4HP22 Tranny problem...you out there Kurt???

[Robert K]

I have a 1991 535i that I've kept in great condition for the last six years I've owned it. Regular maintenance on everything. Most people literally think it's only a couple of years old. Anyway, every so often, the auto tranny decides to start making a sort of banging noise as it downshifts into first gear when coming to a stop. All other times, the tranny shifts fine, smoothly and easily going up and down the gears. But then, all of the sudden, it will just start banging that one downshift. Personally, I think it's an electronics glitch, since it can come and go and the tranny always works fine most of the time. I'd love to identify the problem and fix it, but need a bit of help since I am definitely not an auto tranny expert. Can anyone out there offer any advice about this problem?

Grace and peace,

Robert K
1991 535i

[Jon M.]

I have a 1991 535i that I've kept in great condition for the last six years I've owned it. Regular maintenance on everything. Most people literally think it's only a couple of years old. Anyway, every so often, the auto tranny decides to start making a sort of banging noise as it downshifts into first gear when coming to a stop. All other times, the tranny shifts fine, smoothly and easily going up and down the gears. But then, all of the sudden, it will just start banging that one downshift. Personally, I think it's an electronics glitch, since it can come and go and the tranny always works fine most of the time. I'd love to identify the problem and fix it, but need a bit of help since I am definitely not an auto tranny expert. Can anyone out there offer any advice about this problem?

Grace and peace,

Robert K
1991 535i

Robert - Replace your throttle position sensor. I had the same problem in my '92 535ia and Kirt pointed me in that direction. It's something like $60-75 bucks from BMA and a very easy swap.

If it's the TPS, it's sending faulty signals to the tranny computer. It could be other problems, like speed sensor etc., but start there - the symptoms are exactly like mine.

[George M]

before replacing the TPS, try adjusting it per Bentley. Other possible culprits...a slightly plugged valve body...sticky solenoid valve....and unlikely in your case Robert as I presume you know to change your fluid and filter on your trans...this can cause issues as well.
Good Luck...contact Kirt for the best resolution.
George