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Old 07-17-2016, 03:50 PM
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Join Date: Jul 2015
Location: South Asia
Posts: 311
300td shifting weird, diagnostic step confirmation

Going through some transmission stuff (only the SLS ... ughhh left to fix) and i wanted to make sure i was diagnosing this in the correct order.

The car shifts really abrupt (just harsh) and sometimes never quite gets into 4th unless i ease up on the gas and wait a bit for it to thunk in. I have tried doing the L, S, D method and in low 1-2 is a tad late... then into S 3rd is a little late, and then into D 4th will never come around unless i really ease it into 4th.

The transmission was replaced and torque converter reconditioned in 2012.

1. I checked the vacuum to the modulator and that is holding vacuum fine.

2. The only vacuum leak in the system i could find was in the door locks, so i plugged up the vacuum line going to the door lines in the engine bay with a golf tee.

3. The bowden cable... not really sure what to look for. It's resting in a position that seems to not have too much play and not too much strain on it. Kind of in a neutral spot.

vacuum pump is outputting around 22-25 on the gauge.

4. my last area to guess is the VCV valve. In and around the valve i see 3 things. I see the green hockey puck thing that goes in the top, a 3 way connector that goes into the middle and it seems right next to it there is a brown line with a blue line through it that goes into the firewall. I am not sure if this is where i should be looking for my problem... but this is kind of where i am honing in on.

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Old 07-17-2016, 08:04 PM
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Join Date: Mar 2008
Posts: 4,642
My Superior Shift Kit thread (W124 300DT)

great thread. see post 15 for instructions on adjusting the VCV.

What year is the vehicle? check out the vacuum amplifier if 84 and over (blue or black disk ufo thing with 4 ports on it)

make sure all linkages are operating properly and at proper lengths.
-IP should reach full throttle stop (this is the main concern)


TV / pressure control cable (bowden):

with engine running, the the cable should not be in tension until engine speed accelerates. This does not mean 'when engine speed increases'.

turn the accelerator linkage pivot on the firewall by hand with the engine running.

find the spot where rpms begin to take off as you hold the pivot steady.

at this point, the TV cable should be in tension, or just before rpms take off you should have 1mm of tension applied -maximum.

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