'Jerky' acceleration 4.8is FIXED! (programming NOT tranny!)

[PropellerHead]

After I replaced my trouble-free 100k mile 2004 X5 3.0 last year with my dream X5 4.8is, I think I may have let the 11k miles, pretty blue exterior, and nearly untouched cherry interior cloud my judgement. I will admit that I was simply in denial about what a lot of people seem to think is the transmission shifting at funny points. Some call it 'hunting.' Like the tranny will shift up to second after a stop as normal. It'll head into 3rd shortly and then it happens...

Under fairly normal acceleration- (for me) in just regular old lopey down the road mode- not sport or Steptronic Manual- it would apparently shift down again for no good reason. It didn't do it ALL the time. Lord knows if I hammered the gas, you only had two things to do- Hang on and watch the gas gauge dive for empty. No funny shifting under full load.

But I don't drive like a maniac all the time. After almost exactly a year and 11K miles of trying like hell to modulate the throttle, I finally gave in and asked an old friend. Actually, I have about 10 years on him, but he's worked his way through the service ranks of a local BMW dealer. He's an old '02 and E30 guy as well. Good people.

On describing what was going on, I mentioned one of the things I'd tried in the last month or so to offset the issue: Turning to manual mode in Steptronic. But then, I noticed once recently that it did it again! Well now wait. HTF can it shift if the dang thing is IN third gear? Did the dash indicator lie? Did it just shift- under light acceleration/no redline without telling me? Not possible. This is actually a contributing factor as to why I was there. It was puzzling. It simply could not be transmission, I gathered. Could it be TPS? Could it be something in drive by wire? WTF?

Well, it turns out that my friend had experienced this same issue with another customer's car some years back. His was a 545. The two drive lines are pretty similar but some of the coding is different. Since he'd used the same method on many other N62's, this he thought would be the key to my solution.

Five mins later, he returned reporting an unusual setting found in the GT1/current BMW coding: Under Minimum Valve Lift, he reported that the setting on my 2004 X5 4.8is was 0.10mm. He called to a coworker to be sure, but neither had seen an N62 set this low. The correct setting is 0.30mm and not recommended above .8 for the X5. He doesn't know why.

He's changed this setting he said to address all kinds of N62 drive-ability issues- across the 5's, 7's, and the 6's, too. He said he's seen disappear the rough idle issues that some folks immediately say are guides (or something). The funny shifting or hunting of what looks like the transmission in a 5, 6, or 7 with this motor can also be affected by adjusting this setting.

I am happy to report that I noticed IMMEDIATELY the difference in drive-ability on my X5. It feels like a WHOLE different experience. It's no more crisp or faster or ANY of the crap that people like to say, but what it is now? Smoooth. Not as smooth as the 3.0 I had, but still.. VERY nice. Well worth the visit.

And, just in case anyone wants to head to a dealer and see if this solves the issue, I have a screen shot of the diag screen. Just for you guys! I hope it helps anyone seeing the same issues!

[Roadkill]

prop, i'm confused as to exactly what your issue was. i'm curious to know more about this "hunting" you've described. thanks.

[Icer006]

good stuff, propeller... the weird shifting in sport mode doesn't sound like valve body or tranny... at least one that i experienced.

[PUREVIL]

Very interesting. I'll be printing this and taking it with me next time I visit the dealership.

[PropellerHead]

Originally Posted by dinan e39

prop, i'm confused as to exactly what your issue was. i'm curious to know more about this "hunting" you've described. thanks.

well, it was weird. I described it as best I could above.

While accelerating, it really felt like the transmission shifts when it SHOULD just sort of ease into 4th gear. Maybe some demonstration with RPM and time in will help?

These are WAY estimates. It's difficult to even pay this close attention when the car gets into 3rd gear- I needed to look at the road!

Stop-Normal.
1st gear change- Not sure of RPM. Maybe 2K?- even if its not accurate, the gaps of about .5K are what it FEELS like anyway. Bear with the estimates.
2nd gear change-1.5K (I guess) to about 2.3K
3rd gear change-1.8K (closer guess) to about 2.4k

--and that's when it would happen--

The car would seem like it would downshift- back down to about 1.9K. And then it would quickly- like more quickly than a sedate, standard- NON SPORT MODE- acceleration and change through the gears should require-rev back to 2.4K or so...

4th gear change- about 2.6-3K. (maybe)

The rest of the changes and associated engine sounds progressed as normal.

The real clincher was the ONE time that it did it in manual mode. It was key to point somewhere other than the transmission after progressing through the testing. I tested what would happen if switching to sport mode from 'normal' for a few months, then finally just trying manual mode. When it did it there (only once), I knew something was amiss and I was more certain that it wasn't the transmission- Especially on an X5 with (now) only 22K miles that had behaved this way since 11K miles last year.

[SlickGT1]

Wow great info. I wish I knew this when I had the GT1 in my hands. I would have tried to figure this out. Is there any way you can ask him for instructions on how to get to that screen? Thanks.

[Roadkill]

Got it. thanks for the explanation.

Originally Posted by PropellerHead

well, it was weird. I described it as best I could above.

While accelerating, it really felt like the transmission shifts when it SHOULD just sort of ease into 4th gear. Maybe some demonstration with RPM and time in will help?

These are WAY estimates. It's difficult to even pay this close attention when the car gets into 3rd gear- I needed to look at the road!

Stop-Normal.
1st gear change- Not sure of RPM. Maybe 2K?- even if its not accurate, the gaps of about .5K are what it FEELS like anyway. Bear with the estimates.
2nd gear change-1.5K (I guess) to about 2.3K
3rd gear change-1.8K (closer guess) to about 2.4k

--and that's when it would happen--

The car would seem like it would downshift- back down to about 1.9K. And then it would quickly- like more quickly than a sedate, standard- NON SPORT MODE- acceleration and change through the gears should require-rev back to 2.4K or so...

4th gear change- about 2.6-3K. (maybe)

The rest of the changes and associated engine sounds progressed as normal.

The real clincher was the ONE time that it did it in manual mode. It was key to point somewhere other than the transmission after progressing through the testing. I tested what would happen if switching to sport mode from 'normal' for a few months, then finally just trying manual mode. When it did it there (only once), I knew something was amiss and I was more certain that it wasn't the transmission- Especially on an X5 with (now) only 22K miles that had behaved this way since 11K miles last year.

[4x4coots]

That's odd, I think I've experienced a similar issue, but it's not consistent as you pointed out. It would shift much lower than I expected and also "feels" rough. I will have to stop by the dealer and have them run the GT1 and see what they come up with.

Thanks for posting this!