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Strange Sputtering while Pressing Gas Pedal

I have a 1996 Buick LeSabre with 110,000 miles on it. A couple times in the past, it had a problem with shaking when traveling at about 50-60 mph on the highway. The first time, my mechanic fixed some wiring, and the problem MOSTLY went away. Just a couple months ago, the engine was misfiring again and he switched the #1 and #6 spark plugs, said he did not detect a misfire after that, and again, the problem MOSTLY went away.



Well just over the weekend, I was driving for a few hours, and I started having more problems when pressing my pedal. If I push it in a little bit, it accelerates slowly but evenly, and, keeping it there, I can get up to around 60-70 mph. If I try to press harder on the pedal, the car shudders a little, doesn’t accelerate (in fact, it feels like it’s stalling a little), and the check engine light flashes. If I press down on the pedal quite a bit, it will accelerate more, but not immediately, and with substantial shuddering. It also shudders and shakes when it is just idling, and I have to find that sweet spot when pressing the pedal just a little bit in order to get my car to behave “normally.” Any ideas about what might be causing this? I have not yet talked to my usual mechanic about this problem, as it just started occurring.

Sounds like a weak ignition component.
You need to find a mechanic that can run tests in the ignition system, not just change parts.

I would also like to add that I was having occasional trouble getting my car started in the first second or two of turning the key a couple weeks ago. Anyone else have any ideas?

I think you haven’t gotten too many responses because you wrote a lot but didn’t end up saying very much.

Sputtering cars aren’t strange. Its often a pretty simple response to very basic kinds of maintenance issues. The thing is that you must not know this because otherwise you would have spent a little bit of time talking about feathering the gas pedal and a lot more time telling people about the last time your fuel filter was replaced, air filter, spark plugs and wires, whether the fuel pressure has been checked etc.; what your mechanic has actually done (other than “fix some wiring” - do you have any idea how much wiring a car has? or swap some plugs).

You also have a check engine light - those go with diagnostic codes. You need to find out what those were and report them. One or more will be for cylinder misfires (I have deduced from plug swapping and flashing engine light). But people would need the full list of codes (one of yours will be either P0301 or P0306 - but there will be more).

So, anyway - what you did was sort of like calling the doctor saying “Dr., it hurts, what do you think could be wrong?” So if you want some advice you’ll need to give the rundown - we now know the symptoms. What maintenance has been done and when? What diagnostic steps have been taken and results? What are the codes?

My 1992 LaBsabre was doing the same thing. I replaced the fuel pump and strainer (the old strainer was very, very dirty). The car is running well now. Replacing the fuel strainer may have fixed the problem alone but while you are in the you might as well replace the fuel pump.

Well, first, I’ve never heard of switching spark plugs, has anyone else ever done that? If I have a plug problem I put in a new set. Thankfully, today’s plugs last a lot longer. I would say that at 110,000 miles it’s time for a new set of plugs if they’ve never been changed. If it is electrical in nature it could be the plug wires or the coil. I usually haven’t had to change plug wires until about 150,000, but you do have a few years on yours. It could be a fuel feed problem. That would require checking the fuel filter and the fuel pressure.
My guess is at your year and miles you need a new set of plugs and a new fuel filter,