Fellow BMW techs...especially those with 4.6's
 

As a BMW technician working basically on my own I rarely see, much less work on another E53 4.6is. See loads of 3.0's and 4.4's though.

I have an 03 4.6is bone stock with 97k miles. I've had the truck about a year and love it so far. Though I will say that coming from an E38, I can't tell it wasn't built in Germany and isn't nearly as smooth. But, it's got a fat V8, makes great sounds and looks damn good!

Couple nagging problems that are irritating and software hasn't cured.

-When taking off, especially when cold, acceleration just isnt smooth at all. It's not a shifting concern because I 90% of the time use manual mode which eliminates the typical "bang" into first every few stops. It's more like the engine has a lean spot or something. It's really "herky jerky" and annoying. It seems to get better when warm but I still notice it. Is this just a trait of the higher comp. 4.6 variant? Any other 4.6 drivers notice this?:rolleyes:

Also, the aforementioned transmission slam at a stop which is rediculous. My 740i always shifted creamy smooth. The only way I've found around it is to drive in manual mode and gently downshift myself and it never happens.
I've flushed the trans using factory Esso fluid, changed the fuel filter, air filter, plugs, intake gaskets etc. All the usuals when buying a used Bimmer.

Sorry for the novel-like post! Anybody with the patience to read it I hope will have some advice, experience with this.

Thanks in advance!;)

-Ben "BMWTEK"

Have you read about 'the lurch' ? Common problem. No clear remedy.

No, I haven't but I'll search that. This problem occurs probably more between the 2k-3k rpm range more so than anywhere else. Thanks for reading my long post!

-Ben

Do a thread search and you'll find a lot of info on transmission issues, particularly the ones you describe above. Here is also a good read:

Jaguar S-Type ZF Gearbox Lurch fault

Eh, I've read much longer posts than that just in the politics section. ;)

As a fellow BMW tech with a 4.6is at 97k miles I understand what you're talking about. I think what you are feeling with the acceleration is the VANOS kicking in as it seems to do it pretty suddenly on the 4.6is for some reason. It felt so much better for the first couple weeks after I reprogrammed the DME and cleared tranny adaptations last year. (used latest version of progman as ista was too unreliable on older stuff at that time)

Being a BMW tech (or are you at an independent?) you could try that first to see if it makes a desired difference. If it does maybe consider the dinan software as it should open the VANOS solenoids earlier and under slightly less load making the power jump seem smoother.

As for the tranny, I usually don't see that issue on the 4.6is as much as any other model because of the beefed up internals etc. But if you clear tranny adaptations then drive pussy-footed for a day or so it may help clear it up a bit, if not it might be more mechanical than control in nature.

my trans occasionally has a hard downshift into first, but it only happens on maybe 10% of stops - seems to happen more often with very slow braking - when you brake hard, it almost never happens. I don't bother running in manual mode to avoid it because it doesn't really bother me and doesn't occur all that often. Seems like a programming issue to me because certain specific conditions bring it out. Probably the Dinan trans tune would cure it, but otherwise I love how the trans works, so it is something I am willing to live with.

I don't really notice the non smooth take-off - is this under light throttle, medium throttle, 3/4 throttle? My 4.6 is a super smooth operator under just about any situation. I think the 4.6 motor and the Alpina tuned ZF is one of the best drivetrain packages in any car or truck I have ever driven. Close second is the Nissan Titan, but that is a very different animal - but put that motor in a mid sized SUV with some fat tires and responsive chassis and you would have something. Oh wait - no need, we have something in our X5 4.6is models already!! Cheers!!

PS - mine has 108K on it, 13K of those put on since I got it.

I never really have the harsh downshift... maybe 1% of the time as I did get a mild case of it once after a long highway drive with truck and trailer loaded down. (after unloading truck and trailer) But not really since then.

Clean your throttle body and your MAF sensor. Two easy things to do.

Thanks for the replies guys. I failed to say that I have researched 'the lurch" issue extensively I just didn't know that's what it was called.

Weasel- Thank you for the technical reply and it at least eases my mind that someone else has experienced this. I was a dealer tech for about 5 years but now I work at an independant, basically a sub-contracter for the shop itself as i'm the only factory trained BMW tech locally here.

I do have GT1 with Progman which is about 2 years old. I reprogrammed with this but I'm sure it's not the latest version. I may give the Dinan a try if I can find it to be worth the 3-400 bucks...

Since your intimate with your ride I have a couple more questions.

-What tires are you running?

-Do you have any squeaks or rattles? Especially from the rear gate?

Thanks in advance!

-Ben

Exactly like mine, but just like you I dont really get bothered by it!

rear gate noise! http://www.xoutpost.com/search.php?searchid=2246510

search "trunk noise" and u will find a plurality of other posts. i've tried a few to eliminate my trunk knock/thud and its minimized it a little bit

I cant say much about "engine when cold..." C4Racer's explaination is exactly how it feels (is) with mine and I dont think its has to do with being cold, I normally have the 'bang'/jerky when slowing to a stop at anytime of the day the key thing is how you apply the breaks - suddenly you dont feel a thing, slowly it jerks to a halt. But to save break pads which are damn expensive (this side of the earth!) I break slowly unless emergency, breaking slowly also comes with the bang effect.. so what can we do!:dunno:

Vredestein Ultrac SUV Sessanta. Get them in the group buy for a price that will never be available again!

I have the Toyo Proxes on mine. I would say these are good for at least 25K miles at least in my driving pattern which is dominated by highway.

My 20's still have the original style michelin diamaris on them, but I'm due for a new set on them and am going with the bridgestone dueler HP's for my next set if I don't get this set of michelin latitudes I'm trying to get a deal with. (and I mean deal!) I'm currently driving on some 18's I picked up for going to the hunting camp, which have the OE michelin energy tires. When those wear down I'll either throw some mud tires on them for the camp or sell the wheels through here for cheap.

Hey Weasel - You're not interested in the Vred's?

Not really... they may handle good, but wear too fast. I am getting the deal of the week on a set of brand new Michelin latitudes anyways... Gotta love my boss! (how many of you guys can say that?)

i have a 2003 4.6is and the rear ender (leaching) problem is there Weasel, if you have a fix do tell

Unfortunately there is no clear cut solution. In some cases just the software update is enough, in some the valve body, in some the control unit, and some end up with a whole new tranny. I'd say start with the simplest and least costly options, then go up from there since the whole thing tends to be a gray area.