Light stumbling between 2-3K

[TXRedDevil]

Gents,

I have noticed that somewhere in the 2-3K range that there's some light hesitation / light stumbling when pressing on the accelerator. Not mashing it, but a little more pressure on the accelerator (i.e., passing a car). Feels a little jerky to put it in layman's term. Plugs were replaced at 74K, so maybe a fuel delivery issue? Any recommendations on what to check?

[san]

Were the DISA and/or VANOS replaced anytime?


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[TXRedDevil]

San,

No to both. I plan on replacing the Vanos seals sometime in the next few months. I'll have to research what DISA is.

[fredo]

More info here:

http://www.zhpmafia.com/forums/showthread.php?18796-4K-Dip

[TXRedDevil]

Fredo,

Thanks for the link. After a couple of pages of reading and I think I understand the options to the fix, but it doesn't seem that unplugging it has 100% solved it for everyone. I'm going to unplug it, but it seems that the safe thing to do is to rebuild it mainly to make sure that the pin doesn't fall out. Is my understanding correct? One thing that I didn't read though: if the BMW code fix renders the DISA inoperable by leaving the flap open, why not just remove the DISA?

[Fried_Chicken]

Firmware up to date?

[TXRedDevil]

Firmware up to date?

I actually don't know. Do I need to go to the dealership to find out and to perform there?

[BADCLOWN]

A rebuild of the DISA and making sure the car is running the most current firmware nearly always fixes this issue. Not guaranteed, but most have success with it.

My first ZHP needed both, my second (current) ZHP never had the stutter but I had the DISA done as preventative maintenance

[John in VA]

A rebuild of the DISA and making sure the car is running the most current firmware nearly always fixes this issue. Not guaranteed, but most have success with it.
My first ZHP needed both, my second (current) ZHP never had the stutter but I had the DISA done as preventative maintenance
How do you know what firmware you have, what is the latest/most current & how do you update it? Thanks!

[TXRedDevil]

A rebuild of the DISA and making sure the car is running the most current firmware nearly always fixes this issue. Not guaranteed, but most have success with it.

My first ZHP needed both, my second (current) ZHP never had the stutter but I had the DISA done as preventative maintenance

Great to know, thanks. I bought the German Auto rebuild kit (think you guys call it the GAS kit) and it'll be delivered some time next week. On another note, I unplugged the DISA harness but I can still feel a little bit of the stumbling slipping. I think the seat of my pants tells me it's a wee bit better.

[BADCLOWN]

That mixed with a firmware update should, hopefully, get rid of that for you

[TXRedDevil]

Badclown, et al:

Thanks gents for the advice to replace the DISA parts. Turns out that the DISA flap/valve or whatever you call it was loose as a goose. No spring back or tension whatsoever. Using the first vacuum holding test, the flap was too loose and didn't snap open. I had to use the second method to test the vac (press in that arm into the vac pot and release) and mercifully the vac pot was still in good shape.

I do have a question for y'all. Take a look at my flapper right after I remove the DISA. This doesn't look normal or is it? Every YT vid I've seen, the flapper isn't covered in this much gunk.

https://i.imgur.com/hIsK9Ubl.jpg

The parts replacement was actually kind of fun and soothing. Felt good to fix it to normalcy using the GAS kit. Scraping out the old gasket was easy with a micro screwdriver that fit right into the gasket grove. I don't know how people do it with a pick :) Pics of it all installed (sans the o-ring) and cleaned up:

https://i.imgur.com/YyQIu00m.jpg

https://i.imgur.com/tRUwdWGm.jpg

Taking her to work tomorrow and take the long route. Looking forward to seeing if it made a difference. Oh, the BMW USA customer service folks told me over email that I would have to go into a BMW dealership to check on the software version. Haha, I think I'll defer that visit for a while unless it's free.

EDIT ON 11/15: YAAAAAS! That annoying stumbling is gone! Drove to work this morning and found several stretches along the way to see if the slipping/stumbling was there. Nope, not at all. I'll have to do some freeway testing too, but so far so good. After handling the old DISA and how loose it was while twisting the flap in certain spots, I can imagine that the looseness was causing irregular and/or buffeting the air flow.

Serious win here, thanks y'all for steering me in the right direction.

[johnrando]

Win!

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