My Prius started shaking pretty bad when the ICE is running. This morning I got the codes read and it came as Cylinder #1 misfire. I figured the coil pack is going bad (as is known to happen) so I swapped #1 and #2. The misfiring actually got better for about 30 minutes, but it finally happened and the CEL flashed again. So I took it to get the code read but he said the only code is still #1 misfire. Perhaps the ignition coil is OK then? I bought a new spark plug, maybe the plug has gone bad. The plugs only have 45k miles on them. I'll swap it out and see what happens. Any other suggestions on what I should do to diagnose the issue? It seems to be slowly getting better...this afternoon it was much better than this morning but still shaking sporadically. Thanks!
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.
No, I pulled the coil and stuck a paper towel down in there...it's dry. A small amount of oil but that is it. I guess I'll try replacing the plug.
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.
No, I had assumed if the misfire moved to #2 there would be codes for #1 and #2 both. I will disconnect the battery before starting the car next time. Thanks
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.
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 guess I should follow up. I put in Lucas injector cleaner when I first went to the auto parts store to pull codes. A day after my last post, the problem went away and hasn't come back. So I guess an injector was clogged.
I just checked the database and those are Sigourney Weavers fingerprints, that's an alien baby, named... E10
