Description
Product Overview
Unlock the hidden potential of your Jeep's legendary 4.0L inline-6 with the iFJF 62mm High-Flow Throttle Body. The factory throttle body on 1991-2006 4.0L engines uses a restrictive 55-58mm bore that chokes airflow above 3,500 RPM — right where you need power for highway passing, towing, and steep grades. Our 62mm CNC-machined throttle body increases airflow by 15-20%, delivering 10-15 additional horsepower and noticeably sharper throttle response. Precision-machined from billet aluminum with a tapered bore, it's a direct bolt-on that works with your factory sensors, intake, and ECU — no tuning required.
Key Features
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62mm High-Flow Bore — Increases intake airflow by 15-20% over stock 55-58mm. Tapered entry smooths airflow for better cylinder filling across the RPM range.
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CNC Billet Aluminum Construction — Precision-machined from solid 6061-T6 billet. Far more durable than cast OEM throttle bodies prone to vacuum leaks around shaft bushings.
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10-15 HP Gain — 8-12 HP on stock engine, 12-15 HP paired with cold air intake and cat-back exhaust. Gains most noticeable 2,500 RPM to redline.
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Improved Throttle Response — Larger bore means less restriction at partial throttle. Feel the difference in tip-in response and mid-range passing power immediately.
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Direct Bolt-On, No Tuning — Uses factory IAC valve, TPS sensor, and throttle cable. Stock ECU adapts fuel trims automatically. ~45 minute install.
Compatibility
| Make |
Model |
Years |
Engine |
| Jeep |
Wrangler YJ |
1991-1995 |
4.0L I6 |
| Jeep |
Wrangler TJ |
1997-2006 |
4.0L I6 |
| Jeep |
Cherokee XJ |
1991-2001 |
4.0L I6 |
| Jeep |
Grand Cherokee ZJ |
1993-1998 |
4.0L I6 |
| Jeep |
Grand Cherokee WJ |
1999-2004 |
4.0L I6 |
Specifications
| Specification |
Detail |
| Bore Diameter |
62mm (stock: 55-58mm) |
| Material |
6061-T6 Billet Aluminum |
| Throttle Plate |
Brass (low-friction) |
| Sensor Compatibility |
Factory IAC, TPS, MAP |
| HP Gain |
10-15 HP (with supporting mods) |
| Installation |
Bolt-on, ~45 minutes |
| SKU |
FJ-JP-TB15 |
Installation Notes
- Disconnect negative battery terminal.
- Remove intake tube from throttle body. Disconnect IAC and TPS electrical connectors.
- Remove 4 throttle body mounting bolts (10mm). Remove throttle cable bracket.
- Transfer IAC valve and TPS sensor from old throttle body to new one. Use new gasket (included).
- Install new throttle body with supplied bolts. Torque to 12 ft-lbs in cross pattern.
- Reconnect intake tube, connectors, and throttle cable. Verify smooth throttle plate movement.
- Reconnect battery. Start engine and idle 5 minutes — ECU auto-learns new idle parameters.
Frequently Asked Questions
Q: Will this cause a Check Engine Light?
A: No. The 62mm bore is well within the ECU's adaptive fuel trim range. Factory computer automatically adjusts idle air control and fuel mapping. No CEL, no tune required.
Q: Do I need a cold air intake to see gains?
A: You'll see 8-10 HP with the stock airbox. Pairing with a CAI maximizes the benefit — CAI removes upstream restriction, 62mm TB removes downstream restriction.
Q: Will this hurt fuel economy?
A: At cruise (light throttle), the larger bore doesn't affect consumption. Under acceleration, you'll use slightly more fuel making more power. Most report 0-1 MPG change in mixed driving.
Q: Too big for a stock 4.0L?
A: 62mm is the sweet spot. Larger bores (64mm+) cause part-throttle drivability issues and reduce low-end torque. 62mm provides best airflow/velocity balance.
Q: Fits the 2.5L 4-cylinder?
A: No — 4.0L inline-6 only. The 2.5L uses a different bolt pattern and would be over-bored at 62mm.
Q: Boring stock TB vs this billet TB?
A: Boring removes material but can't fix worn throttle shaft bushings (common vacuum leak source on high-mileage 4.0Ls). Our billet TB starts fresh with precision bearing surfaces and tapered entry bore.
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