Acceleration thump

[2buicks]

Recently my 1997 Lesabre gives me a thump feedback when accelerating from low rpm (high gear) such as accessing the interstate or just accelerating from say 60 to 70 MPH. If I lightly accelerate, it will not thump, but if I want the speed now and come down on the gas pedal, it has a good chance of acting up. What do I mean by thump? It's almost like someone turning off the ignition. It gives off a very pronounced thump. Back off on the throttle and everything is normal. When I first bought the car 7 years ago, it would feel like a misfire doing the same acceleration. I have just learned to be patient with how I accelerate and it's been fine. Now it seems like the thump is happening more often and with lighter acceleration demands. Could this be something electrical such as coil packs? Plugs and wires were replaced when I bought the car. What symptoms do position sensors give? Car runs great around town so this is really frustrating. Any feedback would be appreciated.

[HotZ28]

Without codes, all we can do is speculate. You said the plugs & wires were replaced when you bought the car 7-yrs ago. How many miles has it been driven during this time? What is the total car mileage? You may have a bad ignition wire, coil or crank position sensor. Have you checked the transmission mount?

[2buicks]

Just turned 80,000 miles. I car pool to work, so I have only put 38,000 miles on the car in the 7 years I have had it. This car runs great around town, it only acts up when you put a load on it, such as accelerating on the interstate. Yes, I wish it would spin a code. No CEL and I am sure there are no codes without that coming on?

[maxwedge]

Sounds like typical plugs/ wires, but as mentioned a full scan may show something.

[2buicks]

Z AND MAX - I got to thinking about the plug replacement I did 7 years ago. I did replace the plugs, but only after replacing the #6 plug wire. All were not replaced as the misfire spun a code pointing me to #6. I just ordered a new set of plug wires so I should know if that works after I replace them not this weekend, but next. I am not going to replace the plugs again as they only have 38k on them. Thanks for all your feedback, I will reply back when I know if this helps. Thanks - Rick

[dpalomaki]

Is the "thump" like an engine stumble or misfire, and not a physical thing like a harsh shift or noise such as might come from a bad engine/tranny mount that gets stressed to the limit during acceleration?

[2buicks]

Thanks guys! I replaced the plug wires and all seems better. This weekend I put the car up on the ramps for an oil change and I did notice that the transmission mount on the passenger side behind and above the oil filter
appears to needing some attention. It looks like an over grown dog biscuit with rubber bushings on each end. The rear bushing is starting to bulge out of it's original seated position. Can these bushings be replaced or does the entire mount assembly have to be replaced? Thanks for your feedback!

[HotZ28]

ANCHOR Part # 2662 Price: $7.37 RockAuto Parts Catalog

[2buicks]

Z28 - That looks like the bad boy, thanks! The one I have is probably the original and it looks like it has aluminum body to it, but this will work. Question, is this in a neutral state and can it be replaced without having to support anything? I thought it was to support the transmission, but now that I see this, I saw a similar item on ebay and it was listed as an upper torque strut? Could it be that the transmission merely gives it a place of attachment? I don't know why they call it "upper," it appears lower, just over the oil filter. Thanks for your feedback.