BMW Z4M S54 - slight hesitation/stutter when you press the accelerator from idle.

Adamw

Adamw

Member
 West Sussex, East Grinstead
As per title, I have a slight hesitation/stutter when you press the accelerator from idle.
Can only describe as a ‘tiny cough/miss’.

I’ve had this since I’ve owned the car (last Oct) but thought maybe normal behaviour of s54 as no other warning lights or misfires through the rev range and it pulls very strong.

I drove a mates e46 m3 and he drove mine and he picked up on this too and his car doesn’t do this.

After a quick google search a few suggestions came up:
* Dirty or aging MAF sensor
* Throttle actuator synchronization
* Coil packs or spark plugs starting to weaken
* Intake air leaks (perished rubber / vacuum leaks)

It does this regardless of the engine temp & as mentioned it’s just off idle / low revs.
There’s no engine light / misfire or any other signs of issues.

I wondered if anyone had experienced anything similar ?

👍🏻
 
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Yeah I have

I started off by replacing the two throttle position sensors- one at the front and one at the rear of the fuel rail

That made a difference and I checked the throttle linkages for smooth operation

However a few months later the stutter returned and threw a code for throttle actuator stiffness

I did a thread on the throttle actuator rebuild as I needed to remove it and had it sent to a chap in Spain who did a proper job

It’s not come back yet
 
Our has always done it, especially if you press the pedal hard.

Replacing the TPS helped for a bit, but it came back. Seems fine if you 'pre-load- the slack on the throttle.
 
There's a big ol' thread on it here.

Are you able to reset the throttle adaptations (e.g. using INPA)? Might not be a permanent fix, but could point you towards one. If you have INPA you can also run a throttle actuation test (although it should be fine/healthy if no errors are being thrown).
 
Thanks all for responses so far.
Sounds like a bit of a common problem then.

It doesn’t affect any other elements of driving but is annoying.
Just wondered if there was a known fix but sounds like it could be a number of things.

I might ask my indi to look next time it’s in, or
otherwise I am contemplating a csl style airbox so wonder if the map would cure 🤔
 
Yeah, think I've had the same since day one. Stab of the throttle at idle sometimes makes it splutter though not checked that since remapped actually. Also get the occasional rev drop when coming back down to idle, like it drops a bit below normal idle revs before settling.

Pretty much everything's been changed that might make a difference, apart from the throttle actuator. Since there's never been any codes and it doesn't make a difference to actual driving or driveability I gave up looking for a solution years ago and just ignore it now.
It's been mapped and carbon airbox as well with no difference so who knows!

I wouldn't get hung up on it tbh. Different ECU(DME) to M3's which probably has something / some part to play in it as you never hear about it on those. Just for info, it's done it since I brought it on 60k miles, now on 117k and it's never got any worse.

I could list all the things I've had changed so you could 'rule' them out, but impossible to know what didn't cure it on mine might cure it on yours hence I'd suggest not worrying about it and put it down as a quirk unless it affects actual driveability/throws codes like bigwinn. Without a code you're kinda peeing in the wind.
 
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Mine is also the same, its annoying at junctions but drive around it by touching the accelerator with a slight amount of rev and it seems to solve it
 
On 13th July 2012, I said this in the other thread:

BMWZ4MC said:
The cams are very aggressive so a slightly lumpy idle is unsurprising. I use only V Power unless I absolutely cannot find a Shell station, and mine is rarely a problem. When I do have any hesitancy, typically it will be in heavy traffic in the rain after a good blast.
Click to expand...
Fourteen years later, I think Andy summarises my experience exactly :

AndyBeech said:
Yeah, think I've had the same since day one. Stab of the throttle at idle sometimes makes it splutter...
Click to expand...
AndyBeech said:
…Also get the occasional rev drop when coming back down to idle, like it drops a bit below normal idle revs before settling.
Click to expand...
I always drive mine with the sports button pressed because it reduces the dead spot at the beginning of the throttle pedal travel. The occasions where I’ve forgotten seem to be associated with a higher likelihood of spluttering and stumbling.
 
Is this a case of S54 kangaroo hopping especially after going into second gear? My S54 hasn’t experienced it (although I have experienced it in other cars) but as I am wary of it I always take care on throttle application in second gear at low revs.
 
CliveN said:
Is this a case of S54 kangaroo hopping especially after going into second gear? My S54 hasn’t experienced it (although I have experienced it in other cars) but as I am wary of it I always take care on throttle application in second gear at low revs.
Click to expand...
Different issue.

It seems to be something to do with the throttle position sensors. Ive heard of success and failure of this but unless you want to rev the car at idle it doesnt effect the car otherwise. Apart from if your napping at lights it can make the engine lurch which is really annoying.

The simple solution is to just have your foot touching the pedal, like 100 revs over idle and it seems to stop the lag.

A clear solution would be useful but had my specialist chasing it for years and havent found the culprit yet.
 
The only one part I would like to see more before and after testing on is the throttle actuator for this. One part that rarely get's changed due to the cost of a new one. Between that and the throttle pedal TPS is pretty much the only part's that's not been changed on mine over the years I can think that would cause an issue.
I still have a partial belief it's a DME/software issue tbh.
 
99% sure the TPS X2 cured mine pre airbox.

Do the knock sensors too while your at it, the one by the bulkhead on mine was definitely out of spec, assume just cooked after years of hammer.
 
Andy, you'd be more than welcome to use my spare actuator for testing, just let me know. Like you though I dont think its the issue, it is of course the exact same part as the e46m3 where this problem does not manifest itself at all.
When I bought my car in 2013 it had this issue, I remember coming into roundabouts or things like that it was horrible.
I'm not sure what fixed mine but I had the engine out for cams, airbox and rod bearings shortly after purchase and it has never reappeared since. I suspect it is most likely the standard map in the mss70 but I have no evidence to support that.
It's pretty nuts that after all these years the 'unmentioned' z4m problem that afflicts so many cars is still unresolved.
 
TomK said:
Andy, you'd be more than welcome to use my spare actuator for testing, just let me know. Like you though I dont think its the issue, it is of course the exact same part as the e46m3 where this problem does not manifest itself at all.
When I bought my car in 2013 it had this issue, I remember coming into roundabouts or things like that it was horrible.
I'm not sure what fixed mine but I had the engine out for cams, airbox and rod bearings shortly after purchase and it has never reappeared since. I suspect it is most likely the standard map in the mss70 but I have no evidence to support that.
It's pretty nuts that after all these years the 'unmentioned' z4m problem that afflicts so many cars is still unresolved.
Click to expand...

Cheers Tom, appreciate it, I'll bear it in mind for the future but not too motivated to fiddle with bits at the moment as it all works well enough that it doesn't bother me at the moment.
It was worse when I bought the car interestingly, revs sometimes dipped enough it would stall which was a lot more annoying. Don't know what was replaced to stop it doing that, possibly the ICV, but hasn't done that for years thankfully, just a few hundred rpm dip these days at worse.

RedUn said:
99% sure the TPS X2 cured mine pre airbox.

Do the knock sensors too while your at it, the one by the bulkhead on mine was definitely out of spec, assume just cooked after years of hammer.
Click to expand...

How'd you know it was out of spec out of interest? Thought knock sensor's either work or they don't?
 
TomK said:
I suspect it is most likely the standard map in the mss70 but I have no evidence to support that.
Click to expand...
Point any LLM at that long thread and it'll conclude that TPS are the most likely culprit, but every TPS replacement comes with an adaptations reset, and there are loads of reported cases of that fixing the problem temporarily on its own. So I think there's a good chance you're right - probably not a hardware issue, but some kind of maladaptation over time by the ECU/DME.

It would be interesting if anybody has replaced TPS and not reset adaptations and that has fixed the issue.
 
AndyBeech said:
The only one part I would like to see more before and after testing on is the throttle actuator for this. One part that rarely get's changed due to the cost of a new one. Between that and the throttle pedal TPS is pretty much the only part's that's not been changed on mine over the years I can think that would cause an issue.
I still have a partial belief it's a DME/software issue tbh.
Click to expand...
I did get some graphical visuals from the guy who rebuild mine- before and after. If I recall it was resistance or similar. I’ll dig it out.
 
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