Rough / Double down shift?

[simoncpw]

Hi all,

I recently noticed my X5 4.6iS 2002 has develop the following symptom:
1) cruising in D mode normally on highway, 80Km/h, need to take over a car, floor the gas pedel
2) car auto down-shift one gear (ie: 5th to 4th)
3) but shortly after less than 1 sec, the car will down-shift again (ie:4th to 3th) for a split second, then it up-shift.

So due to this "double down shift" from 5-4-3-4 gear, the car suddenly surge forward abruptly and the RPM goes up to 6-7000

On one occasion, the "Trans Safe Prog" showed up which prevented an gear change. And doing a reset to the adaptive transmission cleared it and gear change normally.

But problem comes back again the next day (without "Trans Safe Prog" so far).

Any suggestion on what this might be?

Thanks.

[TheKingSim0n]

What year and model is the X?

[simoncpw]

Sorry forgot to mentioned that it's a 2002 4.6iS. Info added to the original post now.

Thanks.

[Weasel]

Since the trans failsafe came on once there should be a memory code stored in the EGS os DSC... but you would need a GT1 to read it... Hopefully it is something simple like a sensor or something. Otherwise, while it is in GT1 diagnosis you could have the transmission and engine adaptations reset. Are any of the members that bought GT1s located anywhere near you?

[TheKingSim0n]

To be honest with you, with the year and the transmission (Z4) it sounds like your transmission is giving in. I really dont think its some sort of sensor but I honestly would not know 100% from what info I was given.

My transmission has been doing the same thing and it has alot of other issues, i have a 3rd party warranty which should cover it so I guess i got off lucky. Other wise in your case id first try replacing that 100% bullsh*t "lifetime" transmission oil. I assume you have a Z4 transmission which should take ESSO transmission fluid. do some research as I did about the history of your transmission and do some troubleshooting. Im sure you can find alot of posts and threads as I did when this first happened to me.

I wish you the best of luck!

[simoncpw]

Update:
- tried in S-Mode, the "double down shift" happens even more often!
- tried in manual mode, NO PROBLEM found. Gear changes at low or high RPM, up or down shift, all seemed pretty smooth. Definitely no sudden surge / jerk.
- after the above 30mins drive, it seems like when in D or S, the timing / gear chosen by the computer is off. Changing gear manual had no problem at all.

Hi Weasel - Unfortunately I don't know anyone around with a GT1. But I did plug in my PEAKE code reader, and no codes found. Would the "30 second reset" resets the codes error codes too? And if changing gear in manual mode had no problem at all, is it safe to say that the core of the transmission should be ok (ie: not an expensive fix!)?

Hi Simon - Thanks for your advise. That's what I'm worrying (transmission giving in), but just want to do a little research first before I bring the car in for a check. I did change the transmission oil only a few weeks ago.

[TheKingSim0n]

You recently did a transmission oil change? You did this oil change due to the recent shifting issues or just because you felt it was time to change that "Lifetime" oil ?

Because if you did it just to change the Oil then maybe the oil that was changed had some sort of effect on the transmission. The way I can tell that its not the transmissions computer is, put the car in manual and right away before you accelerate, put the manual on 5th gear. start driving real slow, if the computer changes it right away to 3rd gear then the computer is fine, its the transmission itself.

Ive seen X5s with bad computer transmissions and when they were on 5th gear manual they would either be stuck on 5th at a slow speed and not change or it will jump to 2nd or 1st gear in the manual mode. I believe the default gear it should jump to is 3rd? but i could be wrong. Anyways I dont think its the computer for other reasons, its an 02 and ive seen alot of buggy transmissions come from the 02 x5 4.4, to be honest i think the 01 has a better tranny then the 02. the 03 has alot of messed up transmissions two but for the 03 ive seen the most at past 150k....

Wish you the best of luck again man and let us all in on the updates

[simoncpw]

The oil change was suggested by the trustable & reputable local workshop that I always go to. In fact the oil was changed twice because the oil condition was pretty bad / black after the first change.

I'll try your suggestion to start at 5th gear. But what I meant was the computer was able to change gear, but it seemed to have picked the wrong gear / timing, especially when at high RPM. The "30 second reset" DID / WILL correct the problem, but it will come back again after a short while (of sporty-driving).

Anyway, I'll do the 5th start test and report back. Thanks.

[TheKingSim0n]

Wow black? you sure your talking about TRANSMISSION fluid? or engine fluid? because ive seen really burnt transmission fluid but it was never black..... :/

It smells really bad and has a funky look to it but not black. If it was black and your sure its transmission fluid were talking about then you really need to replace your transmission or at least go into a reallly good local transmission shop and ask them for a transmission tune up.

But make sure that the transmission shop is familiar with the X5 4.4i/4.6/4.8i's.... make sure they dont flush the transmission the wrong way or its a reallly annoying problem...

:/

I believe the 4.4 and 4.6 are Z4 transmissions which take ESSO only.

Here is a helpful chart to help you understand what I mean better, I dont have that good of a way to explain it via message board lol

[simoncpw]

May be not black (that's why I put "bad / black" ;-)) as I didn't see it myself. The guys are pretty good and have been able a couple of tricky problems for me so far.