After Trans oil Change/harsh downshift now

[andrewwynn]

@ rockit: do you have a scanner that will show you realtime solinoid pressures? With the 4.4 it's not uncommon to develop a hard downshift from 2-1 from seal wear and usually is fixed with seal replacement from my understanding.

With the relatively not terrible prices of the solinoids, often people will choose to hear replace the solinoids with the seals. (I was planning to do that when my transmission started to slam shift before I discovered the dirty connector actually causing the problem)

[wpoll]

FWIW, the trans reset procedure mentioned about (press the gas pedal for 30 secs etc.) is complete crap.

The reason it persists on the internet is that it DOES actually do something - it forces the transmission into sport mode - and that does feel different to drive, so the owner thinks they have reset something. But once you turn off the key - game over. The trans reverts to normal mode and you have done nothing. But by then you are convince did something and you don't notice the next trip is back to the way it was...

The same sort of myths exists in motorcycling circles, for resetting ECU and throttle adaptations etc. It's all hogwash....

[Redraptor141]

When I did my 535d E61 5 series (6hp28/32) the procedure from BMW/ZF was to do the oil change as per instruction and then perform the Oil Change Adaptation reset NOT the clutch wear adaptations.

So the oil wear is as the trans oil breaks down the clutch friction material will cause the oil viscosity to increase and the trans will adapt to this slowly over time. So the trans pressures required to clamp the clutches is differnt.

Once you change that fluid to nice clean new stuff the computer still thinks that it’s the old thick stuff, and the clutch application pressure it apples will be the same. So you get hard changes. Resetting the oil adaptations values means the trans is set to a datum as “just off the line” aka new oil. I’d start with the oil adaptation reset and see how it goes.

But equally ZF 1/2 soleinoids are notorious for going and are really easy to change. I’m sure when you do you can but I’m the new “E” style soleinoids...... but you would have to research that!

Only problem with that is the sump need to come back off to get to the back of the mechatronics unit. Plus if your there you might as well get someone to open the mecatronics and give it a good clean out. Only takes a bit of grit in a fluid way to change the pressure flow and therefore effect gear change characteristics.

[Redraptor141]

Oh and plus one for the throttle pedal reset. It’s rubbish. At most you reset the TPS adaptations

[andrewwynn]

Originally Posted by Redraptor141

Oh and plus one for the throttle pedal reset. It’s rubbish. At most you reset the TPS adaptations

Correct will not do anything to the transmission, but will recalibrate the throttle position sensors.


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[wpoll]

Originally Posted by andrewwynn

Correct will not do anything to the transmission, but will recalibrate the throttle position sensors.


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Not even that - I'm pretty certain the TPS is baselined each time the key is turned on (when the DME is booted). I don't think anything about the TPS position is stored from one igntion cycle to the next.

[Redraptor141]

BMW should have just not put a bloody “lifetime” sticker on it and just do an oil change every 70,000 miles life ZF reccommed!

[upallnight]

Originally Posted by Redraptor141

BMW should have just not put a bloody “lifetime” sticker on it and just do an oil change every 70,000 miles life ZF recommends!

Most new owners that buys or lease a BMW brand new will not keep the car beyond 60,000 miles. BMW offers their free maintenance program with a new car so if they don't have to include the ATF replacement it's just more money to BMW. Now I'm saying most, I know there are a few owners that bought their BMW brand new and are still driving it.

[andrewwynn]

Incorrect. I once reset adaptation on a buddy’s x5 and it ran like absolute shit until he did the TPS reset. There is something wonky with his x5 from having a replacement engine but twice when his adaptations were reset the car ran like absolute crap until the method describe above was performed.

[yes_its_neil]

How about in sport mode, any difference? I can't offer any advice, but it may assist in isolating the fault if there is a change in shifting. Obviously not relevant when shifting to or from reverse.