Bad gas?

[sjowol]

Man I just signed up and already so many questions... sorry

Last week I got gas at a gas station I usually never go to, it looked like they just replaced their pumps as the old ones were still standing on the side.
Probably 10 minutes after filling up my (2000) LC (with approx 180K miles) started sputtering, this gradually got worse and the next day while driving the warning lights came on: Trac off, VSC Trac, and check engine.

This is when I started thinking I had some bad gas... maybe some water in it or something? I got some gumout at the local autozone and added it to the tank, the next day there was significant improvement my wife took it to autozone to get the warning read and told me it was a random misfire. again making us think it is the gas. also that day the warning lights went off BUT after I filled it up again, the problems started all over, not as bad at the first time but enough to trigger the warning lights again. (maybe stirred something up? so more gumout and looking on the forums.
That is when I bumped into several treads saying it might be the ignition coil or the spark plugs, I ordered an OBD2 reader but (ofcourse) before that arrived the warning lights went off again.

When the reader arrived I checked and it had 2 stored warnings: p0300 (random misfire) and p0307 (misfire in cylinder 7).
The car is driving fine, I sometimes feel a tiny bit of stuttering still but nothing really bad.

So what do you guys think?
- was it just bad gas? if so would the gumout have fixed this or should I do more?
- is it the ignition coil going bad (I assume the one on cyl 7) and should i replace this?
- should i also replace the spark plugs?
- when looking for the iginition coils there is also the Spark Plug (Coil-On-Plug) Boot, would replacing this maybe be sufficient or what exactly are these (I was thinking of changing whole coil on 7 and the boots on all the others)
- how hard is this to all do myself?
- What brand & type coil and plugs do you guys recomend? my shopping cart now has:
DENSO Part # 6731303 Coil on Plug x1
DENSO Part # 6718184 Coil On Plug Boot Set x1
DENSO Part # 3297 {#SK20R11} Iridium Plug; Iridium Long-Life x8

Any advice would be greatly appreciated. Thanks!

 

[tahoejoe]

I've replaced a couple ignition coils on mine after getting P030X (where X is the cylinder #). Process is easy - takes 15 minutes. I believe all you need is 10mm socket. Easy to swap coil to another cylinder and see if the trouble code changes to the one you moved it to. If it does then that confirms that the coil is bad. Replaced with Denso 673-1303. I keep a couple spare coils on hand just in case.

 

[sjowol]

Ha good, got the right one in my cart then, but if it is a faulty coil would the warning light just go out though? guess it won't hurt to get a spare one in the car just to be sure i guess. is there any reference you can point to that shows what cylinder is what number? no clue which one 7 is to be honest.
Thanks!

 

[Sandroad]

Odd numbers on the drivers side and even number on the passenger side, both start numbering fom the front. #7 is rear drivers side.

 

[skhochay]

it is not a gas for sure , just coincidence , but have you done anything to the car in that week like messing with dashboard? or replace spark plugs? give us a history for a last month.

 

[hankinid]

I would think water in the gas may cause a misfire. Given you've got the coil issue covered, you might try adding HEET to the tank to absorb any remaining water. I'd also replace the fuel filter, and maybe carry a spare, just in case.

The old rule of never getting gas at a station when the tanker is unloading, comes to mind.

Steve

 

[Xetabur]

I had this exact same problem yesterday. It's at the shop as we speak. It's probably a coil pack.