Cars are complex. Little changes can make a big difference and it may of for me.
So I was doing what little fixing I can do with my car. I had just replaced my front O2 Sensor. About two days later my engine starts shaking, which was not a surprise to me, I need new motor mounts.
The odd thing is when my check engine light stated to flash. Got the code (P0303) something about a misfire in my third cylinder. Read up on it, saw some big price tags if I let it fester for to long, so I tried to jump on it.
Of course it could be a million things, I went with what I was going to do anyways and what I could buy then and there. I got new spark plugs, wires, and coil packs. but the light persisted.

Does anyone think it at all possible that the shaking of the engine is throwing the error?
Or is another problem just cropping up?
Or is it my O2 sensor.

 

 

It didn't go away after I installed the new spark plugs or coil packs.
I just put on the top motor mount and although the engine is smooth as a baby's bum now, the error is still there.

I'm trying all the small or cheap fixes right now, cause it gets expensive fast.

I took off my valve cover and my seal is trash. it's leaking (although a little) oil into my spark plug er, "holes".
So that could be the and/or a problem.

I also read up that it could be my intake, or fuel injectors, but I'm a computer guy, not a car guy, so I can only google so fast about locations and how to's, you know.

p.s. The computer is shutting down the cylinder? That's good to know. Cause a new converter is a fair bit of money.

 

Oil leaking down the tubes where the spark plugs are installed can, if it builds up high enough, get wicked up between the spark plug boot and the spark plug, "shorting" the spark before it ever get to the end of the plug. Therefore not firing in the cylinder, and the car's ignition system detects it as a cylinder specific misfire. Check your old #3 wire's (2nd longest) boot end for swelling from oil absorption and evidence of oil presence.

As for plugs, use should be using the stock plain old copper plugs, not anything else. No platinum, iridium quintuple electrode byzantium impregnated plugs. Unless you want to chase misfires that are a direct result of using the wrong plugs for this engine.

What rpm does it idle at at operating temp? Manual or Automatic?

Don't change more than one thing at a time while troubleshooting. You lose your ability to draw direct conclusions from the change.

 

Automatic.
It idles at about 800rpm

 

700-800 rpm idle for DOHC A/T, so OK there; likely no vac/intake manifold leaks,
How many miles on the car?.
What prompted you to replace your front 02? If it was a code, which one (Pxxxx format please)?

For clarification:
1) Do you ever have ONLY a solid SES light when the car is running? When? (pre O2 replacement, post O2 replacement, both? neither?)
2) Is the SES light always blinking while the car is running?(Did that start before or after you replaced the O2 sensor?)

A) What front O2 sensor did you use as the replacement (brand and part number--no I'm not implying you used the wrong one, there are some known to be happy in these engines, and others, well......)
B) Did you have the P0303 before replacing the front O2?
C) Did the engine start shaking right after you replaced the front O2? Or was there a window of time with new plugs, wires, coil packs and new O2 sensor where the SES was not lit and the engine ran smoothly..? Did you refill your gas tank after the O2 replacement and before the shaking?

Not trying to play 20 questions; just like to have all the pertinent info up front so we can troubleshoot down the right path.

Remove the spark plug boots from the plugs and make surf there is no oil still collecting in the spark plug wells.

 

Miles: About 130k (130,000)

The SES light was solid with a "bank 1 Sensor 1" code
After changing the O2 Sensor with (Part# 11027 Bosch Oxygen Sensor) it ran smooth for a couple days before it started to shake.

At this point it has a flashing SES light with the p0303 code. It flashes sometimes, usually around 40-45 mph it seems. It's either solid or flashing.

After changing my PVC valve and hoses and the head valve gasket, I have found no more oil in my spark plug wells. No more oil specifically, I still have to remove the little that was into there from before though.

 

Sounds about exactly the mileage that the O2 sensors in the front give up the ghost. I find Bosch sensors to work like crap in my Saturn's. I use the Denso sensor that is equivalent to the AC Delco sensor which in fact is a rebranded Denso or may actually say dancing on the outside. You still have not indicated what type of plugs you are using. If you do not have the stock NGK good old 5643 copper plugs, go spend $6 and put them in. And get that oil out of the spark plug Wells. And be sure to soak all the oil out from inside the boot where the plug connects.

I assume you meant valve cover gasket not head gasket.

 

And and for the record, that behavior is exactly what Bosch front oxygen sensors do in my cars. That's why I run the densos.

 

Yeah, Valve cover gasket.

I got NGK copper plugs.

Should I just take the cover off and stuff a microfiber rag down the wells to get the oil out?

I'm going to check the fuel injectors to make sure they aren't clogged or anything and get a new O2 sensor.

Hopefully it will fix the problem, cause besides this, all the stuff I've done to my car has made it buttery smooth in other areas. Can't wait to see how it runs after I fix this.