[arts711]

So my 235 xi has about 80000 some odd miles and has always had its the regular maintenance performed.

if say i'm climbing from 40-70 in a higher gear without flooring it, the acceleration seems to have bumps in it as the engine climbs. I don't hear wheel slip, traction control doesn't come on, there's no noticeable change in rev sound, but there is a noticeable stutter in the acceleration.

that is about as clear as I can describe it and I'm genuinely puzzled what this may be and if I need to take it in to have it checked.

Has anyone else on here experience this before?

Thanks!

[Sportstick]

Originally Posted by arts711

So my 235 xi has about 80000 some odd miles and has always had its the regular maintenance performed.

if say i'm climbing from 40-70 in a higher gear without flooring it, the acceleration seems to have bumps in it as the engine climbs. I don't hear wheel slip, traction control doesn't come on, there's no noticeable change in rev sound, but there is a noticeable stutter in the acceleration.

that is about as clear as I can describe it and I'm genuinely puzzled what this may be and if I need to take it in to have it checked.

Has anyone else on here experience this before?

Thanks!

I'm reacting to your specific comment about a higher gear. Are you sure you have not chosen a combination of speed and gearing that the engine is lugging? If this is by manual selection, does it occur in the same moment in a lower gear? If this is by automatic selection, perhaps the issue is with the trans and not the engine, if for whatever reason, the trans is not downshifting as needed? This is all long-distance armchair speculation, of course. However, whatever the cause, if the engine is lugging, this is not a good idea to let happen for the sake of engine durability. I usually default to taking it in when in doubt...letting it go would just seem too much risk.

[hwntime]

Originally Posted by Sportstick

I'm reacting to your specific comment about a higher gear. Are you sure you have not chosen a combination of speed and gearing that the engine is lugging? If this is by manual selection, does it occur in the same moment in a lower gear? If this is by automatic selection, perhaps the issue is with the trans and not the engine, if for whatever reason, the trans is not downshifting as needed? This is all long-distance armchair speculation, of course. However, whatever the cause, if the engine is lugging, this is not a good idea to let happen for the sake of engine durability. I usually default to taking it in when in doubt...letting it go would just seem too much risk.

This could possibly be the problem if it's a 6MT. I've never experienced such a thing with an auto trans but on a manual for sure if in a higher gear at a moderate speed trying to accelerate. Almost a chattering/stuttering type of feeling until the car gets up to speed. OP is your car a 6MT?

[Sportstick]

Originally Posted by hwntime

This could possibly be the problem if it's a 6MT. I've never experienced such a thing with an auto trans but on a manual for sure if in a higher gear at a moderate speed trying to accelerate. Almost a chattering/stuttering type of feeling until the car gets up to speed. OP is your car a 6MT?

Actually, I have experienced this with a 2018 automatic 3 Series, or something that would fit this general description. If I am too gentle on throttle with my 330xi, in Comfort mode only, it will lug on very slight acceleration at moderate highway speeds until there is enough throttle angle to force a downshift. There is no reason to do this, but the car will continue to lug (as I found out early on) unless I back off or push further. I found this when doing "relaxed" cruising on the highway. Doesn't happen in Sport.

[arts711]

thanks all. A bit more detail.

Its an automatic and its definitely not lugging as I've accidentally done that before in a parking lot. This can pretty much happen in any gear but more noticeable past 2nd and rpm's are typically already above 2.5k.

no CELs, no warnings, nothing.

Happens with all sorts of traction control settings and with the wheel straight, I believe I've even replicated with full off although being winter here and on snow tires (17 inchers), its been a while since I've done that.

If there's any other type of information I can provide or things to try, I will be more than glad to.

[hwntime]

Initially I thought it could be fuel or air related but when you said it only happens in the 40-70 range, it threw a curve ball. You're up there in miles so your plugs and/or coils could possibly be a cause unless you've already changed them. If you've never changed your plugs, I'd personally start there to see if it makes a difference since you should be changing them soon anyway. Is your car tuned? Is it idling ok, no misfires or rough idle? Worse case scenario, take the car in as Sportstick had mentioned.

[Sportstick]

Originally Posted by arts711

thanks all. A bit more detail.

Its an automatic and its definitely not lugging as I've accidentally done that before in a parking lot. This can pretty much happen in any gear but more noticeable past 2nd and rpm's are typically already above 2.5k.

no CELs, no warnings, nothing.

Happens with all sorts of traction control settings and with the wheel straight, I believe I've even replicated with full off although being winter here and on snow tires (17 inchers), its been a while since I've done that.

If there's any other type of information I can provide or things to try, I will be more than glad to.

I am not sure how you can experience lugging in a parking lot at parking lot speeds, as the car would normally be in 1st or at most 2nd and should not ever experience lugging in those conditions.

One simple thing to try is when you feel that happening on the highway, immediately change the mode (not just TC on/off) from whatever it is to something else...Comfort to Sport...Sport to Comfort. Any of those. If the symptoms go away, it should start to help with a diagnosis, although I still think you are dealership-bound.

[bryan_G01]

80mi, wastegate.... turbo next.

try changing your tmap sensors first...

[arts711]

Originally Posted by hwntime

Initially I thought it could be fuel or air related but when you said it only happens in the 40-70 range, it threw a curve ball. You're up there in miles so your plugs and/or coils could possibly be a cause unless you've already changed them. If you've never changed your plugs, I'd personally start there to see if it makes a difference since you should be changing them soon anyway. Is your car tuned? Is it idling ok, no misfires or rough idle? Worse case scenario, take the car in as Sportstick had mentioned.

Not tuned and idles ok with no misfires or roughness. Coils i don't think have ever been changed, plugs might have I'll have to review the service history. Are coils an easy thing to change?

Originally Posted by Sportstick

I am not sure how you can experience lugging in a parking lot at parking lot speeds, as the car would normally be in 1st or at most 2nd and should not ever experience lugging in those conditions.

For the lugging....mall parking lot (it was empty), rolling mostly in 4th, slowed down a bit too much and tried to speed up again. Terrible feeling lol.

One simple thing to try is when you feel that happening on the highway, immediately change the mode (not just TC on/off) from whatever it is to something else...Comfort to Sport...Sport to Comfort. Any of those. If the symptoms go away, it should start to help with a diagnosis, although I still think you are dealership-bound.

i'll give this a try, i haven't tried changing the modes while it was happening before although it has happened in every mode comfort and up.

Originally Posted by bryan_f22

80mi, wastegate.... turbo next.

try changing your tmap sensors first...

is this a simple change/cheap change?

[hwntime]

Originally Posted by arts711

Not tuned and idles ok with no misfires or roughness. Coils i don't think have ever been changed, plugs might have I'll have to review the service history. Are coils an easy thing to change?



i'll give this a try, i haven't tried changing the modes while it was happening before although it has happened in every mode comfort and up.



is this a simple change/cheap change?

If you've followed regular BMW maintenance, I don't believe your plugs have have been changed as I think they recommend 100k, although most people do their own at 50-60k. And yes, VERY easy to change but always start with the cheapest potential culprit first, which would be the plugs for $120~ish ($20 per plug). Don't go to the dealership because they'll charge you $400-$500.

[arts711]

Originally Posted by hwntime

If you've followed regular BMW maintenance, I don't believe your plugs have have been changed as I think they recommend 100k, although most people do their own at 50-60k. And yes, VERY easy to change but always start with the cheapest potential culprit first, which would be the plugs for $120~ish ($20 per plug). Don't go to the dealership because they'll charge you $400-$500.

I wish it were that simple. These were actually changed out by the dealer back around 60-70k. I'm pretty un-handy so I even ended up getting the maintenance pkg up to 100k.

[delvec03]

Originally Posted by arts711

I wish it were that simple. These were actually changed out by the dealer back around 60-70k. I'm pretty un-handy so I even ended up getting the maintenance pkg up to 100k.

I'm with him. spark plugs. I had a similar issue, though my car is tuned. at high boost I'd get uneven acceleration and a pulsing feeling. BMW should be able to replace your spark plugs with that info. if they weren't gapped properly their life will be significantly shortened.

[arts711]

So after work, I decided to give it a spirited drive home for half and regular the other half and this is what i observed...

In DSC off, sport transmission, it is less noticable, and when i do it's usually as I'm building speed with the engine between 2 and 3ish thousand rpm. Passed that and all the way to red line, there's barely any if at all.

In comfort, standard transmission mode, it's more noticeable as it spends more time in lower revs, that 2 to 4 window.

... Guess i have to drive around like my ass is on fire now

[FaRKle!]

You might want to check if it's related to your transfer case. How's the wear on the front tires compared to the rear ones? I believe there's a fuse you can pull to disable/disengage the transfer case clutches (it will produce a CEL while unplugged).

See our thread about transfer case failures (and failure modes).

[arts711]

Originally Posted by FaRKle!

You might want to check if it's related to your transfer case. How's the wear on the front tires compared to the rear ones? I believe there's a fuse you can pull to disable/disengage the transfer case clutches (it will produce a CEL while unplugged).

See our thread about transfer case failures (and failure modes).

The wear seems to be pretty even but i did notice this morning where the rear pressures were low to the point where they're almost to the point of the front, i wonder if that may have contributed. I'll def check out your link thanks!

[arts711]

Btw, in my research i found this in case anyone else needs it... Looks like a bulletin to diagnose transfer cases in xdrive models.