c6 trans issues

[89ford350]

hey guys new to this forum, just bought a f350 idi and having some issues with the trans. when i put it in drive, it only wants to stay in first gear. but when i manually shift it starting in 1st and shifting to 2nd its fine, and then when i shift it back into drive it just revs like its in neutral or something. cant seem to figure out what the problem is, i changed the vacuum modulater fluid and filter but still same result any help would be much appreciated

 

[franklin2]

How much foreign stuff was in the pan when you changed the filter? Fine particles are ok, but large chunks would not be good.

I am not sure what the neutral in drive thing is, but you do know there is a gizmo on the throttle at the pump that controls the vacuum to the modulator? It takes the vacuum from the vacuum pump and varies the vacuum signal to the modulator according to throttle position.

 

[89ford350]

fluid was pretty dark, not so much large stuff just fine

and your talking about that vrv thing on the side of the injection pump?

 

[USNENFTS]

So, on your fuel injection pump, there is vacuum throttle type thing (I dunno what its called). Anyway, it shifts your transmission based on where your throttle is at by changing the level of vacuum to the transmission, there is 2 or 3 bolts on this thing and if your looking at your engine, it on the right side of the pump. If you loosen all the bolts you will find that it can be adjusted away from you or towards you. Well, mine was not adjusted correctly and wouldn't shift out of 2nd..... So, what I did was get the tool I need to loosen/tighten the bolts, and go drive it and adjust it until I had it where I wanted it. Hope this helps!

By the way, there is always a solution to C6 problems, rip it out and install a ZF 5 Speed