[lazd]

Hi all,
My vehicle:
Recently purchased CPO 2008 335i steptronic with no modifications and 58k miles.

Problem description:
On two occasions within the past month, my engine has "cut out" for a split second when accelerating under wide open throttle. The car will be accelerating fine around 5000 RPM, then will suddenly lose all engine power (not electrical, iDrive and dash are unaffected), then resume accelerating at full force less than a second later, resulting in quite the jolt and a drop in RPMs.

Supplemental information:

• No lights are visible in dash during power loss (DTC is not flashing).
• This is in the near the top of a gear (but not during a shift).
• I cannot recall if I was in DS (sport mode) or not, but I was definitely not in steptronic (manual) mode.
• I have not read codes yet, but I do not have check engine or any warning lights.

Research:
I searched extensively and found the following posts which describe the same issue (though they're on different or modified cars):

• N54 acceleration problem: modified 335i, OP reports problem is still unresolved
• N54 acceleration problem: poster says stock 335i had same problem as OP, poster reports problem went away on its own
• 330i Loses power randomly: Poster suggest fuel filter, OP reports back with success
• 335d Acceleration Flat Spot: Posters suggest "gearbox reset" and suggest it may be due to traction control, OP does not report back

Has anyone else seen and/or resolved this problem?

The only suggestion reported as successful is replacing the fuel filter. Can anyone attest or refute this solution? Does anyone have other suggestions?

Please let me know if I can provide additional information. I appreciate your help and value your time!

Update: A number of people have reported similar problems and a variety of causes:

• ed.w's 330i: @ 40k: Bad fuel filter
• achien's 335i @ 30k: Excessive carbon buildup
• ruphianh 335i @ 115k: Bad throttle body
• pimple's 335i @ 50k: Bad ignition coils

Others have reported, but not fixed:

• lazd's 335i: @ 58k: (this post)
• e90fun's 335i @ 45k: Sudden loss of power and odd sound
• rismo123's 335i: Sudden loss of power 5700RPM+, 4th & 5th
• pits200's 335i @ 45k: Sudden loss of power 2nd & 3rd
• DefactoM6's 335i @ 28k: (same problem)

[marv85]

do you have a BT tool? so you can read the codes. May be that will help you debug faster.

[lazd]

Originally Posted by marv85

do you have a BT tool? so you can read the codes. May be that will help you debug faster.

I do not. (Bavarian Technic Diagnostic Tool, correct?).

I assume I can read the codes at a local auto parts store or dealership, as well. I will do that this afternoon and report back.

[pits200]

This is funny, I kind of have the same issue under full throttle but mine is in the higher rpms close to the shift point. It's fine from 1st to 2nd and it happens from 2nd to 3rd or 3rd to 4th most of the tine.

I never have any issues under regular driving and spirited runs where its not 100% throttle. No errors or lights or codes.

I have changed my spark plugs and am on the new hpfp.

[marv85]

Originally Posted by lazd

I do not. (Bavarian Technic Diagnostic Tool, correct?).

I assume I can read the codes at a local auto parts store or dealership, as well. I will do that this afternoon and report back.

yes that is correct.

[lazd]

Originally Posted by pits200

This is funny, I kind of have the same issue under full throttle but mine is in the higher rpms close to the shift point. It's fine from 1st to 2nd and it happens from 2nd to 3rd or 3rd to 4th most of the time.

I clarified my original post; it seems to happen around 5000-5500 RPM, and yes, it was in 2nd or 3rd gear for me as well. So it seems we have precisely the same problem.

[Spoolin335]

I have had the same issue. It only seems to happen when its really hot outside. I can do WOT runs while its cold with the exact same map setting and not get any issues.

Also, there is no codes or anything. I have the BT tool so i can instantly check after i get a little blip in power.

I have no idea what the issue is either...
I want to catch it sometime when im logging and hopefully we can finally find a solution.

[pits200]

Mine happens regardless of the weather, it has probably done it about 4 times now in the past 6 months. I am fbo using the Procede as my tune. My spark plugs only have about 5k miles on them and I still got the problem even after they were installed.

[lazd]

Originally Posted by Spoolin335

I have had the same issue. It only seems to happen when its really hot outside. I can do WOT runs while its cold with the exact same map setting and not get any issues.

Both times this happened for me, the weather was cold (56° F).

[Beemw335]

If you cant log..just take a video of wot so we can see.
or just dealer it!

[pits200]

I think the issue for the few of us having this is that it is somewhat intermittent and doesn't happen all the time.

[ruphianh]

Originally Posted by lazd

Hi all,
My vehicle:
Recently purchased CPO 2008 335i steptronic with no modifications.

Problem description:
On two occasions within the past month, my engine has "cut out" for a split second when accelerating under wide open throttle. The car will be accelerating fine around 5000 RPM, then will suddenly lose all engine power (not electrical, iDrive and dash are unaffected), then resume accelerating at full force less than a second later, resulting in quite the jolt and a drop in RPMs.

Supplemental information:

• No lights are visible in dash during power loss (DTC is not flashing).
• This is in the near the top of a gear (but not during a shift).
• I cannot recall if I was in DS (sport mode) or not, but I was definitely not in steptronic (manual) mode.
• I have not read codes yet, but I do not have check engine or any warning lights.

Research:
I searched extensively and found the following posts which describe the same issue (though they're on different or modified cars):

• N54 acceleration problem: modified 335i, OP reports problem is still unresolved
• N54 acceleration problem: poster says stock 335i had same problem as OP, poster reports problem went away on its own
• 330i Loses power randomly: Poster suggest fuel filter, OP reports back with success
• 335d Acceleration Flat Spot: Posters suggest "gearbox reset" and suggest it may be due to traction control, OP does not report back

Has anyone else seen and/or resolved this problem?

The only suggestion reported as successful is replacing the fuel filter. Can anyone attest or refute this solution? Does anyone have other suggestions?

Please let me know if I can provide additional information. I appreciate your help and value your time!

I had a very similar issue. It turned out that the throttle body went bad. The throttle body couldn't make the request from the computer and the car would just "stop". When I mean stop, I mean like a terrifying jolt, and then continue. It would happen under high load, 3-4k RPM's when boost was at a max. It became more and more frequent as time went on.

I finally brought it into a BMW dealership becuase I wasn't throwing codes at first. Eventually I got a code for throttle body position sensor or something like that.

EDIT:

Just some additional info:
Car had around 115k miles when issue happened
It happened when I was running stock maps
The fix was under $500 dollars for a new throttle body assembly installed.

[ruphianh]

Originally Posted by ruphianh

I had a very similar issue. It turned out that the throttle body went bad. The throttle body couldn't make the request from the computer and the car would just "stop". When I mean stop, I mean like a terrifying jolt, and then continue. It would happen under high load, 3-4k RPM's when boost was at a max. It became more and more frequent as time went on.

I finally brought it into a BMW dealership becuase I wasn't throwing codes at first. Eventually I got a code for throttle body position sensor or something like that.

Also, try throwing it in M5 or M6 at low RPM and max the throttle without hitting the kick down on the freeway. Eventually this was the best way to make the car do the jolt.

[pimple]

Sounds like a misfire condition. Ignition coils were my culprit.

[e90fun]

Sub'd

I have the same problem on the track running on anything higher than stock map.

It seems to be continual misfires but if I run on stock map, everything is fine besides the occasional limp mode..

[pits200]

Ok so for all who have this issue, lets get some info.
Mods
Year
Mileage

I'm

FBO using procede
2009
45k

Is it possible its or DVs are weak and aren't able to hold the max boost we are running? This seems unlikely but it would help if I could get this to happen when logging.

[Tzu]

Sounds like a run of the mill misfire to me.

Pits200: why dont you pressure test your DVs? Are yours stock?

[DefactoM6]

FBO+Meth, Procede, '09, 28k. Stock DVs.

[marv85]

Originally Posted by e90fun

Sub'd

I have the same problem on the track running on anything higher than stock map.

It seems to be continual misfires but if I run on stock map, everything is fine besides the occasional limp mode..

did you read codes? limp mode code is usually accompanied by other codes that may help you locate your issue

[e90fun]

Originally Posted by marv85

did you read codes? limp mode code is usually accompanied by other codes that may help you locate your issue

The CAN clear was on and deleted all the codes when I went to read them, since then I have turned it off but have not been able to replicate the "stall" in power on the streets.

Might have to wait till the next track day but what I am guessing is that it is the coils.

Im 45k 08 AT.

FBO + JB4.

Fresh spark plugs just tossed in at 44.5k.

[marv85]

Originally Posted by e90fun

The CAN clear was on and deleted all the codes when I went to read them, since then I have turned it off but have not been able to replicate the "stall" in power on the streets.

Might have to wait till the next track day but what I am guessing is that it is the coils.

Im 45k 08 AT.

FBO + JB4.

Fresh spark plugs just tossed in at 44.5k.

at that mileage, I got a couple of limps and it turned out to be the Vanos solenoids. Never had a limp mode since, and I'm now at 75k

[lazd]

Just got back from the dealer. There were no fault codes in any module.

We took it for a spin on the freeway and tried putting it in M5/M6 and giving it full throttle (before the kickdown), accelerating through 1st, 2nd, and 3rd in D, but we couldn't reproduce the issue. We ran through all the obvious; "did you hit the rev limiter? was it traction control?" etc and I made it clear that this occurred in the middle of a gear in dry conditions and that I didn't see DTC lights flash.

The service tech stated that a fault code will ALWAYS be thrown if a misfire occurs. Is this true?

The service tech also stated that, if it was due to the fuel filter, a fault code would be thrown as well. Is this true?

They acknowledged that this behavior was definitely not normal and didn't dismiss the issue, they just had nothing to go on. They said they'll check this afternoon with another tech to see if he has heard of this issue. In the mean time, I will make sure to note exact details (speed, RPMs, gear, ambient temp, oil temp, etc) when/if this issue happens again.