Cylinder 1 Missfire. Replaced Spark Plug, Worked fine for ~5 miles, Now same problem

[bspeed3]

Hello everyone,

I've got a 2007 Speed3, 60k miles.

A couple days ago my CEL went, and I pulled code P0301. The car had been idling somewhat rough. I took off the intercooler for the first time since buying the car at 50k miles.

First thing I noticed was that the cylinders appeared to be mislabeled. Facing the engine from the front of the car they were labeled, from left to right:

4 3 2 1

I pulled the plug connection on the left most cylinder, which was labeled 4. It sounded the same so I assumed the last person to own the car had mislabeled it, and they should actually be numbered:

1 2 3 4

In either case, I replaced the plug on the left most cylinder. The idle became smooth again, the CEL turned off. I drove about 5 miles and the exact same problem returned. I'm thinking it must have something to do with the connection of the spark plug, or the coil piece that makes the connection into the engine, from the wiring(sorry can't remember its name off-hand).

Anyone have any advice for me?

Thanks!

 

[Russm]

There is a small spring in the plug boot that has been known to compress, slite stretch helps.
Swap a coil pack and see if the other plug start giving you problems, if it does you need a new coil.

 

[etipp98]

Yeah, also check the gap of the plug, should be around .028.

 

[bspeed3]

Alrighty, heres what I've done so far:

I've now switched the coils but the problem seems to be the same. At the advice of a coworker who's built a ton of cars and used to work with formula junior, I bought some injector cleaner, and have run some of that through the car - still no change.

I'm close to running out of options for what I'm going to do. Today I'll replace the remaining three spark plugs, for consistency and to check all of the connections one more time. After all last time I changed the 1 cylinders spark plug it fixed the problem for 5 or 10 miles.


If that doesn't work someone had suggested my problem may be the valve gaskets? Does this seem logical to anyone? I get the impression at that point I probably won't be able to fix the problem myself, and I gotta take it to a shop. Anyone else got any last ditch suggestions?

Thanks for the help everyone,

Bspeed3

 

[bspeed3]

So thanks for the help everyone. Turned out to be sum crummy gas I got in NJ - idiot at the pump probably took a wizz in my tank. Got some fresh 93 here and she's running great again.