An Iridium Fine-Wire Center Electrode in a Box of Four Plugs
NGK part number 4772 is a box of four Iridium IX spark plugs, factory-coded DR9EIX. NGK builds the Iridium IX line around a fine-wire iridium center electrode, which the manufacturer’s own product description states is roughly six times harder than platinum, paired with a tapered-cut ground electrode for improved starting, idling and throttle response.
Key Features
- Iridium fine-wire center electrode, roughly six times harder than platinum per NGK
- Tapered-cut ground electrode for improved starting, idling and throttle response
- High melting point iridium alloy suited to sustained high combustion-chamber temperatures
- Sold as a box of four, factory-coded DR9EIX
Fitment
| Years | Make | Model | Notes |
|---|---|---|---|
| n.a. | n.a. | n.a. | Verify physical dimensions against the application before ordering. |
Specifications
| Detail | Value |
|---|---|
| Brand | NGK |
| Line | Iridium IX |
| Factory code | DR9EIX |
| Quantity per box | 4 |
| Center electrode material | Iridium, fine-wire |
| Ground electrode | Tapered-cut |
What’s Included
- One box of four NGK Iridium IX spark plugs, factory-coded DR9EIX.
About NGK
NGK builds this product around the specifications described above; verified details are sourced from the manufacturer-provided product description supplied with this listing.
FAQ
What does the DR9EIX factory code identify?
NGK’s own factory code for this Iridium IX spark plug; use it to cross-reference against the engine’s specified heat range and thread size before ordering.
How many plugs come in this listing?
Four, sold together as one box.
What is different about the Iridium IX’s center electrode?
NGK describes a fine-wire iridium center electrode with a melting point and hardness NGK states is roughly six times that of platinum.
What does the tapered-cut ground electrode do?
NGK states it improves starting, idling and throttle response compared with a standard ground electrode.
Is vehicle-specific fitment published with this listing?
No. Verify the DR9EIX heat range and thread specification against the engine’s original-equipment plug.
Can these be used as a direct swap for a lower NGK line?
Confirm the exact heat range and reach against the factory-specified plug; NGK’s own text does not state that Iridium IX is a drop-in for every other NGK line in every application.
What upgrade path does NGK suggest from this line?
NGK’s own description suggests the Ruthenium HX line for even greater performance.
Are these gapped from the factory or is gapping required?
Check the plug gap against the engine manufacturer’s specification before installation.
Installation Instructions
NGK’s own product description covers plug design and material rather than a step-by-step installation or torque procedure. Use the vehicle’s factory service information for torque values and removal sequence.
- Confirm the DR9EIX factory code matches the plug specified for the engine before removing the old plugs.
- Allow the engine to cool completely before removing spark plugs.
- Remove the ignition coil or plug wire, then use a spark plug socket to remove the old plug.
- Inspect the new plug’s gap against the vehicle manufacturer’s specification before installation; NGK does not publish a universal gap for this listing.
- Thread the new plug in by hand until it seats, then torque to the vehicle manufacturer’s specification using a torque wrench.
- Reinstall the ignition coil or plug wire and repeat for the remaining plugs.
- Start the engine and confirm smooth idle before returning the vehicle to service.
