Table of Contents
- 1. What Is a Cylinder 4 Misfire?
- 2. Signs of Cylinder 4 Trouble
- 3. Causes of Engine Misfire
- 4. How Serious Is This Fault?
- 5. Diagnosing with iCarsoft Scanners
- 6. Steps to Fix Misfire Problems
- 7. Repair Costs in the U.S.
- 8. Tips to Prevent Future Misfires
- 9. Why Use iCarsoft for Diagnostics?
- 10. Common Questions About Misfires
- 11. Protect Your Engine from Misfires
1. What Is a Cylinder 4 Misfire?
Experiencing engine shake or loss of power? You might have a P0304 Toyota code, also called a cylinder 4 misfire. This OBD-II trouble code means cylinder 4 isn’t firing correctly, risking engine damage. Here’s what causes it and how to fix it using tools like the iCarsoft CR Eagle.
2. Signs of Cylinder 4 Trouble
Common signs include:
- Check engine light on dashboard
- Rough idling or vibrations
- Weak acceleration
- Poor fuel economy
- Occasional stalling or hesitation
3. Causes of Engine Misfire
Possible causes include:
- Faulty spark plug or wiring in cylinder 4
- Defective ignition coil
- Fuel injector clog or leak
- Low compression from worn piston ring
- Vacuum leak disrupting air-fuel ratio
- Faulty ECM sending incorrect signals
4. How Serious Is This Fault?
Driving with a misfire risks catalytic converter damage, higher emissions, and long-term engine wear. Address promptly.
5. Diagnosing with iCarsoft Scanners
Using an OBD-II scanner like the iCarsoft CR Eagle or CR MAX:
- Connect scanner to OBD-II port
- Select vehicle make/model
- Read P0304 code
- Check live data (injector, coil performance)
- Clear code after repairs
6. Steps to Fix Misfire Problems
Repair steps:
- Replace spark plugs or wires
- Test/replace ignition coil
- Clean/replace fuel injector
- Check compression
- Repair vacuum leaks
- Update/reset ECM
7. Repair Costs in the U.S.
Typical cost: $150–$600 depending on parts and labor. Example: spark plug $50–$100, coil $100–$300.
8. Tips to Prevent Future Misfires
- Replace spark plugs every 30,000 miles
- Inspect ignition coils during tune-ups
- Clean fuel injectors yearly
- Check compression every 60,000 miles
9. Why Use iCarsoft for Diagnostics?
- Full OBD-II compatibility
- Live data for accurate diagnosis
- User-friendly interface
- Quick code clearing
10. Common Questions About Misfires
What does P0304 mean?
It indicates a cylinder 4 misfire, where combustion fails in that cylinder.
Can I drive with a P0304 code?
Short distances may be possible, but prolonged driving risks engine damage and catalytic converter failure.
How do I fix a cylinder 4 misfire?
Use an OBD-II scanner to diagnose, then repair or replace faulty components like spark plugs, ignition coils, or fuel injectors.
11. Protect Your Engine from Misfires
Quick diagnosis with tools like the iCarsoft CR Eagle can prevent costly damage. Regular maintenance ensures smooth performance and avoids repeat P0304 Toyota issues.
