Misfires, rough idle, vibrations
 

04 MT 60k miles. A little while back coming out of my neighborhood and turning onto the main road while accelerating I got a big loss of power, and misfiring in rotor 2. Took it to the shop, they replaced 4 plugs and said they were fouled, and it now it's fine. Drove it home, all good. Have been busy the last few weeks and didn't get a chance to take it out, it sat for about 2 weeks in the cold garage. Battery hooked up to a battery tender trickle charger.

Well took it out on the same route, as soon as I got on the main road and start accelerating, same issue. Power loss in low RPM when accelerating. Now this time I didn't see the flashing CEL and the CEL was not on, but I pulled a p0302 (pending) code. Now when I start it, I get a lot of vibrating during acceleration, and a ton of smoke coming from the tail pipes, dripping what looks like water, and a bad smell. The acceleration sounds very rough, not smooth at all. Same sort of symptoms before I took it in when they replaced all the plugs.

So anyway I'm thinking maybe coils? The shop replaced 1 a while back (I know this is ill-advised around here), I ordered 3 I'm going to replace myself. My question is, considering the plugs are new with ~15 miles on them, should I need to do anything with the plugs? Should I replace the coils first then try it? Or should I pull the plugs and clean them before even trying to start it? (not much experience under the hood if you couldn't tell).

Plugs are probably fine. I would just do the coils and see where that gets you. I bet its the coils. Everytime I had those symptoms as you described, I would replace both (plugs and coils) and it would be fine.

Thanks appreciate the input. Coils should get here tomorrow. Just wanted to make sure, no chance these new plugs were fouled up and need cleaning/dried off or anything.

Another thing I thought of; gas tank may have some stale gas in it. 6 months old at least. It's about 50% full atm. Is there an easy way to drain it? I've read on this forum about using the pump but apparently it doesn't drain it completely. Concern being; I wonder if water in the gas tank may be a contributing factor (along with weak ignition) to these symptoms?

6 months you should be fine. Car should start and idle. I would wait for any WOT throttle pulls until you have filled up.

Yep it was the coils. Starts and runs like new now. Thanks for the help :worship:

Great news.

For testing purposes next time you can by a HEI tester for like $5-$15 and hook it up to each coil one by one and when the spark doesn't jump the gap, you have your bad coil.

Also, in my experience a car will run 99% normal with a bad trailing coil and shitty with a bad leading coil. So you could always swap the trailing and leading coil in each rotor and see if the problem goes away. If it does, you know that one of your trailing coils (previously in the leading position) is bad.

But its all solved now so you don't have to worry about it for 30k miles