Regarding a possible problem with the IACV, I had created and then fixed a problem with very similar symptoms many years ago on my 2001 3.0i. So in that case, there was no doubt about the cause, effect, and solution. I basically took a car that should run well, cleaned the IACV while I had it out, and that cleaning actually caused a problem by freeing up some gunk, causing the valve to not move freely, giving the very slow driving start. Removing and cleaning the IACV more carefully showed the problem (IACV clearly sticking) and solved it.

Here is a thread (which may be relevant in other ways for you) in which I tell the story with a little more detail, and also is probably more accurate due to being older.

https://xoutpost.com/bmw-sav-forums/...cant-find.html

As far as how smooth and well these cars should drive, I will say that of the dozen or so cars I've owned, this is the absolute smoothest and easiest to drive - pulling away from a stop with smoothness, power, no delay, etc. I bought the car as a first car for all my kids to use, and it was perfect for that - safe, easy to drive, relatively cheap to own/operate/insure.

Thanks all for the excellent info and suggestions. I'm going to try:

• Cleaning and lubricating the IAC w/ throttle body cleaner, making sure it moves freely and clicks when gently shaken from side to side. Lubricated with motor oil.
• Clean the throttle plate with throttle body cleaner (although it looked pretty clean already).
• Contact the dealer about this service bulletin. Found through one of the linked threads:
  • BMW issued a Service Measure bulletin for the Throttle response issue. For details ... look up service measure B12 204 04. The DME software needs to be updated.
• Run BG44k in the fuel for at least another tank (been running one tankful already) to try and loosen the carbon deposits on the piston crowns.
• I debated pouring solvent directly into the cylinders such as carb cleaner or ACDelco top end cleaner but this makes me a bit nervous, so I will table this for now.
• I had some BG EPR on hand so I went ahead and used it (supposed to clean out deposits in the oil system), changed the oil.
• I will try the "Italian tune up" and make an attempt to drive it a bit harder.
• I verified through INPA that with with light throttle application, the IAC position changes. I don't have a helper so I couldn't try doing this on an actual drive, and I couldn't give enough throttle in neutral without over-revving the engine to actually get the throttle to open.

I call it a “Clean Out”.! The wife is always saying, “knock it off”! And I say, “Ah, I’m just cleaning her out”. But I’ll tell you, seems to work. :dunno:


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Throttle tip-in issue/stumble ([emoji2391].0 [emoji2[emoji2391]9[emoji2391]]-speed)
 

I taught my wife that the BMW needed some occasional "exercise".

Yesterday when proofing out a repair to excise some demons giving her engine some rough running cylinders, took her out on the freeway for some full throttle run.

To my surprise a Vette shoots by me right as i hit about 80.

All lanes clear for about half a mile so "hammer down" caught up with the Vette in a handful of seconds.

HUD indicted 3x36 [emoji1]!

Engine performed flawlessly but then running rough numbers indicate she's overdue some new plugs.

@Masospaghetti--- The dealer should be able to tell you if the programming update has been done, unlikely that it hasn't. If the IAC controls the tip in throttle then I would buy a new IAC motor, good chance someone has used carb cleaner and the o-rings are swollen and dragging a bit.

Called the dealer and that programming actually has not been done but of course it's requires a diagnostic fee of $285 to even start :rolleyes: but probably worth doing to rule it out.


Went for a drive today and the problem persists after the additional IAC cleaning and lubricating.

Is the diagnostic fee taken off programming? Or at least discounted. They will try to find something else to fix.

Well…. You could always take those proceeds and apply them to a Active tune being you have a stick. Pretty sure once the fee is paid, tuning and updating is included thereafter. Double check though. They’ll definitely get that M54 running right! As long as all of your maintenance is up to date.


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Update - installed a new IAC and grommet (Standard Motor Products brand, pleasantly surprised to see it was made in USA) but no meaningful change in the throttle response. Next step will be to apply the software update.

I forgot to mention this in my previous post (#40) in this thread: I have the same throttle delay that seems common to the M54B30 engine, too.

Having never driven ANY BWW previously, I just assumed that it was normal for the species, and have lived with it as-is. It doesn't bother me much, since I mentally & physically delay throttle application while leaving a stoplight, after being a long-time drag racer, and now refrain from full throttle starts (less wear and tear on the old parts).

I've also found that on my other drive-by-wire vehicles (both GM products: a '04 Chevy 2500HD pickup, and a '09 Chevy HHR Panel), they will sometimes go into limp mode if I tromp on the pedal from idle, so I learned to ease into it, to avoid the problem. The '98 GMC pickup, with a conventional mechanical accelerator installed, has no such a limitation (in fact, the previous owner, a friend I bought it from, previously won many drag races driving it).

Now, following this thread, and with the tip-in delay in mind, I did one lead-footed start yesterday while driving the X5. While it didn't compare well to either the GMC, nor to the memory of my 700+HP '66 Chevelle drag racer, it did leap from the light. I think I'll keep a lighter foot, and my intentional delay when accelerating from idle, and restrict full throttle applications to the highway (it shows no tip-in delay there).

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