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Right on the money (more) (archive)

[ Follow Ups ] [ 5-series (E34) Message Board ] [ Msg. Board FAQ ]

Posted by Kirt Koeller on August 28, 2001 at 14:16:19:

In Reply to: Re: so what was the diagnosis? posted by Will on August 28, 2001 at 12:33:01:

The trans can tell grade by looking at the throttle opening and output speed and if it sees more throttle and little or no change in output speed, out goes converter untill a change in throttle or output speed. Hope this makes sense.

If I got this right: the computer will sometime unlock the converter when going up a grade and result in a few hundred rpm increase in engine speed, so mine may just be operating normally. Converter clutch is fairly robust. More likely failure mode for the 4HP22 is the forward clutch, especially if someone revs the engine in neutral. Fluid will slip past a seal and apply the forward clutch, burning it out. Watch the fluid color: red to reddish brown is OK (mine's been red to red/brown all along - WD). If it gets dark, or if I start seeing 400-600rpm increases starting up a gradual incline then suspect trouble. Also be aware of it hunting in and out of lockup while traveling on level ground. Aside from the forward clutch slipping when you move off in 1st or 2nd, electrical gremlins should be checked before suspecting it's overhaul time. {Kirt: how well did I pay attention?}
WD

If you are from Auto Sports Unlimited, then yes. I posted this before I spoke to you, and since speaking with you am much more at ease with the tranny and what to look for. I was planning on coming back here and telling everyone what great advice you offered! I'm in Flint, so it's a bit of a hike to your place, but if it does give me trouble I'll be headed west. Thanks again,
Will

1990 535i with ZF 4HP22 automatic; 109,000 miles. Noticed this morning that the converter lockup is kind of soft; it is engaging but seems like not 100%. Used to be more firm, like a 5th shift. Had car in 'E' mode, then 'Sport' for a few miles, then switched back to 'E' when entering highway on-ramp. Mobil-1 synthetic fluid level is OK, fluid changed 7,000 miles ago and also 200 miles ago (just a drain & fill). Filter changed at 88k. My commute is 40 miles each way at ~77mph; usually runs 2,900 rpm, today ran most of the time at 2,900 but up some gradual slopes noticed rpms climb to ~3,000 to 3,100. I fear the converter clutch is slipping or is this normal? Suggestions? Any relays or fuses to check.






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