2004 Toyota 4Runner sputters on start

My car sputters, coughs, etc when staring in am, but will correct itself after 1 minute, but does have some slight sputtering when going up hills. Other than that it runs good! My car has been in 2 different Toyota dealership repair shops for this problem. The engine light always says “cylinder 2 misfire.” The plugs have been replace, the coil also, and now the fuel injector too. The problem has not been solved, but they did tell me I have carbon build up so put in premium fuel which I had already been doing along with different fuel and injector cleaners, all to no avail. Any ideas?

Premium gas has no more detergents than regular gas. So you’re wasting your money.

If you’re talking about carbon deposits on the intake valves, give this product a try.

Tester

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Putting Marvel Mystery Oil in your gasoline may gradually help expel carbon buildup, too.

Is it a 4 or 6? The 1 time I had a misfire with my '87 Toyota pickup it was obviously running really roughly. Inspect the plugs yourself if you think you have carbon buildup.

Is it caused by too-rich a mixture? I had difficult starting when my choke failed. Does it backfire?

Are you kidding me?

Seafoam is made in Eden Prairie, Minnesota. And it Works!

Marvel Mystery oil is made in Chicago, Illinois. I’ve never used it. No reason.

As they would say up north!

“You ain’t no Minnesotan!”

Tester

Dude! I live in Duluth! Minnesota! Up North! Of you!

I think you are wise to focus on the misfire, as that’s probably causing the symptoms you are noticing. Misfires going on for an overly long time can damage the cat too, so another reason to get to the bottom of the misfire. The good thing about a single cylinder misfire is you can rule out everything except stuff specific to that cylinder. So it’s very unlikely to be a fuel pressure problem, or a clogged cat problem, or an O2 sensor problem, or a throttle position sensor problem, fuel filter problem, egr problem, etc.

Whatever it is, it pretty much has to be from among these, affecting that cylinder only

  • spark plug or plug/gap
  • spark plug wire/coil
  • fuel injector or (much less likely) obstruction in the fuel path to that injector
  • compression
  • valve clearance incorrect
  • obstruction in intake or exhaust valve

Since you’ve replaced the first 3 already, I suggest it is time to do compression and valve clearance measurements comparing that cylinder to the others. I’d probably ask for a fuel trim measurement too.

@RandomTroll. The 4Runner came in a V6 or a V8 in 2004. There was no 4 cylinder in the 4Runner
I had a similar symptom to the OP in a 2000 Ford Aerostar 4.0 V6. The problem was ultimately traced to a hair line crack in the cylinder head. I was fortunate that the Aerostar was still under warranty. The coolant leaking in had scored the cylinder wall. Ford replaced the engine. The problem was confined to just one cylinder.

You have cars that far north? I thought you were confined to dog sleds and reindeer.

C’mon, you know they use snowmobiles 11 months of the year. :grinning_face_with_smiling_eyes: