P0304 Toyota -

Question

Same issues as this user, except now I'm missing all the time. The P0304 code has not changed. I've replace the coil pack, spark plug, and spark plug wire. I'm also running BG44k in a full tank of fuel at this time.

I have 2005 4Runner. Check Engine lights came on and mechanic changed coil and spark plugs. Now the car starts a little rough in the morning and the check engine light came back. Mechanic checked the code and it was P0304 so it was misfiring in Cylinder 4 again. Drove it for a week and check engine light came on. 2 Days later the check engine light went off. Check engine light is back on and car is still runs rough when first started up. Then it runs like a champ. I have had the car 2 years, 166,000 miles and no problems. No overheating, no other problems.

Read more: https://www.autocodes.com/qa/31485/p0304-toyota#ixzz3L9M9pfHJ

Answer 1

P0304 Misfire number 4 cylinder

If this misfire was a mecahnical condition it would misfire at all time , if it was the ignition related you would have the same event at all times, If this is injector, there are time especially when warmed it runs like a champ and intermittently there will be a misfire, You can not run a fuel injector cleaner hoping this will clear up. Injector are capable of one minute running great no misifire event and at otherr time there is a intermittent misfire. especially when it firs start up. This is a good indication that its connection may be poor and making proper contact. When the engine is cold or first started up it need more fuel than air, if the injector is not proper it stumbles when cold . as it warms up the fuel required is less.