1997 Q45 Check Engine Light

2 weeks ago the check engine light came on in our 1997 Q45t. A day before that, the car started to hesitate and stumble a little.

We took it in to Infiniti for service. They changed the #1 coil pack and all 8 spark plugs.

The service tech told us that we should replace all 8 coil packs, because once one fails the tend to fail in a domino fashion (one after another). Sadly, all 8 coils would have cost us over $2000!!

The car ran fine for about 5 days, now the Check Engine light is on again and the car is stumbling.

Questions:

1.) Is this a common problem, if so, what is the remedy?

2.) Is it probable that the coils will start to fail in a domino fashion (I've never heard of that)?

3.) How can I test the coils?

Any other suggestions are greatly appreciated.

Coils are difficult to test without a scope. Coil pack failures are rare. Never heard of the domino theory. Was this techinican an Infiniti senior technician trained on the FY33 (and hopefully G50 also in 1989)?

Might post in the Infiniti Mechanics Forum over at www.nicoclub.com .