4000 RPM Power dip in an AUTOMATIC ?

[Mtnman]

I know we have a thread about this problem, but all the posts i saw referencing the service bulletins say this is a Manual Transmission problem only. Well, i have an automatic, and here is what is happening:
At 4,000 rpm's under 2/3 to 3/4 throttle, i have a HUGE surge in power that lasts 500 to 800 rpms. It is most repeatable in 2cnd and 3rd gears. It is such a loss of power that it feels as if i completely took my foot off the throttle with the car in gear. It physically moves my head forward.

This happens about 30% of the time while meeting the above conditions. It also appears to have gotten worse this summer (warm air?)

Does anyone have any ideas here? From what I have read, this seems like classic 4k power dip, but again, all service information bulletins that I have read state Manual Only. HELP!

Moderators, feel free to merge threads if you feel appropriate.

[az3579]

The classic 4k dip isn't the same ad though you took your foot off the throttle; it isn't nearly that bad. I think you may have a special case if it's that bad...

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[Mtnman]

Update on my 4,000 rpm power dip.

I Took the car to the dealer. They checked the software on the vehicle. Everything up to current. Charged me $60. thank god not the full $100. Talking to George, the guy I like working on my car, he suggested maybe it could be the fuel filter being clogged/dirty. Seeing as I had already ordered a new fuel filter and it was in hand, I replaced that this weekend. It did not solve the problem.
I thought it might be the DISA valve. This valve actuates at 4,000 rpm exactly. I took the valve off, inspected, cleaned, and prodded. It was making what I thought to be a strange noise. I took the valve to the dealer and compared it to a new valve. To my surprise, the new valve makes the same strange noise. After reinstalling the old but clean DISA, problem still there.

Damnit.

[BCS_ZHP]

David,
Albeit on a manual car, after I installed the Performance intake which supplies more air, the 4K stumble problem was gone. ECSTuning still has it on sale for under $300.

[anm3itbe]

Looks like David already has the BMW p.intake. Could it be a MAF related issue?

[Mtnman]

I do have the bmw p intake. I inspected the maf when I removed the disa. Didn't see anything visually wrong or dirty. What makes you think maf? I'm open to any ideas right now.

Right now my new mission is to recreate the dip/fluctuations with the a/c off. I'm going to work on the over the next few days and report back to my mechanic. Don't know the full reasoning yet, but it was cpu/sensor related. I will keep posting in this thread until I get it solved (I hope!)

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[mikeyb74]

David, There is a SIB for power dip at 4000K on the M54b30.


Service Measure
Engine Electrical B12 209 05 04/06/2005
Subject
M54B30 MS45.1; Engine Power Drops at 4000 RPM

Vehicle
E46, E60 with M54B30 and manual transmission.

Complaint
Customer may complain of an engine power drop at approximately 4000 rpm during aggressive acceleration.

Cause
Ignition timing retardation due to unfavorable tolerances of DISA valve flap shaft. Vibrations of a DISA valve are interpreted by the knock sensor system as detonation combustion.

Measure
On a customer complaint basis, replace DISA valve with the improved part (PN 11 61 7 544 805).
After DISA replacement, connect vehicle to DIS/GT1 and from DME identification page retrieve the programmed and basic DME part numbers.
Reprogram DME with the latest available DTS CD! SSS CIP software version. DME programming should last for at least 20 minutes and should result in both programmed and basic control unit number changes. Reprogramming of DME clears the long-term knock sensors adaptations. If the knock adaptation values are not cleared, the vehicle will still exhibit the power lack complaint, even with the improved DISA valve installed.

Important:
In the event the DME programming takes only a short period of time (approximately 5 minutes), and the basic control unit part number has not been changed, the adaptation clearing process has not been accomplished.

In such a case, contact Technical Hotline — Drive train via a PuMA case, requesting authorization for DME shipment to Engineering Department for reprogramming. For the PuMA case title use the following: MS45.1 DME KNOCK ADAPTATION RESET”.

http://www.zhpmafia.com/forums/showthread.php?1703-4K-power-dip-dealer-fix

[Washburn]

^^ ...and that' SIB is for MANUALS only. David was asking about AUTOMATICS (see thread title)

[Mtnman]

Yeah, I have read the service bullitens anddd they all say manuals....but it doesn't make sense why they do. I dodnt understand it I guess.

Thanks for posting that mike. we will eventually see if it does apply to me or not.
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[mikeyb74]

David, I was just talking to a friend of mine that just so happens to be a BMW tech about this. He said it is a common problem that he sees with both autos and manuals . He usually would replace the DISA valve with the updated version and have the ECU reprogrammed. But you already had it looked at by BMW.

Are you using the SPORT mode when it does this power dip?

[Mtnman]

I did have it looked at by BMW, but it did not solve it, so im open to any advice! This happens every way. auto, sport, and in auto-manual. its funny, going from regular drive to sport mode in my car does nothing. regular drive at 1/6 throttle will keep the car in gear till 4k rpms....it takes work to make it shift sooner than that. I almost wish they could reset the computer on my shift points...but thats another story. Whats your angle on the sport mode question, Mike?
Oh and for the record, the dip seems to still be there when the AC is off, but it is GREATLY reduced. I am going to investigate this angle further.

[MrMaico]

My guess would be that the difference with the a/c on is just because of the added drag on the engine making it more noticeable. Similar to how people say the 4000 dip is easier to feel when going uphill. Just a guess though.

Slightly OT but when I bought my old 79 320i I wasn't happy with the way it would downshift or hold a gear. It took too much throttle to get it to kick down or hold a gear. One day I noticed a cable running from the throttle linkage down toward the transmission so I just adjusted that cable, basically taking some slack out of it. It transformed the car! Worked great after that....like a BMW should have. You could use the throttle to control the trans so much better. Too bad that now days with electronic auto transmissions there are no easy adjustments like that to be made.

Barry

[Mtnman]

My thoughts exactly Barry.

and I wish I had a cable. much easier to tweak than a computer!

[otisdog]

So I just read SIB 12 17 05, and it says it only pertains to manual transmission vehicles. Does anyone here have a auto trans that experiences the 4,000 RPM stumble?