a misfire.

The cylinders are numbered from front to back on each side of the engine. On the driver's side, you have cylinders 1, 3, 5, and 7. On the passenger's side, you have cylinders 2, 4, 6, and 8. The firing order alternates between sides to keep the engine balanced and running smoothly. If the spark plugs fire in the wrong order, the engine will run rough, lose power, or not start at all.

Key Takeaways

  • The 5.7 Hemi fires its cylinders in the order 1-8-4-3-6-5-7-2, alternating between the driver's and passenger's sides of the engine.
  • Cylinders 1, 3, 5, and 7 are on the driver's side; cylinders 2, 4, 6, and 8 are on the passenger's side, numbered front to back.
  • Connecting spark plug wires or coils in the wrong order will cause misfires, rough idle, and loss of power.
  • The firing order stays the same across all 5.7 Hemi engines, whether in a Dodge truck, Jeep, or Chrysler vehicle.

How cylinder numbering works on the 5.7 Hemi

The 5.7 Hemi is a V8 engine, meaning the cylinders are arranged in two rows of four, one row on each side of the engine block. Standing in front of the engine and looking back, the driver's side (left) holds cylinders 1, 3, 5, and 7 in order from front to back. The passenger's side (right) holds cylinders 2, 4, 6, and 8, also front to back.

This layout is standard across all Chrysler V8 engines. The front of the engine is where the serpentine belt and water pump sit. The back is where the transmission bolts on. When you are working on the engine, always confirm which side is which by facing the front of the vehicle — this prevents confusion when you are routing spark plug wires or removing components.

Reading a spark plug wire diagram for the 5.7 Hemi

If you are replacing spark plugs or spark plug wires on a 5.7 Hemi, you need to know which wire goes to which cylinder. The distributor cap (on older models) or the coil pack (on newer models) has eight terminals, one for each cylinder. The firing order tells you which terminal connects to which cylinder in sequence.

On models with a distributor, the rotor spins and touches each terminal in firing order: 1, then 8, then 4, then 3, then 6, then 5, then 7, then 2, and back to 1. The spark plug wires attach to the cap in a circle, and you must route them so that the wire from terminal 1 goes to cylinder 1's spark plug, the wire from terminal 8 goes to cylinder 8's spark plug, and so on. On newer 5.7 Hemis with individual coil packs mounted directly on the spark plugs, each coil is labeled with its cylinder number — straightforward match the label to the cylinder.

The most common mistake is installing wires in numerical order (1-2-3-4-5-6-7-8) around the cap, which is wrong. The firing order is not numerical. Take a photo of the original wire routing before you remove anything, or write down which wire came from which terminal before you disconnect them.

What happens if the firing order is wrong

If spark plug wires are installed out of order, the engine will not run correctly. The most obvious sign is a rough idle — the engine shakes or vibrates even when parked and in neutral. You may also hear popping or backfiring through the exhaust or intake, especially when accelerating.

A misfire occurs when a cylinder does not fire at the right time. The unburned fuel-air mixture exits the cylinder and ignites in the exhaust system, creating the popping sound. Over time, this can damage the catalytic converter and oxygen sensors. The check engine light will come on, and a diagnostic scan will show misfire codes for one or more cylinders.

In severe cases, the engine may not start at all, or it may start and when ready stall. If you have just replaced spark plugs or wires and the engine suddenly runs badly, the first thing to check is whether the wires are in the correct order. Swapping two wires back to their original positions often fixes the problem when ready.

Differences between older and newer 5.7 Hemi engines

The 5.7 Hemi has been produced since 2003, and the firing order has remained the same across all model years: 1-8-4-3-6-5-7-2. However, the ignition system has changed. Older models (2003 to roughly 2008) use a distributor and spark plug wires. Newer models (2009 and later) use individual coil packs that sit directly on top of each spark plug, eliminating the need for wires.

If you own an older 5.7 Hemi with wires, you must route them correctly around the distributor cap. If you own a newer model with coil packs, the firing order is less likely to be a problem you encounter, because each coil is already labeled and bolted to its cylinder. However, if you are rebuilding the engine or replacing the valve cover gaskets, you still need to know the firing order to may support you install components in the correct sequence.

Steps to verify the firing order on your engine

If you are unsure whether your spark plug wires are in the correct order, you can verify the firing order by checking the engine block or the owner's manual. Most 5.7 Hemis have the firing order stamped or cast into the intake manifold or valve cover. Look for a series of numbers, usually small and raised or recessed into the metal.

Another way to confirm is to locate cylinder number 1. On the 5.7 Hemi, cylinder 1 is the front cylinder on the driver's side. Once you have identified cylinder 1, you can count forward to find the other cylinders. Then, trace the spark plug wire from cylinder 1 back to the distributor cap terminal it came from. That terminal is position 1 on the cap. From there, you can follow the firing order around the cap to verify that each wire is in the correct position.

If you are working with a newer model that has coil packs, straightforward remove one coil pack and look at the cylinder number stamped or printed on it. The coil packs are usually arranged in two rows on top of the engine, and each one is clearly marked.

Frequently Asked Questions

Is the 5.7 Hemi firing order the same in a Dodge truck and a Jeep?

Yes. The 5.7 Hemi engine is used across multiple Chrysler brands — Dodge, Jeep, Ram, and Chrysler — and the firing order is always 1-8-4-3-6-5-7-2, regardless of the vehicle. The engine itself is identical; only the mounting and accessories change.

Can I look up the firing order on the engine itself?

Yes. Most 5.7 Hemis have the firing order cast or stamped into the intake manifold, valve cover, or engine block. It is usually a small series of numbers. If you cannot find it on the engine, check your owner's manual or the service manual for your specific model year and vehicle.

What if I accidentally swapped two spark plug wires?

The engine will misfire on those two cylinders. You will notice a rough idle, loss of power, and possibly a check engine light. Swap the wires back to their correct positions, and the problem should go away when ready. If the misfire persists after you have corrected the wires, have the spark plugs and ignition coils checked.

Do I need to know the firing order to change spark plugs?

Not necessarily. If you are only changing the spark plugs and not touching the wires or coil packs, you can remove and replace one spark plug at a time without worrying about the firing order. However, if you are removing all the wires or coil packs at once, knowing the firing order helps you reinstall them correctly.

Does the firing order change if I modify the engine?

No. The firing order is determined by the crankshaft and camshaft design and does not change with modifications like a cam swap, intake manifold change, or exhaust upgrade. The cylinders will always fire in the order 1-8-4-3-6-5-7-2.