Misfiring issue

Any water around the spark plugs? There are several threads on this topic.

 

Water and alot of people have spilled oil while filling the oil up right there and it leaked into the sparkplug well.

There's a TSB to replace the foam water dam right above the cylinder head to prevent water from gushing over and under the dam when it rains and drip on the cylinder head gets into the wells and shorts the plug out to ground.

search:

lusciousgarage.com repair blogs. They mention it.

 

Each time that you make a change, do you also disconnect the 12V battery for a few minutes, to clear the DTC logged by the engine ECU?

I agree that a misfire may be caused by either an ignition or a fuel injection issue so you need to investigate both.

 

It also may take some time for the DTC to log. For example, some DTC are not logged until the problem persists for two engine starts. So it would be good to clear the DTC so that you'll know when the new DTC is logged (based upon seeing the check engine light appear.)

 

First start with replacing all spark plugs, not just one. We had many cases with knocking badly engines, even not starting -caused by bad spark plug. Misfire could be shown on any Cylinder, but does not mean that the wrong one. Spark plug is recommended to be replaced at 120K miles. Don't put fancy sparkplugs, just the original.

 

Maybe it is a bad tank of gas!!
Try some Berryman B-12 Chemtool!!

 

I've got the same problem. Same cylinder. It's ugly. The plug was uglier when I pulled it. About 5K miles on it as far as I can tell from previous service record.



I replaced the plugs but I still get the misfire. I haven't tried swapping the coils yet.

I'm concerned those are metal deposits on my plug.
The other plugs were perfect:

 

I think that the excessive black deposits are from engine oil leaking into that cylinder. A cylinder compression test or leak down test would probably show very poor results in that cylinder.

 

Yes, if it feels and smells like oil.
Could be just running VERY rich from a stuck injector too.
In that case, the plug tip would probably smell more like gas than oil.

 

Sweet tap dancing Jesus

Ive seen fouled spark plugs in my watercraft, my atv, old old abused engines with carburetors, but never seen one that bad on even a very badly abused modern EFI engine!

 

I'm double/cross-posting here (I have more info under the "intermittent CEL" thread title.

But here's another #1 plug from a 2008 Prius. This one has 340K miles on it.


Cyl 2 wasn't a ton better, but at least it had all of it's insulator porcelain on it.

 

I had a similar issue on my 2007. I just cleaned the injectors with some carb cleaner and the issue went away.

 

I just checked the database and those are Sigourney Weavers fingerprints, that's an alien baby, named... E10