I'm going to list three symptoms that developed very suddenly and seemingly coincidentally last week. Anybody got any ideas?

A: When you downshift it from D to 3, at road speed, with your foot off the accelerator, standard behavior is for the transmission to downshift and the rpms to jump up fairly abruptly to match the new engine speed for the lower gear at that speed. Instead, mine sort of seems to... freewheel. It doesn't return to idle, it's more like somebody pressed down a clutch pedal inside there and then just kept holding the RPMS right where they were for 4th gear. If I use my toe to accelerate the RPMs manually, as soon as I accelerate up as high as 3rd gear requires, things seem to lock back together normally, and then the rpms stay with the gear and road speed as they should.

B: Imagine going through a drive-through window. You're stopped, it's time to pull up one or two car lengths, so you press gently on the accelerator and then take your foot right back off. Normal behavior: the engine returns to idle fairly quickly since you didn't have much speed up and then you coast to a stop. What it does now: it's as if the transmission is driving the engine instead of the engine driving the transmission. It keeps moving forward under its own power very gradually slowing down until you have to help it with the brakes. As if instead of the engine keeping the back wheels moving at a certain speed, the momentum of the drivetrain is keeping the engine up to speed for a while instead until the momentum is lost.

C: Here's the really weird one. With the transmission in Park, if you rev the engine any amount (high or just up to 2k) it returns to idle more slowly than normal. Instead of sort of dropping like a rock to idle like it usually does, it takes an extra second or second and a half about doing it.

Transmission fluid is filled to an appropriate level and is reasonably clean.

The only thing I've changed on the car between not having this problem and having it is the replacement of my third broken accelerator pedal. Now... IF the accelerator linkages were suddenly NOT returning back to idle but instead just a millimeter or two off idle, it could potentially explain all of this. As I've posted in previous transmission threads, I have been able to reproduce Symptom A ever since we bought the car 55,000 miles ago by taking my foot off the accelerator, accelerating it perhaps a few millimeters, and then downshifting. That has ALWAYS produced that "freewheeling downshift" effect. However, normally taking my foot completely off the pedal and then shifting has resulted in an abrupt climb and re-interlock with the lower gear. This no longer happens.

I have checked the installation of the pedal and can't see that it's binding up anywhere, and i've tried sticking the toe of my shoe under the linkage and manually pulling upwards to be sure the pedal's returning to idle - the best I can tell it is.

Any ideas at all?

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL