I have a Buick Century I just bought. When driving at cruise speed my car sputters after a half hour of driving, and gets worse when accelerating, more so than when decelerating, or at idle. I did not hear any strange noises such as popping from the engine or exhaust.
This symptom does make the car hesitate consistently at any consistent speed. I noticed that they did change the spark plug wires.
Can you please help me?
From your email, spark plug wires would have been my first guess. Spark plug wires tend to break down and fail more so when they are HOT and placed under a heavy load. The “load” is heavy acceleration…as would be pulling a trailer, climbing up hill etc.
The rubber on the spark plug wires becomes brittle, sometimes burnt by the hot engine parts, has small pin holes etc. and those defects allow the spark to jump out of the spark plug and ground itself to the metal on the engine.
Similar to a lightening strike on the Earth, the electricity has to ground itself to something…a tall tree, a building, airplane or a house
When the spark leaves the plug wire and comes in contact with the engine/metal it causes that cylinder (where that spark plug wire attaches to the spark plug) to miss-fire. A miss-fire basically means the cylinder is dead, there is no spark to ignite the gasoline, so nothing is taking place inside the cylinder.
If nothing is taking place inside the cylinder, your 6 cylinder engine is now a 5 cylinder engine. Lack of power, miss-fire, poor fuel economy and slow starts are some common symptoms of a dead cylinder.
For vehicles without spark plug wires (many newer cars do not have them anymore) the ignition coil is the culprit. The ignition coil sits on top of the spark plug and produces the spark..which then the spark plug ignites the fuel inside the cylinder.
Watch my video as I show a VERY shade tree mechanic diagnosis of spark plug wires
I would get the computer codes read and see if any information is being stored in your computer and go from there. I have seen a weak fuel pump cause symptoms of a misfire at cruising speeds, when you mash on the gas the pump works fine.
I have also seen the transmission torque converter cause similar problems. The torque converter is the heart of the transmission. A converter that goes bad, causes a “shutter” when in drive and under a load. So you are driving at 45 MPH in overdrive on a smooth street or going up a slight incline and you feel a vibration/shutter but it goes away once you give it a little more gas.
Try driving in DRIVE not overdrive, or LIGHTLY tapping the brake pedal (which releases the lock up torque converter) next time the problem happens. If the sputtering stops, you probably have an internal transmission problem.
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