hello,
Can you tell where I can adjust the vacuum pressure going to the tranning modulator. I was told it maybe to high,and reason for late shifting in 3rd&4th gear.
I have a 88 190e 2.3

The Bowden cable is what determines the shift points. Adjustment is at the throttle linkage near where the accelerator cable attaches. Do a search for more info.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

I was told that too much vacuum pressure could cause the 3rd&4th shift problem,is there any way to adjust the pressure before it reaches the tranning modulator/

No, it cannot be adjusted. The modulator adjustment affects whether shifts are hard or soft, the Bowden cable adjusts the throttle points at which shifts occur. Adjusting this will somewhat affect shift harshness too. Engine torque close in both gears being shifted = smoothest. Also, vacuum 'pressure' will vary with engine speed and throttle opening, so shift points will also affect the vacuum the modulator sees.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

ok,is there a way to to adjust the engines flow of pressure when throttled at an higher rpm so that the modulator will not see so much?

Does the modulator affect the smoothness or harshness of all of the shifts at once or are there separate settings for each shift. The reason I am asking this is my 1993 300E 3.2 shifts smoothly except for the 3-4 shift, especially when cold. There is a definite "thunk" on this shift. Seems less pronounced during fast acceleration.

The point of the adjustments of the modulator and Bowden cable is to calibrate the shifting characteristics of the car. There are no other adjustments for this on this car. If you are asking whether there is some aftermarket device to modulate vacuum, I doubt if there is anything useful in this application.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

If your car is upshifting at too high a speed, but shift harshness is OK, LENGTHEN the bowden cable going to the tranny a little. The Vacuum modulator on the tranny works inversely--the more engine load (lower vacuum) the higher the shifting pressure (firmer shifts) and the higher the speed at which the tranny will upshift. Adjust the Bowden Cable to change the light throttle shifting speeds. LENGTHEN if to LOWER the shift speed.

Adjust the vacuum modulator to regulate the line pressure (which controls shifting firmness) ONLY if you know what you are doing--you can cuse problems by messing up the line pressure adjustment with the vacuum modulator adjustment.

Just throwing this in for your information http://www.continentalimports.com/ser_ic20242.html

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1986 560SL
2002 Toyota Camry
1993 Lexus