I was driving and all of a sudden the car started to shake violently.

QUESTION: 1997 Nissan, I was driving and all of a sudden the car started to shake violently.The car started to reduce speed to about 20mph even though my foot was on the accelerator the car would not go over 2000 rpm's and would not go over 20mph. I have visually inspected the timing belt and there seems to be no rip or tears on it. I tried to add oil just in case the car was running low on oil. ANSWER: If your car has a timing belt, it is enclosed within the timing covers and you would not be able to see it. Most Nissan's have timing chains, so I don't think you saw the belt. Being said, I don't think you have a timing issue. I think you have a misfire on one or more cylinders giving this reduced power and violent shaking. If a check engine light has come on, you have to find out what codes are in memory. That is the first step. That will lead us to the offending cylinder if this is due to a misfire. Once we find the bad cylinder, we have to confirm, spark, fuel and fuel injector pulse, along with compression. One of these things is missing causing the misfire.