I had a spark plug break on me and it caused a misfire. I took it in and the mechanic replaced all spark plugs and wires. After getting the car back, I experience an occasional engine hiccup here and there. Took it back to the mechanic and told me that he cleaned off the valves of carbon build up. This did not alleviate the current symptoms. It is more noticeable while I am idling. It feels like a jolt. It appears to be worse after a cold start. I do not have a check engine light or do I notice the RPM needle go wild. What is the mechanic missing? What could still be wrong with the engine?
Vehicle is a 2001 Ford Windstar Sports SE, 6cyl, 3.8L,
I’d love to know how the mechanic “cleaned off the valves of carbon buildup.”
You need to report the vehicle’s mileage along with everything else about the maintenance history of the van. (E.g. is this the first time the plugs & wires were replaced? If so is your fuel filter just as old as your plugs & wires were? Etc.)
There are plenty of other things that can cause the problem. I don’t know the ignition system in this van for sure but somewhere there is a coil pack or coil/distributor that feeds spark to the wires. Each cylinder also need a reliable fuel supply (injectors and injector wiring). At the very least a basic check of the fuel pressure should be done. You could have an actual mechanical problem - a compression check would be a good idea.
When you turn the key to first start the car, does your check engine light come on then? (I.e. is the bulb/circuit actually working?) There can be codes even if the light isn’t on. Did your mechanic scan it? Perhaps now would be a good time to get it onto a scan tool for live data.
Vehicle has 137K. Bought it when it had 77K. First tuneup I have done to it. Fuel filter replaced six months ago and a fuel system service done three months ago.
Check Engine Light does come on when the vehicle is started. Does not turn on while driving. The vehicle has been scanned for codes and, according to the mechanic, no new ones have registered between the time the tuneup was done and the cleaning.
I brought up the coil pack and they assured me that it was fine. No leaking hoses were found. I’ll bring up the fuel/compression pressure check when I bring it back.
I am beginning to believe that the problem may very well lie with the parts that were replaced. I am going to ask that they check them again and make sure the plugs were gaped correctly and the wires do not have any cracks.
Thanks for the reply.
If I had an answer for you, I’d give you one. I was told that “they cleaned the carbon buildup by the valves due to the misfire.”
Update: After the replacement of the spark plugs, the vehicle went back to shop three times. I already told you what they did the first time. The second time, they decided to re-gap the plugs and re-do the fuel system service. They told me that they took it for a test drive and did not notice any abnormalities, but sure enough the jolt came back after I pick it up and a cold start. I took one of the mechanics for a ride, and he felt the same thing I did. The mechanic could not explain it and told me to drive it for a week to see if the problem will get worse or go away. Twenty-four hours later, my check engine light comes on. The third time I took it, they scanned it and found that Cylinder #3 was misfiring (finally an answer!). After some troubleshooting, they found that the “new” spark plug was defective. Now it runs fine.
Lesson: Do not believe every new part is in great condition.