Stumbling/misfiring/check engine light!!!

[Bobiam]

My 2001 Boxster was stored for the winter and before I took it out of storage I put in a set of original type Beru spark plugs. The job went OK except that reconnecting the wiring harness to the coils was somewhat troublesome on several cylinders. This was the first plug change at 36K.

I drove the car over 3 days and it ran as good, or better, than ever. All mild driving. All of a sudden the engine started to shudder and the check engine light came on. After a quick roadside exam I was fairly convinced that I had a misfire condition as a result of one of the coil wiring connections slipping off. My logic says that this has something to do with my spark plug change. No damp or rainy weather involved.

The car will run at an idle but somewhat unsteady. It definitely stumbled and shuttered when accelerating but would cruise at 3000 rpm fairly well so I drove it the 3-4 miles home. No smoke of any kind. Once home I got under there and rechecked the wiring boots on the coils…….to my disappointment they were solidly in place.

Now I’m worried. I don’t have a OBD11 meter. I don’t know if an ordinary meter would tell me which cylinder was misfiring, so perhaps I need an expensive Porsche specific one to tell me that.

I can pull all of the coils and spark plugs and look for a problem, but unless the problem is visual, I don’t know how to diagnose it.

Any advice would be appreciated.

Thanks,
Bob


Ps Oh….and get this. While it was in storage, I bought a 3 yr extended warrantee WHICH HAS A 1000 MILE WAITING PERIOD. What I dope I was to be honest with them about the miles!!!