P0300 P0301 P0302 P0303 Cylinder Misfire. Shaking on startup Help!

I would check spark plugs first, and drain engine oil to see if milky if we you're due for oil change.,
A leak down test should tell you if you have a blown head gasket...

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You generally learn something from whether a single-cylinder misfire shows up or you get four at once, but it's not like one case has to be something more severe than the other.

Misfiring in a single cylinder or two usually indicates you have some kind of issue specific to a cylinder or two. Misfiring across all cylinders usually indicates you have the sort of issue that affects all of them.

 

Coils and Injectors are unlikely to be your issue, at least not at the same time. The coils and injectors are very expensive for this car and should not be shotgunned.

 

Not sure if it's "best", but for the cooler, "Oxi-Clean Versatile Stain Remover", mixed with hot tap water, as concentrated as you can manage, worked for me. I corked one end. poured it in, prop upright in a corner of the laundry sink, let sit for about an hour. It'll bubble up, then subside. Rinse and repeat about five times.

I would try a leak-down test. A competent mechanic familiar with the process is probably the simplest approach

Don't do that.

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Oven cleaner is the quickest. Along with a pressure washer.
The pressure washer clears it out, and the oven cleaner cleans out the carbon and soot.

If it is super clogged, it will probably take several passes to get it cleared.
Wear gloves for the oven cleaner and spray it at both ends a few times to make sure it gets
all the way in. Let it soak for 30 minutes or so then use the pressure washer to clear it out.

I almost forgot... for the intake, Gunk, and a small caliper brass bore brush in a drill.
It will clear out the 4 passages on the intake manifold really fast.

 

Oh, neglected to mention: I would only use caustic cleaners (Oxi-Clean, or even more caustic Oven Cleaner) on the (stainless steel) EGR cooler. The EGR valve is mostly aluminum, and will likely react with caustic solution. Might just be cosmetic, but not sure. Ditto for the intake manifold: mostly plastic, but it does have metal embeds that react adversely. The EGR pipe (between EGR valve and intake manifold) is also stainless steel, but is very easy to clean, without caustic cleaner. I think it'd be ok to use though.

 

10/1

Yes for a couple months but you will also know it was a head gasket. Its a pretty cheap and easy hg diagnostic but in the end things may be far worse, costing you a radiator, cabin heat or even an engine. Most of the time all the previous expense will be wasted.

 

Just use a pressure washer and save the cleaning solutions for other jobs.

Good luck and keep us posted.

 

The oil puddle in the intake manifold is normal.

Since you've got everything apart, and changing out the PCV valve, you should install an oil catch can.

But if you have a failed head gasket, it might be too late.

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Did you clean the egr? I’m seeing all over this can cause the knocking and misfires