I have a 1990 M/B 190E 2.6 Automatic. Calif. Car family owned 120k miles all factory services done. I inherited this car from my parents it is a nice clean car.

Since I began driving it I noticed that it was having a increasing abrupt and harsh 1-2 shift at 3/4 throttle, to the point of chirping the tires, all other shifting seemed firm with no WOT shift flaring. it did have sluggish down shifting, and you had to give it at least 9/10 throttle to get it to go from 2nd to 1st when accelerating from a stop or 4th to 3rd when getting on the freeway.
I put a Mity vac. on the vacuum modulator hose at the intake runner for cly.6 and the vacuum modulator held vacuum with no loss. I did however notice that it was slowly starting to lose trans fluid with no external leaks. so I installed a FEBI NR 01917 vac. Modulator [red]that replaces the M/B 126 270 25 79 [red]modulator that was on the vehicle, and while the modulator was out I inspected the modulator pin and it appeared to be fine.

While I had the vehicle in the air, I changed the trans fluid[dexron3/mercon] and filter with a aftermarket[febi/meyle?] filter I have no way to check trans pressures, so I decided that seat of the pants would work. I also adjusted some of the slack from the kickdown cable. kick down performance seems real good, however the up shifting is very soft. Throttle switch operation is good, Lambda adjustment is on the money, the engine runs great, transmission however seems to shift very mushy and now it has a 9/10 throttle flare when cold going into 4th.

My thoughts are that maybe I broke the modulator pin during reassembly, if so what would the symptoms be? or that somehow I installed the trans filter incorrectly and it is sucking air at times during hard acceleration. When I had the pan off there was no debris in the pan and the old fluid was still red and did not smell burn't.

Now the problem I have is soft, sluggish shifting at 3/4 throttle or more with a cold flare issue from 3rd to fouth at near WOT [when cold] no more tire chirping no more firm shifts and adjusting the modulator pin 5 complete turns clockwise made no difference in shift quality at all, disconnecting the vacuum line to the modulator makes no difference in shift quality either, still soft and somewhat sluggish. trans fluid level is exactly on the full line when hot and about 3/4 inch below the cold line when cold on a level surface.

Anyone run into this situation before? any ideas? I do not have a pressure gauge,so I have no way of checking pressures, but it would seem to me that I should be able to adjust the modulator and actually feel some difference if shift harshness and disconnecting the vacuum line should result in very harsh shifting. Could my adjustment of the kickdown cable caused this issue, kick down performance seems very good now, before it would not kickdown with out engageing the kick down switch. I put some more slack in the kickdown cable,with no improvement in shift firmness.
I have just about run out of clockwise adjustment on the modulator. Any Ideas??

Go for a search for K1, K2 spring kit up date...hope it help

make sure the vacuum hose is on shift selector its hard to see because it on the top of the transmission ....if the hose falls off it make the shift really hard and uneven

There is another vacuum hose to the transmission on my 190E 2.6 Gasoline motor? or are you talking about the vacuum hose that goes to the vacuum modulator on the left side of my 190E transmission, this is not a diesel engine.

Is not the shift selector the control lever inside the car [PRND32] that you use to go from park to drive etc.???

Do you have any real good links to the Superior or Factory M/B K1,K2 springs and the installation instructions? I spent hours out here looking and only found information pertaining to early 1980's 190's and no real clear instruction on how to install the Superior K1.K2 springs. My 190E is a 1990 2.6 Gasoline motor.