Engine Misses and Cuts Out On Freeway

engine missI 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?

Hello there

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.

Please share this with your friends,

Austin Davis

Posted in: Running Problems

2 Comments on "Engine Misses and Cuts Out On Freeway"

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  1. T. Park says:

    The 1997 Suzuki Sidekick with 277,000 miles on it has problems with the automatic transmission. For several years, it has had problems reversing in that it was slow and would sometimes jerk backwards suddenly.
    Just last Saturday, it was running fine until I parked in a slightly declined parking spot and tried to reverse. It couldn’t reverse even with high RPM, so I switched to my 4-wheel drive and it did the trick. However, after reversing, the car had problems moving forwards. Turning off and on the engine every mile would give me that normal forward movement, but it would eventually rev up and still move little or nowhere at all. A burning transmission fluid smell began to permeate the vehicle and by the time I got home it was smoking black carbon from underneath the vehicle.
    Upon checking the transmission fluid, it was half full, but black and watery. I filled it with half a bottle of Dextron 3 and that allowed me to drive slowly to the Lube place. After flushing and replacement, it was still revving up and moving slowly on the highways anytime I was approaching 40-45 mph. Moreover, the car would be slow to move and even jerk forwards after leaving a stop sign or light.
    Is this a transmission problem, a linkage problem, or a spark plug problem (i.e. haven’t had a tune-up in years)?

    • By Austin Davis says:

      From what you have told me I would suspect that the transmission has finally played it’s last hand and will need an overhaul. This will be an expensive repair, and personally I would think real hard before I put that kind of money in this vehicle…unless you are really in love with it and know the rest of the vehicle is in sound mechanical condition.

      You might be able to find a used transmission at a junk yard, but this would be a gamble and a short term fix to sell it…but even this route is going to be pretty costly and you might not get your money back once you sell.

      It is sometimes better (although not an easy decision) to cut your losses and trade in to a newer model than to keep throwing money into costly repairs that never seem to end.

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