451 Transmission Issue: Slipping out of gear, shifts only at high revs, but better when warmed up

[tranced]

Hi all,

I've been lurking on these forums for quite a while now and have had a lot of success treating various issues on my smart up until this point.

As the title says, my '08 Passion 451 has had a transmission issue which has only become exceedingly apparent until recently - meaning it may have been a progressive failure somewhere. Its just hit 69k miles. The transmission has had the current issue for at least 1k miles.

 

The issue is when shifting. After a cold start and in manual shift mode, the smart will not shift out of first gear unless the car is at decent speed and the revs are high (i'd say above 4k, i don't have the tach. pods to tell)

In auto shift mode, the car will shift at normal RPMs but then--as the accelerator is depressed--the tranny seems to "slip" out of a low revving second gear and into neutral. When this happens the dash reads 1st gear and the motor is free-revving. I recover from this "slip" into neutral by releasing the accelerator and letting the revs reduce. Then I reapply the gas and will hear the clutch slowly grab/slip until back into a high revving first gear.

To get into second from then, I must push the gas a bit harder and shift. It seems to require a strong inertia to catch second gear.

 

Once the car has warmed up after about a half mile of driving, it will then shift from first to second at a more reasonable rev (2~3k).

If it has been 50 degrees or more outside, the smart will also show less problematic shifting at cold start.

 

The smart has had its clutch actuator replaced and subsequently configured at a mercedes dealership.

I have since adjusted it/moved it away from driver side so that the plunger is closer to the clutch plate.

I have also recently replaced the tranny fluid with the correct royal purple fluid -- this helped the smoothness but not the shift issue itself (PS: change your tranny fluid! mine was filthy).

 

I suspect a worn clutch plate, as I can feel it slipping during certain slow take-offs. Many times the upshifts will be harsh as well.

An OBD code of P0716 for Input / Turbine speed sensor A circuit range/performance is present.

 

My question is if the problem may be limited to a clutch plate replacement, or if the flywheel has become glazed, or perhaps it is even just an issue of some solenoid inside the tranny housing? I have replaced the transmission speed sensor (the one above the clutch actuator) but the code is persistent. I have also replaced the crankshaft position sensor (which may have nothing to do with the issue).