hiccup when starting out right after clutch is released fully=vanos??

It used to be once in a blue moon, but is getting more common. I will go to acclerate mildly, and it seems just about the same time as the clutch is fully released it will hiccup, almost like the engine cuts out for a *very* brief second. It is not me letting out the clutch improperly, it is definately something with the engine. It also does not do this on spirited or all-out takeoffs, just mild/normal acceleration. I've read the vanos symptoms and it seems similar, but I cannot pin point a specific RPM it is doing it at, but it is definately lower(sub 3k). No one seems to mention the failure characteristics if you are driving a manual...... but this seems like it.

Can anyone confirm this?

I don't think this is a normal vanos problem.
I'd be more suspect of a failed DISA. Have you replaced this recently?

Have not, but I inspected it when I cleaned the throttle body and all seemed to be in good shape......

also, it does not have, nor ever had the tell-tail rattle of the DISA failing. I should also note the engine other than this runs absolutely perfect, idles perfect even when started cold in 30* temps, and is returning 22mpg with spirited driving.

bump....no one has any ideas other than DISA?

DISA isnt supposed to kick in until 4100 RPM. If the VANOS have never been done I would highly recommend it. Easy DIY.

My car does the same thing under 3K and it's a manual. New DISA, OSV, spark plugs, air filter, cam intake/exhaust sensors, accelerator pedal module, you name it. Also did the clutch release sensor spacer mod, didn't help. Tried loading different software versions, no change.

I have not performed the VANOS seals update yet, but I don't suspect it helping much.

Yeah, I don't think the vanos symptoms encompasses the hiccup. Of course this can be double checked at the http://www.beisansystems.com/ site, which is completely thorough.

My car does this as well ('99 323i w/139k) ... but randomly. I could have great launches all day, then boom, like op said "car cuts out". I watch the tach dive then come back up while I'm keeping constant pressure on throttle. Very frustrating.

I've done to date: New clutch at 120k (did same thing before clutch install), New plugs, O2 sensors, Vanos seals, VCG, new intake boots, CCV, cleaned disa w/new gasket, cleaned ICV w/new gasket, cleaned throttle body w/new gasket, cleaned MAF, disconnected MAF, new clutch slave cylinder, and did the clutch switch mod. All with the same "random" result.

I even tried checking for stored codes with my Peake but to no avail. I bought some new vacuum lines I'll be installing soon and see if that affects anything. But again, no codes, so I doubt it. I also have a new clutch master cylinder, but haven't installed it yet.

Verrry interested in this thread.

VANOS symptoms can include the hiccup, good description here from the founder of beisan systems:
http://forum.e46fanatics.com/showthr...vanos+solution

If they haven't been done I feel it is worth the trouble and 100 Dollars or so when you throw in a VCG. Made a huge performance difference in our 328 with 240K.

Originally Posted by ddaniel1

VANOS symptoms can include the hiccup, good description here from the founder of beisan systems:
http://forum.e46fanatics.com/showthr...vanos+solution

If they haven't been done I feel it is worth the trouble and 100 Dollars or so when you throw in a VCG. Made a huge performance difference in our 328 with 240K.

To date there are 2,051 posts at the thread you've directed to. This isn't exactly pin-pointing the spot where the hiccup is attributed to the vanos seals.

Ok from the thread: "What are the symptoms of a failing vanos?
On autos with the M52TU engine (98/99-00) the failing vanos is causing engine idle jolts (dramatic drops) and possibly a stall on cold engine starts (< 55 F / 13 C).
On other cars with the M52TU, M54, M56 engines, car performance will be degraded. The engine will bog and hiccup at lower RPM's (< 3k). There will also be a general loss of torque and power, mostly at lower RPM's (< 3k)."

Also from the thread posted above, a test I didn't see before in post 25:
Here's a method for attempting to gage the vanos failure degradation. Get the car in third gear at ~1500 RPM on an incline. Fully depress the throttle. With a failing vanos unit the car will bog and clime very slowly. With a well functioning vanos, the car will have good torque and acceleration.

ALL the vanos units are failing. The O-rings simply do not handle the engine environment. There can be grades of failure. This will depend on time of use and spirited driving. Sports driving will cause the engine oil temperature to peak and will intern cause increased damage to the O-rings.
In my experience from inspecting many O-rings and speaking with many owners who have performed the repair, ALL the vanos O-rings are badly damaged."

I had the dancing idle when cold, which was what led me to doing the VANOS seals, this being my first BMW I thought the power and responsiveness were normal before the VANOS, after the VANOS it was night and day performance wise.

Originally Posted by ddaniel1

Also from the thread posted above, a test I didn't see before in post 25:
Here's a method for attempting to gage the vanos failure degradation. Get the car in third gear at ~1500 RPM on an incline. Fully depress the throttle. With a failing vanos unit the car will bog and clime very slowly. With a well functioning vanos, the car will have good torque and acceleration.

ALL the vanos units are failing. The O-rings simply do not handle the engine environment. There can be grades of failure. This will depend on time of use and spirited driving. Sports driving will cause the engine oil temperature to peak and will intern cause increased damage to the O-rings.
In my experience from inspecting many O-rings and speaking with many owners who have performed the repair, ALL the vanos O-rings are badly damaged."

I had the dancing idle when cold, which was what led me to doing the VANOS seals, this being my first BMW I thought the power and responsiveness were normal before the VANOS, after the VANOS it was night and day performance wise.

no real inclines to speak up here in florida! I will give this a try though, thanks for posting!

Mine has 96k and has been experiencing the same "hiccup" symptoms for a few months. It gets worse as the engine warms up. When I first get in in the morning it works as it should but gets worse quickly. I have also started to notice that my mpg gauge dances when I depress the clutch fully. I am interested to see what the verdict is, I was going to start searching for vacuum leaks.

my 330i does exactly the same, 131k, good disa, eu2 tune, new plugs, fuel pump, 02's etc original vanos???

Originally Posted by riscal33

Mine has 96k and has been experiencing the same "hiccup" symptoms for a few months. It gets worse as the engine warms up. When I first get in in the morning it works as it should but gets worse quickly. I have also started to notice that my mpg gauge dances when I depress the clutch fully. I am interested to see what the verdict is, I was going to start searching for vacuum leaks.

exact same issue on mine too, i just did my vanos 2 weeks ago but I'm not how long it takes for it to be worked in, curious to know if thats the reason!! please let us know if anyone figures out the problem

Originally Posted by edz2003

exact same issue on mine too, i just did my vanos 2 weeks ago but I'm not how long it takes for it to be worked in, curious to know if thats the reason!! please let us know if anyone figures out the problem

So you have replaced your VANOS seals and still are experiencing the hiccup? That is discouraging.......

Just wanted to update and say that replacing my pre cat 02 sensors appears to have fixed the problem. It has not done this all week since they were replaced. Was not throwing any codes, just did it at 120k miles since bmw recommended it 20k ago!

I did EVERYTHING to my car short of replacing clutch/flywheel/pressure plate and still have this low rpm hiccup/violent surge. The engine delays at mild/moderate/heavy takeoff, then after a second, acceleration kicks in hard. I did everything everything everything. I did the oxygen sensors. Still have the problem.

To avoid it, I just take off gently and proceed as normal. Nothing else abnormal. Engine purrs smoothly, no idle problems, etc. pulls strong to redline. VERY strange problem which I really want to get to the bottom of...

Originally Posted by E46Mango

I did EVERYTHING to my car short of replacing clutch/flywheel/pressure plate and still have this low rpm hiccup/violent surge. The engine delays at mild/moderate/heavy takeoff, then after a second, acceleration kicks in hard. I did everything everything everything. I did the oxygen sensors. Still have the problem.

To avoid it, I just take off gently and proceed as normal. Nothing else abnormal. Engine purrs smoothly, no idle problems, etc. pulls strong to redline. VERY strange problem which I really want to get to the bottom of...

Sorry to hear that, but i'm glad I at least seem to be having better luck! My Vanos has still not been done yet fyi, but i'm planning on waiting till the vcg starts to leak prior to doing that.

If it returns I will let you know, It irritated the who know what outa me!