[wahooooman]

i have the same issue, 07 335xi auto, going to bring it in and see if they can figure it out. it happens pretty often around 40ish mph, but not always the same gear or rpm. but it happens alot in DS like 80mph when you give it some gas. but like most dealerships im sure they'll just say oh the tech could not replicate the problem . so i guess ill have to take the tech for a joy ride and pin it to the floor at 80

[RoundelM3]

Hmmm...interesting...the plug replacement wouldn't be that difficult or expensive, although I only have just over 30,000 miles on my car despite it being close to 5 years old. The carbon on the valves thing is another thing entirely - this wouldn't be cheap to fix, and I wonder if BMW is going to offer some sort of 1-time deal on cleaning them? Also - does anyone have any idea on when this buildup gets to be a problem? Seems like it was always closer to 50K miles from the other posts I've read.

That said, it does seem to fit that if the carbon is causing hot spots that might induce preignition, the computer would retard the ignition or whatever it does to preclude actual detonation, and that would explain the "hiccup". I'm gonna see what my SA says about this and try to find out if there are any SIBs out about it yet. Thanks for the updates, guys!

[bucktown]

Originally Posted by roundel335

Hmmm...interesting...the plug replacement wouldn't be that difficult or expensive, although I only have just over 30,000 miles on my car despite it being close to 5 years old. The carbon on the valves thing is another thing entirely - this wouldn't be cheap to fix, and I wonder if BMW is going to offer some sort of 1-time deal on cleaning them? Also - does anyone have any idea on when this buildup gets to be a problem? Seems like it was always closer to 50K miles from the other posts I've read.

That said, it does seem to fit that if the carbon is causing hot spots that might induce preignition, the computer would retard the ignition or whatever it does to preclude actual detonation, and that would explain the "hiccup". I'm gonna see what my SA says about this and try to find out if there are any SIBs out about it yet. Thanks for the updates, guys!

my issues (hiccup/hesitation) started to become obvious at around 50-60kms. i also started to burn more oil around this time. the dealership had me monitor the oil consumption while they started a puma case for me regarding a new engine. then, the head tech had to take some pictures of my odo relating to my fuel consumption for a few thousand kms, submit to the powers that be and bam new engine. no more oil burning, no more hiccups.

he had taken me back to show me the intake mani and the valves and stated definitively that it was the cause of my issues. had he known that that was the issue before pulling the motor im sure the procedure would have simply been to pull the intake and clean the valves. but, based on the lack of other instances to draw from, a new engine was the easiest course of action at that point (and im certainly not complaining about a new engine 10k before warranty ended)

good luck!

edit: also i was told my my tech buddy today that you should check your wastegate vacuum lines and boos pressure hoses upstream of the wastegate actuator, especially if your getting hesitation/stumbling under high load demands on the engine (5&6 gear pulls on highway etc) without throwing codes. check for leaks, cracks, or bad connections. he said that it has started happening to "higher" mileage cars and produces the exact same issues. (and is an easy fix)

[RoundelM3]

Thanks for the info. No stumbling/hesitation out on the highway, just those 3/4-gear WOT runs where it hiccups once in awhile. Everything under the hood looks okay, no weird noises at idle with hood open, etc. But I'll keep an eye on the hoses and such. Awaiting a reply from my SA to see what she can find out.

[galahad05]

You can always try "blowing the carbon out". Old school trick, this.
You warm up your car gently, then, when up to operating temps, you drive it hard and steady for a long run--say, 20-30 minutes.
That doesn't mean you go 100 mph. You just put the engine under load, going highway speeds in a low gear--4k RPMs @ 60 mph, for example.

Make sure you don't overheat.

This tends to burn off any of the oily gunk in the combustion chamber and some of the stuff clinging to the back of your intake valves. Something like your oven's cleaning cycle.

[RoundelM3]

^Yeah, I remember my dad doing that back in the day...I've got some open road nearby so I'll give that a try. Thanks for the suggestion.

[Quisp]

I have been having this problem since I had my car in for the Fuel pump INjector software recall. Got new pump, 4 new injectors and the software. Then got my Dinan reflashed.
When I am going along in 3rd or 4th gear and accleerate hard the car begis to surge, chug, oscillate, or any other synonym. Feels like my foot is going up and down on the pedal very fast. Dyno showing this is below.
Got new plugs, didnt fix it. Dealer said possible lean misfire on one bank and to get a valve cleaning. Hand cleaned the valvea and manifold and $700 later the car runs better but still does the chug.
Been in contact wth Dinan to see what they can figure out and they are going to take my can and see what they can figure out. It goes in on monday.
My theory, and this is just me talking, not Dinan or BMW. I think that there is a new version of the BMW software and something in it is different and messes with tunes. I have seen other forums and thread s with other people who have different tunes but similar problems after fgoing to the dealer.
I will update here when i find something out.

[sonorous]

Originally Posted by Quisp

I have been having this problem since I had my car in for the Fuel pump INjector software recall. Got new pump, 4 new injectors and the software. Then got my Dinan reflashed.
When I am going along in 3rd or 4th gear and accleerate hard the car begis to surge, chug, oscillate, or any other synonym. Feels like my foot is going up and down on the pedal very fast. Dyno showing this is below.
Got new plugs, didnt fix it. Dealer said possible lean misfire on one bank and to get a valve cleaning. Hand cleaned the valvea and manifold and $700 later the car runs better but still does the chug.
Been in contact wth Dinan to see what they can figure out and they are going to take my can and see what they can figure out. It goes in on monday.
My theory, and this is just me talking, not Dinan or BMW. I think that there is a new version of the BMW software and something in it is different and messes with tunes. I have seen other forums and thread s with other people who have different tunes but similar problems after fgoing to the dealer.
I will update here when i find something out.

This is very interesting and informative! At least we can check the items that were ineffective off the list. I anxiously await further updates.

I am not completely sure that it is tune related. My theory is that a tune simply amplifies the issue and there may be many more people with the phenomenon that just can't feel it. Also, it would seem that a 6MT car would display the issue more easily since it is easier to go WOT at a low RPM in a high gear without the tranny jumping to a lower gear. My car (6MT) does it stock but it is mild and I have felt the issue much stronger on a tuned car. It could be BMW software update related but my car showed the symptoms pre and post HPFP/Injector recall. Maybe I had an update that caused it earlier but I would not be able to place where and when.

Have you already or do you plan to try any of the issues related to the lines and hoses? It seems like another plausible scenario:

Originally Posted by bucktown

edit: also i was told my my tech buddy today that you should check your wastegate vacuum lines and boos pressure hoses upstream of the wastegate actuator, especially if your getting hesitation/stumbling under high load demands on the engine (5&6 gear pulls on highway etc) without throwing codes. check for leaks, cracks, or bad connections. he said that it has started happening to "higher" mileage cars and produces the exact same issues. (and is an easy fix)

[IN54NITY]

Thanks for a great post and graph Quisp!!!

[Doenermann]

Subscribed!

I'm experiencing the high RPM (4500-6000) stutter / jerkiness at WOT am very interested to see the results here as they could possibly be related to my issue (basically what Alex D mentioned last year). I had to get a new BMW flash as well in october last year before Dinan worked and while I love the performance, it's far from smooth. I have this on an N54 powered X6 but the issue should be motor related.

Want to schedule a service appointment soon and it would help to point the techs in the right direction. If I don't, at least at my dealer everything opererates "to spec" more than it really should!

[Quisp]

Here is a short vid I made of it happening. I have been having some serious wastegate rattles lately so that may have something to do with it.

[RaceBlood]

Have you had the latest Software updates?
How many miles you have on the Spark Plugs?

[Quisp]

The latest software is when it all started and the plugs have about 200 miles on them. Only happens when accelerating hard or wot (all gears)

[galahad05]

Interesting.....I too was upgraded to new software as part of the recall campaign.

Could be coincidence.

[sonorous]

Originally Posted by Quisp

Here is a short vid I made of it happening. I have been having some serious wastegate rattles lately so that may have something to do with it.

After looking at the video it does correlate well to the dyno graph and I can understand your symptoms clearly. After seeing this however, I now think there are more than one conditions being discussed on the same thread. My condition is different and I would say not as significant. What you show is a very clear oscillation with a relatively high frequency. What I have and what it seems like others are describing is a hiccuping/shuddering feeling under acceleration. At least for me, it does not manifest itself like a sine wave but more like dips or surges separated by smooth acceleration, maybe 1 sec apart. I am not sure if the causes are the same since the symptoms are so different. In any case I am very interested in your final fix so I am looking forward to any updates.

[335iBatmobile]

test post

[Potty_Pants]

24k miles on my 2007 . most injectors replaced and problem went away (winter time)

now warmer weather problem returned.

there have been a few updates to the dme since my flash... so i wonder if they fixed this problem ?

also replacing plugs hasnt resolved this problem in other test cars... it was like a hit or miss thing... so last i heard dinan was still "working on it" though i'd just return my flash and go back to stock if the possibility arises.

ppp

[RoundelM3]

I'm going to try the "blow out the carbon" fix this weekend. I have a nice limited-access tollway close to where I live, and it's about 57 miles from one end to the other. I should be able to maintain a steady speed at 4K RPM in say, 4th gear and see if this helps. I'll post my results afterwards.

[Doenermann]

Originally Posted by Potty_Pants

... so last i heard dinan was still "working on it" though i'd just return my flash and go back to stock if the possibility arises.

ppp

Was this recent? Just wondering if there is any point in contacting them myself, or if the problem is even caused by Dinan or simply amplified! I've had problems with the tune (since the october '10 BMW and DINAN flash) where it would not start at all or idle would jump and car wouldn't drive, but that has since been fixed via a new throttle body and a Dinan update. But this did not / never affected the stutter which was present from day 1.

My problem is definitely not as severe the dyno graph or the video, and after further testing it does occur all throughout the whole RPM range under hard acceleration... frequently. However, it is most noticable when the car has / feels like it has more power (higher RPM and in first or second gear).

[Quisp]

It is hard to tell if it is surging or dropping. I have heard a few theories form other people such as the targert boost and the boost being too close. The car hits target and the ECU cuts back then boost kicks in again for a second until it hits target again...rinse, lather, repeat. The tricky part is that it only shows up in that rpm range oon the Dyno sheet. Does it in any gear, but only that range. The noise it makes sounds so much like a vacum of sometype. Like you have your hand on the end of the shop vac hose and lift off and on....wow, a description like that, I really should lay off the lucky charms at night

[Potty_Pants]

Originally Posted by Doenermann

Was this recent? Just wondering if there is any point in contacting them myself, or if the problem is even caused by Dinan or simply amplified! I've had problems with the tune (since the october '10 BMW and DINAN flash) where it would not start at all or idle would jump and car wouldn't drive, but that has since been fixed via a new throttle body and a Dinan update. But this did not / never affected the stutter which was present from day 1.

My problem is definitely not as severe the dyno graph or the video, and after further testing it does occur all throughout the whole RPM range under hard acceleration... frequently. However, it is most noticable when the car has / feels like it has more power (higher RPM and in first or second gear).

Yes, Please contact Dinan (THOUGH I DIDNT)... another story.
The more people that report this they will work harder to fix it. or least find out why its happening.

and no the info i have from dinan isnt recent its about 5-6 months old.

ppp

[RoundelM3]

Went out yesterday afternoon and drove for 30 minutes in 4th gear at about 80mph - pretty close to 4K RPM. After I was done, I gave the car some time to cool down (oil temp at 245 degrees), and did a couple of test runs. No noticeable hiccupping, but I'm going to try again today and see if it really worked. If so, this is an easy way to keep it cleaned out.