A 2001 Toyota Tacoma ran normally from cold but misfired after being stopped and restarted warm. The recurring code was P0301; P0171 appeared once.
What narrowed the search
New spark plugs did not resolve the complaint. Swapping ignition coils between cylinders 1 and 4 left the misfire on cylinder 1. A responder suggested investigating that cylinder’s injector rather than continuing to assume an ignition fault.
What the owner reported
In a September 2019 follow-up, kcub said the issue was resolved after fitting four refurbished injectors. The owner also reported a crack in the removed cylinder-1 injector. AI4Car has not independently inspected the vehicle or verified that conclusion.
What to take from the case
Record the conditions that trigger an intermittent fault and whether a controlled test changes its location. A cylinder-specific code identifies the affected cylinder, not the failed component. This case does not justify replacing every injector on another vehicle. Fuel-system testing involves pressure and fire risks; use the correct service procedure and qualified assistance.
Author follow-up · not independently verified
For information, not a diagnosis or repair instruction. A reported result may not apply to your car. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This is an editorial interpretation of a public discussion. Replies, votes and an accepted answer do not prove a diagnosis. An author-reported finding or repair has not been independently verified by AI4Car. Illustrations are conceptual. Read the content limitations.
Credits & reuse
AI-assisted adaptation by AI4Car of the contributions below on Motor Vehicle Maintenance & Repair Stack Exchange. We shortened and reorganized the discussion, paraphrased its text and added educational context. These are reported experiences, not independently verified repairs. The contributors do not endorse AI4Car.
- Question: Narrowing down cause of misfire when engine is warmBy kcub · CC BY-SA 4.0
- Answer: Narrowing down cause of misfire when engine is warmBy Pᴀᴜʟsᴛᴇʀ2 · CC BY-SA 4.0
- Comment / follow-up: Narrowing down cause of misfire when engine is warmBy kcub · CC BY-SA 4.0
This adapted article text, including AI4Car’s additions, is available under CC BY-SA 4.0. Reuse is permitted under that license with attribution, an indication of changes and ShareAlike. This notice excludes the separate illustration, site design and user comments. The source revision history remains available at Stack Exchange.
Illustration: AI-generated for AI4Car; a generic conceptual view, not a photograph of the reported vehicle or a manufacturer’s diagram. Content and licensing policy.
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