Cadillac Repair: Bad exhaust smell from 98 Cadillac STS, spark plug wires, cadillac sts

Question
QUESTION: The STS has a Very Bad/Strong exhaust smell when the car is running. The smell also enters the interior of the car when driving. Can you explain what the problem is and what needs to be done to rectify the problem?
Thanks,
Dan

ANSWER: Has ANY work of ankind been performed on the vehicle prior to this smell ?.

Does it smell like gasoline or like rotten eggs ?.


what is the YEAR and MODEL of this vehicle ?.

---------- FOLLOW-UP ----------

QUESTION: The YEAR and MODEL is as I wrote in the subject matter: '98 Cadillac STS. After giving it more thought, since the smell of gasoline has changed over the years I have decided it smells more like gasoline, which is to say smells very bad. Also I notice the fuel level is dropping extremely quickly. My O2 Sensor is coming up as a service code as well as P300 although I don't feel any shimmy or sudden movement from the engine. Feels smooth. All this seems to say that at least one of the sensors is not operating correctly and is feeeding much more gasoline than oxygen. Also, one of my boots may not be firing corectly as well.
Do you concur?? Comments?

Answer
The FIRST thing you need to do is to make sure that all your spark plug wires are OK. A simple test is to wait until it is dark outside and using a spray style windex bottle with WATER in it, Start the car and spray the water on the whole length of all the spark plug wires and if you see any electrical arching from the spark plug wires, Replace ALL of them.  Once you get this resolved send an e-mail to: onlineautohelp@msn.com for additional assistance.