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2005 SRX Code P0303, Bucking

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It's been a while since I've posted here

after the '94 Seville puckered out.

But my father's '05 SRX (6 cyl) intermittently

bucks and the engine light just lit up, with

a P0303 code. It has 70,000 miles. Guess I'll

start with the spark plugs and wires. Any

other suggestions? Can injector cleaners cause

harm? Thanks.

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Cylinder misfire. How often does this happen? Only when cold or only when hot?

You can confirm your first guesses for wires and plugs when you examine the ones in there as they come out. If you see worn resisters on the plugs that would tend to confirm it was a plug issue. Perhaps a coil pack issue, or was the 05 coil on plug?

You are probably on the right track with wires and plugs, but any extra timing chain noise? There have been a few reports of timing chain issues along the way, so that would be my only longshot concern.


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Thanks for the reply Bruce.

It bucked just twice over a 60 mile trip.

Once while going up a hill, another on the

highway. The engine light tripped on both

occasions then went off.

It appears to occur when the engine is hot.

I just took it for a 10 mile test drive

(25 degrees outside) without incident. Very


There's no timing chain noise that I can


It appears that it's quite a job to get these

spark plugs changed. The intake manifold has

to be removed? Holy smoke! So if we take it

to a shop, we should have them inspect the

plugs. If there's nothing obvious with them maybe we should have them change the coil pack(s)($70) and injector(s) as well, since it's such a hassle

accessing them.

About the spark plugs, are they platinum or iridium? Rock auto doesn't offer wires, so

it looks like the ignition coil plugs right

into the plug.


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Code P0303 means the number 3 plug is the one that is misfiring...

The plugs are now 7 years old and it has 70,000 miles on it.

My guess is that it just needs new plugs.

If it was an injector, I think it would also have a code for that.

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  • 1 month later...
  • 1 year later...

Finally got around to changing the spark plugs at 87k.

The Cylinder 3 plug was particularly mucked up on the electrode, which

was most likely the cause of the misfire.

I decided to replace the plenum gaskets with felpro, even though the original

metal based gaskets looked ok.

It was about a 2 1/2 hour job to replace the plugs. I also replaced cyl 3

coil just in case.

The SRX is running great, and the tranny is especially smooth after filling her

up with Royal Purple.

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  • 1 year later...

I have just gotten my first Cadillac, a 2005 SRX with a V8 with 173,000 miles. I bought it from a dealership that did a quick turn around, which is why I got it cheap, and why nothing was done to it before selling it to me, other then cleaning it, which they did a good job.

Right away I got a message for coolant, oil change, and transmission fluid change, which I did.

Current status: Slight squeeling, which means change the belts, and I have hesitation and the check engine light is on, to which my dianostic tool tells me number 1 cyclinder is misfiring. No surprise, as I got a CarFax report, and it showed that at 71,534 miles, as it first entered California, it failed smog twice, then has passed ever since. I assume that the plugs were changed at that time, which means I should do that now as well as the belts.

Now comes the question, I am a do it yourselfer, but I can't even spot where the plugs are, no less remove them. I looked on YouTube and see a guy doing a V6, and the engine looks different for the intake on top. I want two swap the coils on two of the plugs to see if the misfire follows the coil or stays on number 1. Should be simple, but I can't even see that from looking down on the engine.

And with the belts, do I have to remove enough things from the radiator to get a clean shot ata the belts?

This is a learning process for me on the newer vehicles, as the newest one I had before this was a 2003 Mishubishi Montero Sport, and that required removing the top plenum to replace it's spark plugs. Took a weekend on that as I took it slow and easy, which is what I plan on doing with my brand new, to me, SRX.

Any help would be appreciated.

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It'd would be best to start a new thread to get help and answers. A search for north star spark plug change or coil removal would probably answer your questions.

Good luc .

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