P0303 - Cylinder #3 Misfire Detected

[d4rkf1ber]

Well I need help / guidance on this. Yesterday I posted the following:

http://www.saturnfans.com/forums/showthread.php?t=89795

Today I got to another Autozone and they were able to read it. I read the machine and it said:

P0303 - Cylinder #3 Misfire Detected



My problems just started yesterday. However note that about 2 months ago I changed and did the following:

Changed ECTS
Changed Oxygen Sensor
Changed PCV Valve

Did the Mystery oil cylinder thingie as well. Along with regular oil, oil filter and air filter change.

Things were going good since I did all of this for a couple of months now.

Yesterday it started acting weird, as I described in the post. Kinda twitchy, jittery or something.

So, now I have more info thanks to the computer. But to be honest I cant say I know the best and cheapest way to proceed.

I need guidance on the easiest and cheapest things to try first.

I have done some reading and I know the following things are common suggestions:

Check and changed spark plugs - Consensus recommends NKG V I believe?

Spark plug wires? This I just am not sure about, don't know what to check or order from Autozone.

EGR valve? Again not sure how to check it or replace it yet.

Compression tests? Is this hard to do? Expensive equipment? I will ask father in law, retired mechanic for help on this.



So best order to do these things? Quickest and cheapest things are my friends since this is the worst month of the year to have any added expenses.

Any help is going to be greatly appreciated! I will keep reading and see if I can figure some of this out on my own in the mean time.

[redkees@msn.com]

How long since your last tune up?

If it's been a while maybe it's time to install new plugs and plug wires.
Clean any cororsion off the coil tower tips, that could cause the misfire too.

If you detect oil in your spark plug wells then a new cam cover gasket is in order. Review the how to library; do a search Wolfman has a great how to post there.

[madpogue]

^^^^ Ditto. If the problem persists, remove and exchange the two coil packs with one another. After that, the problem will still be a P0303, or you'll instead get a P0301, which is cylinder 1 misfire (the tower that used to serve #3 now serves #1). If the problem indeed moves to #1, that coil tower needs to be cleaned further, or that coil pack is just bad.

You might also have an injector problem with #3. When you remove the plugs, smell each one, and be esp. sensitive to the smell of unburned gasoline. If you do smell unburned gas on #3, that injector could be leaking, soaking the plug.

[prioris]

Recently got P0303 code on 1999 Saturn Sl1. I had to drive 70 miles with the engine sputtering. Made it home.

Found the problem to be spark plug wire. Wire on cylinder #3 was rusted and fell apart when pulled on. Will get it replace. Glad it wasn't a major problem.

Given the age of the car, the wiring connections seem the most vulnerable.
Any other likely wiring connection to get rusted ?