backstory:
197,000 miles

Ive had the V for about 3 months, the trans fluid was very dirty when I got it. I flushed it 4 times and filled to spec. engine runs great and is strong. trans feels a bit worn and it does the "catch up" issue that ive felt in other high mileage automatics. Basically if you let off the gas and let it idle down as your driving, then get back on the throttle, it takes a second for the transmission to enguage again. might be a confusing explination but im hoping someone understands. No other drivability issues

the issue:
at partial throttle the car will start surging at a steady pace, ive had passengers ask me why im hitting the gas and then letting off. its almost as if the drive line is a big rubber band, thats the best way I can describe it. it goes back to normal if you open the throttle or let off the throttle. engine is not missing or sputtering. zero driveline noise. just a minor pulse or surge.
help me troubleshoot i dont know automatics very well

 

Any check engine lights? Does it happen only when constant speed or any time? Does your selector lights stay solid? What does your tachometer do when this happens? Need a lot better info.

 

no CEL

its mostly during partial throttle acceleration, it doesnt happen accelerating slow 10-15% throttle, and it doesnt happen over maybe 30% throttle, only 15-25% throttle roughly

gear selector light? normal

tach bounces with the surge, maybe 200-400 rpm fluctuation

 

Sounds like the torque converter lock-up is engaging and disengaging repeatedly. Put the gear selector in "D3" and see if it does the same thing. If so check it in the "2" position. Try to keep conditions the same as your problem areas with "D4". Report your findings.

 

what would it mean if it happens in d4 and not the other drive gears? im not very familiar with the operation of the torque converter.

I was under the impression it would only lock in overdrive

and its not a very abrupt surge, very minor if that makes a difference

 

hallp