[JoshApple]

So I'm having this really odd problem with my 335i.

It's been happening for quite a while but basically I'm having some weird stuttering and jumpiness when I left off the gas at or around 90mph. It only happens at around this speed and will also happen if I'm trying to cruise in this rpm range with the gas pedal.

It's as if my car is jumping back and forth really slightly or something. Engine rpms cut down about 50-100 and jump back up quickly and thus feels like stuttering.

I recently tuned to MHD 2+ but this WAS happening prior so it's not related to the tune.

https://datazap.me/u/japple7/stutter...&data=3-20

(This includes two logs)

I ran a few logs that you guys can take a look at but what to look out for:

1. Accel pedal position- when it goes up that's when I'm trying to get to around 90 mph and then I let off or ease up to try and get this effect to happen.

2. STFT's - they appear to jump super high then super low while this is happening

3. AFR's - also super high when this is happening

Overall, my car just feels unstable when I'm cruising at these speeds or decelerating around this speed

My guess is o2 sensors but feel free to give your input

Thanks in advance

[NoGuru]

I think you might be correct with the O2's. If its not that then it may be the injectors.
Everything else looks good.

O2's are pretty cheap so I would start with them.

When I first read this I was like "where could someone do 90mph" then I see you live near US23 and it all makes sense now

[JoshApple]

Originally Posted by NoGuru

I think you might be correct with the O2's. If its not that then it may be the injectors.
Everything else looks good.

O2's are pretty cheap so I would start with them.

When I first read this I was like "where could someone do 90mph" then I see you live near US23 and it all makes sense now

Will do, thanks for the reply I appreciate it

And hahah yes and I-96

Too bad the roads here are awful so it's not even enjoyable 😒

[NoGuru]

No problem, post the results after changing the O2's.

[mweisdorfer]

Originally Posted by JoshApple

So I'm having this really odd problem with my 335i.

It's been happening for quite a while but basically I'm having some weird stuttering and jumpiness when I left off the gas at or around 90mph. It only happens at around this speed and will also happen if I'm trying to cruise in this rpm range with the gas pedal.

It's as if my car is jumping back and forth really slightly or something. Engine rpms cut down about 50-100 and jump back up quickly and thus feels like stuttering.

I recently tuned to MHD 2+ but this WAS happening prior so it's not related to the tune.

https://datazap.me/u/japple7/stutter...&data=3-20

(This includes two logs)

I ran a few logs that you guys can take a look at but what to look out for:

1. Accel pedal position- when it goes up that's when I'm trying to get to around 90 mph and then I let off or ease up to try and get this effect to happen.

2. STFT's - they appear to jump super high then super low while this is happening

3. AFR's - also super high when this is happening

Overall, my car just feels unstable when I'm cruising at these speeds or decelerating around this speed

My guess is o2 sensors but feel free to give your input

Thanks in advance

What are your codes?

[JoshApple]

Originally Posted by mweisdorfer

What are your codes?

None

[mweisdorfer]

Originally Posted by JoshApple

None

You are using ISTA or INPA?

[JoshApple]

Originally Posted by mweisdorfer

You are using ISTA or INPA?

Inpa and MHD code reader, never gives me any codes it just happens

[mweisdorfer]

Originally Posted by JoshApple

Inpa and MHD code reader, never gives me any codes it just happens

AFR's should read around 14.7 and shouldn't jump a whole lot. STFT's should read around 0 but shouldn't really be over over +/- 8%.

[JoshApple]

Originally Posted by mweisdorfer

AFR's should read around 14.7 and shouldn't jump a whole lot. STFT's should read around 0 but shouldn't really be over over +/- 8%.

Lolol check out those logs and see it's not that

[mweisdorfer]

Originally Posted by JoshApple

Lolol check out those logs and see it's not that

I'd start by replacing all 4 O2 sensors w/ Bosch. Get them at FCP for the lifetime warranty. It's gonna run you $400.00…. 🤬 reset the adaptations after install for the lambda's.

If that doesn't fix it, replace the plugs. (Look at your plugs & see if they are burnt or black)

If not, it's your injectors most likely.

I'm surprised you are not getting any codes.

[Dave92N54]

I'm not surprised in the slightest that this isn't throwing codes. Looks like almost every other case of oscillating AFRs/trims, and they almost never get any codes. I'm on mobile so it's pretty hard to look at but appears to me, the surging happens when you're at a high manifold vacuum (close to -10psi or so), which is the case for myself and others i've seen. Though mine seems to only happen with very low throttle applied, does nothing if you completely let off or get on the throttle a little more.

I agree with all the suggestions here, hopefully they work for you. So far, they have not for me. I have all new plugs, coils, injectors, vacuum lines, all 4 O2s, cleaned vanos solenoids, new boost solenoids, and walnut blast. The only things I have left that seem to solve this issue are the MAP on the manifold, the vanos solenoids (though I never get vanos codes so doubt they're the issue), and the throttle body itself. Unfortunately with no codes, and not wanting to just throw hundreds and hundreds of dollars at it, it's hard to figure out what to do.

Within the last month i've started getting puffs of smoke when coming to a stop (only sometimes too). I currently have a set of RBs on order. I've begun to wonder if in my case, small amounts of oil are making it through the turbo seals at high vacuum and are throwing off the AFRs, causing trims to go haywire. Car cruises completely fine at any manifold vacuum greater than approximately-10psi, pulls perfectly and all WOT logs look great. I actually have several logs of the surging if you'd like to compare. This issue has been a real pain in my ass for awhile.

[whyzee125]

I'm fighting the same thing and have replaced almost the same things as Dave above me.

New:

front & rear o2's
Eldor coils
NGK spark plugs gapped at .018
new OEM vanos solenoids
index 12 injectors from a few years ago
hpfp is fine

Reset adaptations made it drive wonderful for about 500 miles then came back. Very frustrated.

[Dave92N54]

Originally Posted by whyzee125

I'm fighting the same thing and have replaced almost the same things as Dave above me.

New:

front & rear o2's
Eldor coils
NGK spark plugs gapped at .018
new OEM vanos solenoids
index 12 injectors from a few years ago
hpfp is fine

Reset adaptations made it drive wonderful for about 500 miles then came back. Very frustrated.

After reading another on going thread, i'm leaning towards the throttle body. OP on that post stated he did a walnut blast and replaced his TB and it stopped, also said his old TB had a rattle if you shook it. Well, had mine off about a week ago to do a walnut blast and sure enough I noticed a rattle when I moved the TB.

N54 surging around 3000rpm constant throttle input https://www.e90post.com/forums/showthread.php?t=1847644

[whyzee125]

Originally Posted by Dave92N54

After reading another on going thread, i'm leaning towards the throttle body. OP on that post stated he did a walnut blast and replaced his TB and it stopped, also said his old TB had a rattle if you shook it. Well, had mine off about a week ago to do a walnut blast and sure enough I noticed a rattle when I moved the TB.

N54 surging around 3000rpm constant throttle input https://www.e90post.com/forums/showthread.php?t=1847644

This is fantastic news, I'll try that on mine too. Adam LZ on youtube said he was chasing some funky issues that a shop ended up diagnosing (correctly) as his throttle body, but he never said what the symptoms were. Thank you!

[mweisdorfer]

Originally Posted by whyzee125

I'm fighting the same thing and have replaced almost the same things as Dave above me.

New:

front & rear o2's
Eldor coils
NGK spark plugs gapped at .018
new OEM vanos solenoids
index 12 injectors from a few years ago
hpfp is fine

Reset adaptations made it drive wonderful for about 500 miles then came back. Very frustrated.

Why .018 gap?

[mweisdorfer]

Originally Posted by Dave92N54

After reading another on going thread, i'm leaning towards the throttle body. OP on that post stated he did a walnut blast and replaced his TB and it stopped, also said his old TB had a rattle if you shook it. Well, had mine off about a week ago to do a walnut blast and sure enough I noticed a rattle when I moved the TB.

N54 surging around 3000rpm constant throttle input https://www.e90post.com/forums/showthread.php?t=1847644

I replaced my Throttle Body back in May. It had 179,000 miles on it. I got lots of codes for it when it went and the car went into limb mode.

[Dave92N54]

Originally Posted by mweisdorfer

I replaced my Throttle Body back in May. It had 179,000 miles on it. I got lots of codes for it when it went and the car went into limb mode.

I don't doubt totally throttle failure would throw a shitload of codes, but there are certainly several failure modes for almost every part. Hell, when my LPFP sensor was bad, nobody could figure it out because it didn't fail in either of the typical manners that it does (being pegged at 0psi or 72, it just read like 20psi low all the time, so I replaced the LPFP and FPR first)

I have spoken with several individuals who all never got throttle codes, and had the surging at low throttle input solved by replacing the throttle body. I've even read of individuals who had it slowly fail for an entire year until it finally threw a code for the throttle.