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Denso 4033 Spark Plug
| Brand | Denso 4033 |
|---|---|
| Center Electrode Core Material | Copper |
| Center Electrode Tip Material | Nickel |
| Ground Configuration | Standard |
| Ground Electrode Core Material | Nickel |
| Ground Electrode Quantity | 1 |
| Ground Electrode Tip Design | U-Groove |
| Hex Size | 20.6 |
| Manufacturer Heat Range | 24 |
| Pre-Gap Size | 0.8 |
| Reach | 19.00 |
| Resistance | 5000 |
| Seat Type | Flat |
| Thread Diameter | 14.00 |
| Product line | U-Groove Conventional |
| Fits | Polaris, Ski-Doo, Yamaha, Kawasaki, KTM, Gas Gas, Sea-Doo, Honda, Aprilia, Wet Jet, Arctic Cat, Porsche, John Deere, and Renault · 18 vehicles |
U-Groove design. Improves ignitability for more efficient engine operation.
Copper core. Helps promote consistent spark performance.
Nickel electrodes. Built with nickel tip and ground materials for dependable firing.
Cross-references DENSO Auto Parts W24ESR-U and Porsche 999 170 128 90 for the same application. See all 2.
Denso 4033 Spark Plug for Porsche 911
The Denso 4033 is a conventional spark plug built for Porsche 911 applications across multiple model years. Its U-groove ground electrode design is engineered to improve ignitability, helping support more efficient combustion in the engine.
Key Features
- U-groove ground electrode tip design for improved spark exposure
- 5000 ohm resistor for ignition noise suppression
- Copper center electrode core for stable heat transfer
- Nickel center and ground electrode tip materials
- Standard ground configuration with a flat seat
- 14.00 mm thread diameter, 19.00 mm reach, and 20.6 mm hex size
- Pre-gapped to 0.8 mm
Product Details
Built under Denso’s U-Groove Conventional line, this spark plug focuses on dependable secondary ignition performance with a design that helps the spark kernel form more easily at the plug gap. The copper core and nickel electrode materials support consistent operation in classic Porsche 911 engines, while the resistor design helps reduce electrical interference in the ignition system. This part number is 4033, and it cross-references DENSO Auto Parts W24ESR-U for the same application.
Common Uses
- Restoring weak or inconsistent spark in Porsche 911 ignition systems
- Addressing rough idle caused by worn spark plugs
- Helping correct hard starting in older Porsche 911 engines
- Reducing misfire symptoms tied to aged secondary ignition components
- Replacing plugs with excessive electrode wear or gap growth
Installation Notes
Compatible With 1965-1967 Porsche 911, N/A; 1969-1971 Porsche 911, N/A; 1974-1977 Porsche 911, N/A; and 1984-1989 Porsche 911, N/A. Verify thread diameter, reach, seat type, and pre-gap before installation. Use the specified torque procedure for the cylinder head and confirm ignition wire condition, coil output, and plug wire routing during service. The part number 4033 should be matched to the vehicle’s required heat range and ignition specification before final assembly.
Quality Assurance
Denso is a recognized OE supplier in ignition components, and the U-Groove Conventional design is built to meet the demands of classic Porsche 911 service. Confirm fitment against the vehicle’s engine specification and service data before installation.
| Year | Make | Model | Submodel | Position | Notes |
|---|---|---|---|---|---|
| 1989 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1988 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1987 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1986 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1985 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1984 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1977 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1976 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1975 | Porsche | 911 | Carrera | N/A | U-Groove Conventional |
| 1974 | Porsche | 911 | Carrera | N/A | U-Groove Conventional |
| 1971 | Porsche | 911 | S | N/A | U-Groove Conventional |
| 1971 | Porsche | 911 | E | N/A | U-Groove Conventional |
| 1970 | Porsche | 911 | S | N/A | U-Groove Conventional |
| 1970 | Porsche | 911 | E | N/A | U-Groove Conventional |
| 1969 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1967 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1966 | Porsche | 911 | — | N/A | U-Groove Conventional |
| 1965 | Porsche | 911 | — | N/A | U-Groove Conventional |
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