Just recently bought a used 44,500 mile c5 (ls1). I only had about 350-400 miles on it and took off on a cross country trip from Idaho to Virginia. Currently in Indianapolis and I am going to wait here for a day due to the recent winter storm in West Virginia. The car was running smoothly and had zero problems until around halfway to Indiana. After I got to my hotel today I decided on a Walmart trip and noticed that it was getting even more rough with a raspy sound starting to develope.

After some quick Internet research a lot of sources are saying to replace the spark plugs and wires before I do anything else. Does this sound right?

The cars oil pressure, temp, and engine oil life are all good. No check engine light or warnings from the car's dashboard. I don't hear or feel a problem in higher gears with highway speed. Most noticeable at idle and slow acceleration especially if I stretch the gears out a bit.

Should I take it to a dealership and have a full inspection? Replace the plugs somewhere like jiffy lube (temporarily) so i can see if that cures it for the rest of the trip? My issue right now is I'm stuck with a full days drive before I reach my destination.

 

You might first want to check for any codes. It can be done on your DIC. Get back to us and report the codes if any. List if the code has
a H or a C. (history vs. current) On trips, you could of got a bad tank of gas or something simple.

 

I checked this morning, no current codes. Could this simply be the difference of a mile of altitude and possibly bad fuel? What octane and brand fuel do you guys recommend?

Should I still get the plugs changed out today?

 

Tough question.....don't know how bad your problem is. A dealership
(stealership) can and will run up a bill to a major number. What I am saying....I don't know how driveable your vette is or isn't. If this problem is minor, you might want to run a can of "SeaFoam" or
"chevron concentrate" thru it if its gas related. If it is a bigger problem,
and in the middle of a trip, I guess the dealership option is your choice.
Good luck.

 

The car is still very much drivable. But I was just really surprised as to how it was suddenly a problem. I'm a big fan of fixing things before they blow up haha.