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2004 Chevy Malibu - Transmission or spark plugs

I have a 2004 Chevy Malibu Maxx with a 3.5 L V6 engine. I bought it new ten years ago and it now has 71,000 miles. In the past year, I noticed that sometimes when I accelerated, the car hesitated for a split second. I assumed a transmission problem was around the corner. I recently had the car serviced and had the spark plugs and wires replaced. It is a 100,000 mile maintenance item but since the car was 10 years old, I decided to get it done. Ever since the plugs were replaced, the hesitation on acceleration problem has gone away. Is it possible that the problem was the spark plugs?

Sounds like it was either the plugs or the wires. Either of them on the fritz could cause the symptom. The plug gap will increase with miles driven. Maybe the gap had widened enough to make it out of spec. Did you notice any pinging? Pinging is a symptom of too wide of gap. I think more likely it was the wires. The insulation had probably cracked and you were getting some misfiring, the spark wasn’t all going to the spark plug, some of it was going from the wire to the engine case ground. Most noticed when stressing the engine, like during acceleration.

fyi, another common reason for hesitation during acceleration is egr problems.

It is quite possible that the problem was the plugs and/or wires. Despite the plugs being 100K mile items, the wires were 10yrs old. That’s plenty old enough - so I think your reasoning for having it done was perfectly sound. And if you’re only doing about 7K miles/yr does that mean there is a lot of short trip driving? If so you might find a shorter interval for spark plug replacement based on a “severe duty” schedule.

On the subject of the transmission, has that ever been serviced? I don’t think it ever had anything to do with the hesitation, but just bringing it up in case you want to minimize the possibility of future problems. The best thing to do is have the pan dropped and filter changed, and it’s best about every 30K regardless of what the manual says.

Cigroller - not that many short trips. The car sits a lot. I take the train to work and walk to the train. It is in a garage (unheated) and often goes a week without being driven. No transmission service. Just general maintenance inspections.

solved, must have been the issue, don’t be afraid to throw some techron or sea foam in there.

GeorgeSanJose - no pinging. No check engine light and I pass the Illinois emissions test - including my last one in December.