99 Ram 1500 5.8L 80K miles. There is a shudder that started when in overdrive 40+ mph and I gently accelerate at the point where it prepares to shift out of overdrive. Disappears if I downshift or if it auto downshifts or if I ease off throttle. Any ideas?
So far: new plugs, plug wires, checked fuel pressure, checked compression, transmission fluid changed 3 times and once since shudder, tried fuel additives, changed coil, checked u-joints, and does not appear to be pre-ignition (have had a ping since new at the same point - cured by injector cleaner on a regular basis - dealer could not fix).
Could it be carbon buildup in cylinders?
I have the same problem with a 1996 Achieva. Word for word. I started with the fuel filter and it made a difference. Not perfect, but the plugs and wires are next and I hope that the combination will do the trick.
Did you find a solution? I too have the exact same problem…it’s most noticeable when I’m in cruise control, not when I’m using the accelerator. The local shop I took the truck to (I’m new in the area) said that it may be carbon build-up and that long sustained driving would likely help. The manager also acknowledged that adding some cleaner would be beneficial. He even dangled the complete fuel system cleaning for a mere $149. I sent this post to him for his consideration, but would like to know if you’ve found any additional useful information.
It’s sounds like the clutch in the lock-up torque converter is shuddering.
LubeGard has come out with a product called Shudder Stop. This added to the tranny fluid to stop clutch shudder.
You might want to give this a try.
Tester
I supposed there isn’t any check engine lights (or, symbols)? The fuel pressure should be checked (after clean fuel filter installation) with the transmission in Drive, and the engine at 2,000 rpm. This simulates the speed, and load on the engine, that the shudder (possibly misfire) occurred. The fuel pressure should hold, within permitted values, for the duration of the two to three minuet run.