Just brought home a 1992 300E from Texas. 56,000 verified miles with all the stamps in the service book. The car looks and feels new. Drove it home 2100 miles without a hitch except for a tranny that started to shift harder as the temperature dropped as I headed north.


Cold morning starts produce delayed and very abrupt shifts. This condition smooths out after warm up but there's still a pop in the shifts as compared with the silky smooth shifts while driving down south.


Trans fluid looks normal,the level is good and given the mileage I'm not suspecting mechanical wear. I've search the problem and am suffering info overload. Could the more experienced and technically advanced members please check my thinking on the problem.


1) Electronic warm up cycle induces long shift duration and in my case hard shifts. I understand it's function is to get the cat to operating temp as quickly as possible but it annoys the he11 out of me. Can I disable this feature by disconnecting the single pin connector at the tranny without damaging anything?


2)Before I try to fiddle with the modulator valve on the tranny I should first check the quality of the vacuum going to the valve. Do I disconnect the line just before the valve to test and what values are considered normal vacuum? What values do I look for under what conditions.

3) How do I test the modulator valve. What condition is considered faulty?


4) If proper values are found for the vacuum source and the modulator is good do I then attempt to adjust the modulator valve and, if so, how is this done?


Is this a sound plan of attack or am I over simplifying? Please help. Sorry for the long posting.