2001 Toyota Tacoma 2WD 2.4L 4cyl. Just under 100k miles.
Looking for guidance on narrowing down the culprit for a misfire. Here's the pattern:
Truck runs fine from a cold start, and continues to run fine once it warms up.
But once you stop, shut the engine off, and come back to restart it while the engine is still warm, it'll misfire/run terribly. Strong vibration, low power, hesitation, flashing CEL.
If you let the engine cool off completely and restart it, it's fine again.
Every once in a while, it'll temporary resolve itself once its started misfiring.
- It's throwing code P0301 (cylinder 1 misfire) consistently.
- Only once it threw a P0171 (lean) after I had to hobble home on a 35 minute drive after it started misfiring (this was before I realized that if it cooled down it would resolve itself temporarily).
Things I've done so far:
- Made sure the gas cap was tight
- Replaced all 4 spark plugs (Denso Iridium 3324)
- Swapped 1st and 4th coil (no change)
- About a month ago I cleaned the MAF sensor, and I cleaned it again today
- Cleaned the throttle body
- Checked/blew out the engine air filter
- Visual check for vacuum leaks (didn't identify any). Don't have a smoke machine may pick one up.
- Fuel trim levels when it's cold and not misfiring
- Footage of when it is misfiring
- Fuel trim levels of when its misfiring
In researching misfires P030* codes, it seems like there could be a lot of culprits, so I'm trying to narrow it down.
Questions I'm throwing out there:
- Based on the symptom of it only misfiring once warm and restarted, where would you look first? (then second, then third?)
- Are there other routine 100k maintenance things that could possibly resolve the issue that I can try? E.g. the spark plugs - they were due anyway so I didn't mind throwing the money at them to see if it fixed the issue. Looking for other "low hanging fruit"/should be done anyway type things.