Wierd engine/transmission behavior

[Bo525i]

I´ve got this odd behavior, the engine starts to stumble @ 2000-2200 rpm - 110 Kph/70 mph,looses power for 15 secs and the autotrans enters 4th soon after, revs up to approx. 3000 for 5-10 secs, picks up speed, then enters 5th and returns to driving normally again.. It seems to occur mostly when the weather is damp or its raining!

fuelpump,filter,sparkplugs etc. are relatively new

Am I running on too little trans oil or do you guys have some other suggestions?

[whiskychaser]

I imagine you dont keep your right foot exactly where it is while that goes on. So as soon as you move it the problem goes away? If so I'm thinking throttle position sensor - both engine and tranny need a signal from it. Worth a check with an analogue meter?

[Bo525i]

That does make sense, there have been times where I´ve noticed a change when I wiggle my right foot some..

Thanks, I´ll be checking that for sure!

[Bo525i]

I got hold of a "newer" used throttle valve switch (13 63 1 726 591) and switched it with the old one.. I haven´t thoroughly tested it yet but from the first drive at speeds/rpms that normally produce the stumbling it would seem that it helped, only further testing will tell really!

I didn´t mess with the secondary ASC+T throttle valve switch as I haven´t had any probs with it so far..

[BigKriss]

I would look at / replace the trans fluid if that hasn't been done recently but it might be pain if you have a "sealed" transmission.