4k RPM Power Dip

[dubfreaks]

Anybody else experience the 4k rpm power dip... I've searched and only found old info on a fix for this, wanted to get some updated info / solutions...

Are there any flash tunes that can correct this as well as increase performance in other areas?

Is this still a BMW dealership only fix?

Updated info greatly appreciated. thanks.

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[Newjack]

Yeah the 4k dip is a very well known issue on the ZHP. Pretty much everyone has experienced it and everyone has various solutions to it. Sometimes it comes back and sometimes it doesn't. There are a ton of different threads on the issue if you feel like searching through them. Lots of good discussion and potential fixes

[dubfreaks]

I did search, but as I stated they're all old threads from 10+ years ago.

Yeah the 4k dip is a very well known issue on the ZHP. Pretty much everyone has experienced it and everyone has various solutions to it. Sometimes it comes back and sometimes it doesn't. There are a ton of different threads on the issue if you feel like searching through them. Lots of good discussion and potential fixes

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[Sockethead]

Nothing has really changed. Some people get the latest version of the BMW software, some say a tune cured it, others say rebuilding the DISA helped it. Personally, I did all three...

[Reasoned1]

I never noticed it on my car, but I installed Shark Injector programming right after buying it (18 months ago), and I've read that helps too.

[RUS_ZHP]

The power dip is a very interesting thing. I never experienced it untill two month ago.
My car is 03 with 159k miles. I have TMS software flash that was done almost 1 year ago. Two month ago I stared experience the power dip around 3200 rpm. 4000 rpm seems fine to me. On the second gear it's the most noticeable. First, third and 4th gear are much better. Two month ago I did the following to my car:
Brand new CCV
Rebuild DISA. Old disa was in good operating condition.
Rebuild Vanos with new seals and anti-rattle kit
New VCG
New intake, ICV and throttle body gaskets
TMS under drive pulleys kit

All that was done while car battery was disconnected and not driven for 6 month.
Since the rebuild, I drove 1100 miles. I did a 250 miles breaking period for Vanos, which was recommended by Beisan. Actualy, I drove a bit more to stay on the safe side.
In order to "cure" power dip, I switch back to factory ECM tune. That didn't help. I drove for ~100 miles and switched back to TMS tune. No difference. Power dip is still present.
It is super annoying for me personally. I did all the things listed above proactively. CCV was clogged, but everything else was fully functional. DISA and Vanos o-rings were fine.
The only solution I didn't try is the latest BMW software. I am not sure if I'll be doing this. I generally don't like dealing with dealers.
May be I just have to find our if any of the local dealers will have the latest software version and try that just to eliminate another variable.



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[Sockethead]

Could be that your DISA was malfunctioning even though it appeared to be ok. When you rebuilt it, it started working properly. This was the case with my car.

My theory on the dip is that on a well maintained car with the software updates, etc, what you're feeling is the transition of the DISA opening and changing speed and volume of the intake flow. This is why people say disconnecting the DISA cured the dip...

[cornercarver]

I wish there was a definitive answer on this. I've never really noticed the 4k RPM dip, though there is definitely a substantial hesitation/stumble on mine between 2600-3000 RPM under moderate throttle. (Less noticeable during WOT but it's still there.) It's the place my car spends the majority of it's time and would actually be a very satisfying range if not for the stumble. It feels like the car has the most torque and is pulling really well between 1000-2500 RPM but then it stumbles and feels like shit unless I preempt the stumble with WOT around 2000 RPM and then back off quickly after 3k. It's F-ing annoying and I wish there was a solution because this car is otherwise an excellent DD, as well as a fun weekend corner carver.

I replaced my DISA a few months ago and it had no effect. I also did the Shark Injector shortly after I bought it so I don't know if that made it worse or better. I can't remember how it felt before the Shark tune.

[Newjack]

Could be that your DISA was malfunctioning even though it appeared to be ok. When you rebuilt it, it started working properly. This was the case with my car.

My theory on the dip is that on a well maintained car with the software updates, etc, what you're feeling is the transition of the DISA opening and changing speed and volume of the intake flow. This is why people say disconnecting the DISA cured the dip...

Disconnecting your DISA will remove the dip, but you will have no power low end. Car will drive like crap and you will see yourself reving out each gear in reular driving. Do not recommend.

[RUS_ZHP]

Thanks for the feedback guys. I will disconnect DISA and give it try, just to see if dip will disappear.


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