Checks, in order
- Spark plugsPull the plugs and look at the gap and wear. Replace them with the correct type and gap as a full set.easy $ · under about $50
- Ignition coilsSwap suspect coils between cylinders and see if the misfire moves. Replace any failing coil.easy $ · under about $50
- Throttle bodyClean the throttle plate and bore with throttle body cleaner. Carbon buildup causes a rough or hunting idle.easy $ · under about $50
- Fuel injectorsListen to each injector with a stethoscope for a steady click. A clogged injector can cause a misfire on one cylinder.medium $ · under about $50
- Misfire only when coldIf a single cylinder misfires on cold start and clears warm, check for coolant loss and run a block test, especially on 2003 to 2005 V6 trucks.easy $ · under about $50
Applies to: 2003 to 2009 4Runner with the 4.0L 1GR-FE V6 and the 4.7L 2UZ-FE V8, 2WD and 4WD. Engine specific items are labeled, and some issues apply mainly to early model years.
Tools and parts for these checks
Links below are Amazon affiliate links: as an Amazon Associate, toyotadata earns from qualifying purchases, at no extra cost to you. Confirm fitment for your exact truck before you order.
| ITEM | USED FOR | BUY |
|---|---|---|
| Bluetooth OBD2 scanner with live data | Reading and clearing codes and watching live sensor data | Shop on Amazon |
| Ignition coil | Swapping a suspect coil after the misfire follows it | Shop on Amazon |
| Spark plugs | Replacing worn plugs at the factory interval | Shop on Amazon |
The same problem on other Toyotas
- 4th Gen Tacoma (2024–present): Rough idle, misfire or shaking at a stop
- 3rd Gen Tacoma (2016–2023): Rough idle, shaking at a stop or misfire (P0300 to P0306)
- 1st Gen Tacoma (1995.5–2004): Rough idle, misfire or lean codes (P0171, P0174, P0300)
- 5th Gen 4Runner (2010–2024): Rough idle, shaking, or misfire with a flashing check engine light
- FJ Cruiser (2007–2014): Rough idle, stumbling or a misfire code (P0300 to P0306)
- 100 Series Land Cruiser / Lexus LX 470 (1998–2007): Rough idle, stumbling or a misfire code (P0300 to P0308)
Other fuel & ignition problems on the 4th Gen 4Runner
More 4th Gen 4Runner problems
- V6 losing coolant, cold start misfire or overheating (early 4.0L) (Engine)
- Frame rust or rusted suspension mounts (Frame & Body)
- Clunk, knock or wandering from the front suspension (Steering & Suspension)
- Sticky, melting or cracked dashboard (Body & Electrical)
- V8 timing belt service: when is it due? (Engine)
- Ticking or diesel-like noise on cold start (Engine)
All 16 4th Gen 4Runner symptoms in the interactive troubleshooter →
General guidance from owner experience. Confirm torque specs, fluid capacities and procedures in the factory service manual. Brakes, steering and anything structural: if in doubt, have a qualified shop inspect it before driving.