I just went out to my car tonight and it's idling rough and when I accelerate it seems like it wants to stall and the check engine light came on. About a month ago the check engine light came on and the code read cylinder 3 misfire but the car was running with no problems at the time. It has new plugs, wires, and fuel filter in the last 6 months so what can I do to diagnose the problem on my own?

Hello,

Check the terminals on your coil packs.
Corroded terminals haunted me for weeks.
They should be shiny clean.
If they aren't, clean them up, and take a test drive.........If you are running strong again, you need to replace whichever coilpacks have corroded terminals, as they will continue to corrrode.

Later now,
Clint

I forgot to mention I even had the coil packs replaced when I had a tune-up done. When I went out to my car later I could smell fuel or bad fumes but I'm not sure if that was caused by the rough idling. I even tried adding some Redline fuel system cleaner and that didn't help.

I have to go to work tomorrow so this isn't good.

Get the code.
May be something totally new.
Maybe a MAF sensor..... Try shooting some Carb Cleaner through the sensor.
EGR valve.... Same thing...Carb Cleaner, and working it, in and out.
Had a 2000 here that had a MAF sensor go bad..... messing with the wires proved the connections to be bad... Only cure was to replace the sensor.

Later now,
Clint

Go to autozone and get a scan. They do it for free.

Also check the battery connections. Loose/corroded battery connections wreak havoc on our cars.

What is good for cleaning the ignition coil terminals?

Steel wool or sand paper? I'm assuming sand paper.

The same happened to me time ago, and with new spark plugs, they take out every plug and there it was, dirt on one of them, solved problem.

Same prob on my dad's Marquis when I took it to Florida. Got it all tuned up for the trip then an hour after we leave to come back it idles real rough. Shops all closed but we found out the place my dad had do the plugs messed one up a little and it ended up connecting the tip to the rest of itself because the tip was bent.

Check all your wire connections as well one maybe loose.

Thanks for all your suggestions. I tried cleaning the battery terminal cables in the morning (one is completely rusted and even chipped with no metal showing at all). I'm taking it to AutoZone to get it scanned tonight when I get off work so keep an eye on this thread and I'll post the code they give me.

Anyway I need to change that battery terminal connector even if that's not the problem, how exactly do you change that metal piece connected to the terminal cable (I probably need to change the entire cable, right)?

Hello,

If your terminals are clean, don't do anything to them. I believe they have a protective coating that steel wool and sand paper will remove. If they are corroded, they need to be replaced, or cleaned on a regular basis, as they will continue to corrode. I know from experience.....
http://home.comcast.net/~crimpton/IM004406.JPG

Later now,
Clint

Ok, I went to AutoZone and the scan showed 4 codes. Multple cyclinder misfires and manufacturer fuel/air remixer? The car engine is shaking at idle and it sounds like it's going to stall.

I asked him what would cause the manufacturer fuel/air remixer problem and he said I have to take it to the dealer to get that code? Ugh..more money down the drain.

Could it be a bad air/fuel sensor on the car causing the problem (I'm not even sure if cars have one) haha?

Hello,

Give the code numbers.
We may be able to help you if we have the numbers.... AutoZone should have told you.

Later now,
Clint