After Trans oil Change/harsh downshift now
 

On my 2002 4.4 with 125k I had the trans oil changed and filter changed.

OEM fluid and filter. The old fluid was black.

I now have harsh downshift...also if I tap the gas it slightly bangs....none of this is extreme but now its there and it wasn't before the oil change.

I was wondering if anyone else had this problem. Any ideas maybe add something to the oil?

Thanks

How much fluid came out and how much was put back in? How did they change it? If you did a power flush it is very possible that the trans is shocked and that is not good. You want to keep fluid change in a trans to under 50% if possible.

They put as much in as came out. They dropped the pan, changed the filter. No flush, not sure if the torque converter drains or not.

I could not believe how dirty the fluid was. It was black.

Clean the transmission TCM and gear selector switch cables.

A dirty pin (and there are about 25), will give you the exact symptoms. I had this problem twice.

you need to do a transmission pressure re-learn to the computer. i haven't done it before but that's what I read from other threads here.

Can you get a little more detailed please. The TCM is the same as the neutral safety switch? Does it unbolt or how to you clean it?

Thanks, I'll see what I can fin out.

This is always my fear when considering a transmission fluid/filter change. Some have no issues and some have issues after the change. From reading and researching, I can not get a clear understanding on the adaptation resets for a simple oil and filter change.

I would love to hear more theories on what should actually be done when changing the oil/filter in both ZF and GM automatic gearboxes and also the recurring conversations of leaving high mileage transmission alone vs. diving in and rolling the dice.

One guy I would love to hear from the is automatic gearbox guru over in the UK (I always forget his name) but he knows his stuff. (RRPhil)?

I hear you....My 02 4.4 is in perfect shape and I fixed all the engine issues, timing chain guides, valley pan and 3 new sets of front ends...while I can buy a brand new one I feel committed :) So I keep this as a beater but with all my cars and bikes I want them perfect. 18 year old trans fluid was black. I do drive this a lot.

I found this procedure and will try and do this tomorrow.

"Turn key to position 2. But dont start the engine.
-Floor the gas pedal for 30-40 secs.
-Release the gas pedal, step on brake and start the engine.
-Drive FORWARD (Not reverse, so make sure you are out of your garage before you attempt to do the transmission reset) "

Do this every other month or when the transmission start slamming again.

From my reading and research, I read that procedure you listed and some described hearing the clutches reset, others on our forum here said it did nothing, no sound or no difference. BMW Logic7 seems to be the reference for your ZF box and they claim the throttle pedal--> transmission adaptations reset procedure is only an old wives tale.

Everything about your ZF 6HP26, 6HP19, 6HP28 transmission issues | BMW LOGIC7

I did find this video for the ZF gearbox and a chart listing the adaptations reset procedure but honestly, I am no expert and am hoping to learn more from this thread.

https://www.youtube.com/watch?v=nN78ukXXF_o


https://blog.fcpeuro.com/hs-fs/hubfs...name=chart.png