My car is 8 years old and has only 45,000 miles on it. It started stuttering a few months back. It would happen infrequently, maybe once every few miles or so, and was sometimes very subtle, but it made me nervous to drive.
I took my car to my long-time mechanic who usually does my 6-month oil change and regular maintenance. It didn't surprise me that he couldn't recreate the stuttering and therefore was unable to do any repair work. The only solution was to keep driving until the problem worsened and became diagnosable.
A few days later while on the Servco Kaimuki website looking for the price of a new car, I noticed that I could easily book an appointment to have my car serviced there. The soonest time they had was in 3 weeks, but it was so easy to schedule and with no other options, I booked it.
The Servco mechanic also couldn't reproduce the stuttering. But they did recommend a two-step "BG intake cleaning" and spark plug replacement to start.
That did the trick. My car is now running as smooth as silk (knock on wood).
My bill shows the use of a GDI Fuel Kit which I learned while researching is a "powerful treatment which introduces chemicals and cleaners to the right areas of your entire fuel system - dissolving and cleaning accumulated buildup."
The following info is from torque.com.
WHAT IS CARBON BUILDUP?
Carbon is a by-product of the combustion process, which happens as your engine burns fuel.
Think of your engine as a fireplace or barbecue pit. When you burn wood, the by-product is the soot or carbon that coats the sides.
The same is true for car engines. Carbon builds up in the cylinders, intake and exhaust valves.
HOW DO I PREVENT OR REDUCE CARBON BUILDUP?
Today’s petrol and engine oils are formulated with additives to help keep carbon buildup in check. Ensure that you use quality fuels and change your oil according to the manufacturer’s recommendation.
A good engine oil is formulated with a degree of detergency to clean up these deposits. The carbon deposits will then be pulled away from the metal parts and trapped in the oil filter.
This underscores the importance of changing your oil and filter regularly!
HOW CAN I TELL IF MY ENGINE IS CHOKED UP?
If carbon buildup is bad enough, a few symptoms will appear. Rough engine idling is one sign. Poor acceleration would be another.
If your hear knocking/pinging, that could signify very bad levels of carbon buildup.