P0304 MISFIRE ON CYLINDER 4

I used MAF cleaner on mine.

Pixel XL ?

 

I have a can of MAF sensor cleaner, can I use that?

 

MAF cleaner should be fine.

 

Thank you!

 

If you did not install iridium spark plugs, that was a mistake.

 

bosch iridium gapped to spec, torqued to spec

 

What? Ash? Could you post Pics of those old plugs?
I have had heavy ash residue on the electrode insulator from mixture too rich (wettish carbon soot), burning oil (oily carbon soot), and blown head gaskets (whitish fluffy deposit), and I've had the center electrode melt away and the insulator actually break off pieces (severe pre-ignition), but I never had that center electrode reduced to ash! You might Consider checking the combustion chambers and tops of the Pistons for deposits or signs of damage or impending failure with , say, a boroscope? (When my sparkplug insulators threw off chips, I was fortunate that the chips were small enough to pass out through the exhaust valve gap before impacting the piston crown or doing other damage, but that was just luck.) Good luck, mate!

 

I'm having a problem uploading pics, I don't know why it's showing up with a red X on the link.
The plugs were very burnt and the ceramic on the plugs had burn marks but the tips were still intact but burned.

 

Ok, if you mean a large blackened area on the porcelain ABOVE the metal base of the plug, that ring of soot is typically a sign that the rubbery gasket that pneumatically seals the porcelain with the center electrode to the outer metal threaded part that screws into the spark plug hole, has failed. Usually that gasket fails with cumulative time and use, and the carbon accumulation just means the plugs are old.
But the burned electrodes on the inside tips of the plugs is what concerns me, as those electrode tips directly reflect what has been happening in the combustion chamber. Ideal is a dry, light brown coating on the porcelain around the center electrode with no other signs of combustion temps that are too high or too low, and no sign of contamination with blow-by from worn rings, oil seeping past the valve stem seals, or coolant seeping into the chamber from a blown head gasket. (In the leaded-gasoline days, I had to sand blast off the lead accumulations that would show up as tiny little drops of condensed lead on the porcelain, but I digress.) my point is that if your spark plug tips look really ugly, you might want to look for the associated causes, and possibly also consider changing to a hotter or cooler range of spark plug to better fit your pattern of driving.
Good luck, and post the pics if you get a chance!

 

See if this works, all the pics are on photobucket. I can't upload them here and I'm getting aggravated
Daniel Negron's (dan05979) Story | Photobucket

 

I have a 2010 prius that was misfiring on cylinder 4 I ruled out bad spark plugs and coils by changing the spark plugs and moving the coil from cylinder 4 to cylinder 1. Still reading a misfire on cylinder 4 and still exhibiting the same shaking or shuddering when the engine RPM was low and under stress. I found this post and had the idea to just disconnect the harness for my EGR valve and that cleared up the misfire, the car runs smooth and does not miss(verified during a real time scan and drive). I plan on leaving it disconnected until I get around to cleaning the pipes. I would suggest using this as a means of diagnosis, thanks!

 

hey guys, i'm still getting a quick shuddering when I do a cold start up then goes away. Only when the engine is cold. It's very annoying.

 

Had all but given up on 2010 prius transmission shudder until I read catalinux post. Watched youtube video for cleaning manifold and copied step by step. No more transmission shudder. No more PO304 error code. Thanks Catalinux!

 

Hey Catalinux! A big thanks to you for resolving this issue that's been giving me a massive headache and a huge nightmare for the past 1.5 months. Hats off to you man. You are the man. . I wish I came across your post in the beginning of this issue so I could save so much time and about £1300 that I spent on Toyota new parts, tools and diagnostics costs. I had the same problem of engine juddering at low speeds and high torque but the only problem was there were no check engine warning lights or any DTCs which made it so difficult to diagnose. I owe you big time. Well done man Well done. I am surprised it was only those small bastard holes which you pointed out in the IM. My car drives smooth after almost two months of despair.

 

Is your car still running right? Has P0304 not returned after cleaning air intake manifold?
I’m having similar problem.
I’ve done all this:
-new coil in #4
-4 new spark plug
-new pcv valve
-cleaned mass airflow sensor
-cleaned EGR tube (new gaskets)
-cleaned intake manifold (new gaskets)
-cleaned oil in throttle body
- cleaned fuel injectors (swapped #4 & #2 hoping for P0302 code)
I’M STILL GETTING P0304 CODE!!
Plus I’m going through a quart of oil a week (I drive 500+ miles a week with Lyft & Uber)
So frustrated!

 

Did you find separate tubes from EGR inside intake manifold? Separate from the place that air comes from air filter? I cleaned my intake manifold but still have same shudder. Worried I missed a separate air space or something.

 

If you're burning a quart of oil every 500 miles, whatever cleaning you're doing isn't going to help. Save your money, you'll need a new engine.

 

i had a misfire P0304 yesterday out of the blue on our 2011 (wifes car). just 10k mi since my rebuild. this is what i found in my case. left is the new plug i got from AutoZ today and right is the plug i got from eba.y reseller.

"iridium" tips of all 4 old spark plugs look very similar in varying degrees of "erosion". gaps are more than 1.5mm. its a wonder its been running at all. for sure its a fake. on the 2nd smaller pic, u can tell the difference in the weld of the ground electrode. next time i'll just get it direct from denso online store. Amzn is no different.

 

Thanks I didn't even know that Denso has an online store. Looks like they have two actually, one of them is only for apparel! The parts store has sensors (MAF, MAP, O2, cam position, etc.), AC components, air and oil filters, ignition coils and a bunch of different wiper blades. Bookmarked!

 

Both plugs have the same part number? The old one does not look like an iridium tip