C4 slipping

[texasfairmont]

My C4 automatic trans is slipping going from 2nd to drive -are there any fixes for this or will I have to have a complete overhaul??

My shift modulator has to outlets, I blocked off one --would that cause this...?

[jessew]

Try changing the modulator and cleaning around the lines for it. If anything gets in there, it won't get the right amount of vacuum to shift on time.

[PaceFever79]

First try that ^ then adjust the bands and adjust the kick down cable (standard maintenance)

Has it been sitting for a long time? That can do in an old C4

The internal seals could be going bad, and or the clutches could be worn.

[texasfairmont]

going to buy a new modulator -check the lines -(question) where should the vacuum line be attached ? At the intake or on the vacuum tree ?

[jessew]

going to buy a new modulator -check the lines -(question) where should the vacuum line be attached ? At the intake or on the vacuum tree ?

I believe intake, not sure right off hand though.

[PaceFever79]

Yes it should have a direct path to manifold vacuum.

It can work on a tree but fluctuations in vacuum can cause erratic shifting.

If you have a direct manifold port use it for the modulator.