[SCS55]

I'm new to this engine (daughters car) and noticed even after replacing the engine mounts last week it still has a shake and chug to it. It does this mainly on cold starts and I've seen/felt it to a lesser degree when warm.
To the seasoned N52 folks, do they all shake a little on startup? My old 330ci was shake free, as well as our 335i (N55)

Maintenance completed that I thought would assist a smooth start up...
Both Vanos solenoids (Genuine BMW)
Spark plugs
Air filter
Intake boots up to the throttle body
MAF (Genuine BMW)
Almost everything else has been refreshed including the big task items
OFHG
OPG
Belts
Pulleys
Tensionor
full cooling refresh (water pump, T stat,radiator etc)

I'm unfamiliar with the whole eccentric shaft thing, and I'm guessing that's where I'll be directed. That looks like it's something to be tackled during a VCG job which apparently has been done from the previous owner.

No codes are being thrown, and the Short and Long term fuel trims are spot on.
Thanks in advance.

[cliffschum]

Vehicle Mileage ?

Weak Ignition coils ?

[SCS55]

Originally Posted by cliffschum

Vehicle Mileage ?

Weak Ignition coils ?

109500.
Hadn't thought about the coils?
Good point though.

[e91Owner]

Originally Posted by SCS55

I'm new to this engine (daughters car) and noticed even after replacing the engine mounts last week it still has a shake and chug to it. It does this mainly on cold starts and I've seen/felt it to a lesser degree when warm.
To the seasoned N52 folks, do they all shake a little on startup? My old 330ci was shake free, as well as our 335i (N55)

Maintenance completed that I thought would assist a smooth start up...
Both Vanos solenoids (Genuine BMW)
Spark plugs
Air filter
Intake boots up to the throttle body
MAF (Genuine BMW)
Almost everything else has been refreshed including the big task items
OFHG
OPG
Belts
Pulleys
Tensionor
full cooling refresh (water pump, T stat,radiator etc)

I'm unfamiliar with the whole eccentric shaft thing, and I'm guessing that's where I'll be directed. That looks like it's something to be tackled during a VCG job which apparently has been done from the previous owner.

No codes are being thrown, and the Short and Long term fuel trims are spot on.
Thanks in advance.

Your ESS should be throwing codes if that's the culprit, so I would not go replacing that out of chance. It's expensive, not to mention a PIA to get to. Coils and misfires are going to leave codes as well so that's more than likely not it. I am experiencing a similar problem not a start up but just at general idle and I'm going to try to see if it's the solenoid on the Vanos system being dirty. There are easy to remove and clean so it can't hurt.

When my ESS went bad, the symptoms you describe were the same as you, though.

[SCS55]

Originally Posted by e91Owner

Your ESS should be throwing codes if that's the culprit, so I would not go replacing that out of chance. It's expensive, not to mention a PIA to get to. Coils and misfires are going to leave codes as well so that's more than likely not it. I am experiencing a similar problem not a start up but just at general idle and I'm going to try to see if it's the solenoid on the Vanos system being dirty. There are easy to remove and clean so it can't hurt.

When my ESS went bad, the symptoms you describe were the same as you, though.

Thanks. I'll triple check for codes, although no SES light is on. Other than the problem mentioned during start up, it is super smooth especially after I replaced both solenoids. I may be overreacting but, I was certain it would have the buttery smooth BMW in-line six idle I'm used to even during a cold start.

[e91Owner]

Also, other than the codes, if the eccentric shaft sensor goes, on startup the engine hunts for idle rather than settling around 700. Eventually when the reversion to throttle control catches up, it smooths out. Also, like you describe this is more prevalent during cold starts.

I asked some questions about this a few years ago before replacing mine... reading this post might help you diagnose the sensor if it's not pulling any codes. The code was present without an SES, BTW.

Eccentric shaft sensor fault (2A37) https://www.e90post.com/forums/showthread.php?t=1476059

[SCS55]

Originally Posted by e91Owner

Also, other than the codes, if the eccentric shaft sensor goes, on startup the engine hunts for idle rather than settling around 700. Eventually when the reversion to throttle control catches up, it smooths out. Also, like you describe this is more prevalent during cold starts.

I asked some questions about this a few years ago before replacing mine... reading this post might help you diagnose the sensor if it's not pulling any codes. The code was present without an SES, BTW.

Eccentric shaft sensor fault (2A37) https://www.e90post.com/forums/showthread.php?t=1476059

Good thread thanks. I'm doing research and cross checking my symptoms to see if there's a match.

[kosmokramer]

Any update on this?

[SCS55]

Originally Posted by kosmokramer

Any update on this?

Just checked it. Startup shake still there. AC on or off... no codes either. It's live able but odd, I'll probably tackle the VCG this winter and while I'm in there, I'll address the ESS and the big ticket item, Eccentric Shaft.

[TheBigNate]

I've had my N52 for over 3 years now and it's always had a little bit of a shake on cold starts for the first 10 seconds or so. However, the car starts up instantly and no codes were ever thrown. I would argue that it's normal and after browsing dozens of N52 startups on youtube I came to the conclusion that some cars just do it more than others. I spent hours in the past searching forums trying to find out why my RPM would jump up and down on startup and eventually found out it's most likely a software issue related to fueling that can be fixed by a software update from BMW. Some people found that using ethanol-free fuel fixed their problem and others said replacing the Vanos solenoids fixed their problem but neither of these worked for me. It honestly doesn't bother me anymore because the shaking is very minor and a lot of the time it will start up perfectly with no shaking whatsoever (usually in colder weather).
In terms of the eccentric shaft sensor you mentioned I replaced it a few months ago for preventive maintenance and it didn't change the shaking on startup in the slightest. But do keep in mind that because there isn't any video or audio my shaking might be different than yours.

[SCS55]

Originally Posted by TheBigNate

I've had my N52 for over 3 years now and it's always had a little bit of a shake on cold starts for the first 10 seconds or so. However, the car starts up instantly and no codes were ever thrown. I would argue that it's normal and after browsing dozens of N52 startups on youtube I came to the conclusion that some cars just do it more than others. I spent hours in the past searching forums trying to find out why my RPM would jump up and down on startup and eventually found out it's most likely a software issue related to fueling that can be fixed by a software update from BMW. Some people found that using ethanol-free fuel fixed their problem and others said replacing the Vanos solenoids fixed their problem but neither of these worked for me. It honestly doesn't bother me anymore because the shaking is very minor and a lot of the time it will start up perfectly with no shaking whatsoever (usually in colder weather).
In terms of the eccentric shaft sensor you mentioned I replaced it a few months ago for preventive maintenance and it didn't change the shaking on startup in the slightest. But do keep in mind that because there isn't any video or audio my shaking might be different than yours.

Thanks. Good to know about the ESS as I normally don't throw parts at problems.
I'm pretty much accepting that this shake is inherent in the N52 itself. I'll work on a video.

Until then, I repositioned the car on our driveway today and it's definitely a chug, whirr, whirr rhythm to it that lasts probably 4 to 5 seconds with the final chug almost feeling like the engine is going to stall. My main concern is the condition becoming worse causing a stall and subsequent restart.

[TheBigNate]

Hmm. We might have different symptoms. I never felt like the engine was going to stall being that mine fluctuates around ~200 rpm or so from the desired cold start rpm without any substantial surges.

Here's a video of an average startup for me. Sometimes will be smoother sometimes will be a bit more jolting. Nothing too crazy but I wouldn't call it completely smooth either.

https://1drv.ms/v/s!Ajz7oTgyZSpbil_ROSO8dLq4dNAB

[SCS55]

Originally Posted by TheBigNate

Hmm. We might have different symptoms. I never felt like the engine was going to stall being that mine fluctuates around ~200 rpm or so from the desired cold start rpm without any substantial surges.

Here's a video of an average startup for me. Sometimes will be smoother sometimes will be a bit more jolting. Nothing too crazy but I wouldn't call it completely smooth either.

https://1drv.ms/v/s!Ajz7oTgyZSpbil_ROSO8dLq4dNAB

Missed my cold start opportunity this morning, daughter drove off before I got to it! However, your video is essentially what I'm seeing RPM wise. Yesterday I doubled checked for codes and found none. Since I have pretty much refreshed everything on the car and aside from this cold start shake, the engine is running perfect. I'm chalking it up to a N52 characteristic.
I guess I'm just spoiled by my F80's S55 which is so damn smooth, sometimes at stop lights I can't tell if it's on or off. But I digress.

As mentioned earlier, I'm doing the valve cover gasket this winter and refreshing those associated items and we'll see what happens.
Thx

[SCS55]

Update...Just completed the valve cover gasket job. While I was in there I replaced the Eccentric Shaft Sensor, it's gasket, the Valvetronic gasket, and a new oil filler cap.
Everything went well.
After starting the engine the cold start shake was there but very minimal compared to before.

A note aside, my valve cover leak rapidly increased over the last month or so to the point where I was starting to get a vacuum leak which definitely didn't help matters during a cold start. My fuel trims were spot on today especially the LTFT's.

[thomas1097]

Originally Posted by SCS55

I'm new to this engine (daughters car) and noticed even after replacing the engine mounts last week it still has a shake and chug to it. It does this mainly on cold starts and I've seen/felt it to a lesser degree when warm.
To the seasoned N52 folks, do they all shake a little on startup? My old 330ci was shake free, as well as our 335i (N55)

Maintenance completed that I thought would assist a smooth start up...
Both Vanos solenoids (Genuine BMW)
Spark plugs
Air filter
Intake boots up to the throttle body
MAF (Genuine BMW)
Almost everything else has been refreshed including the big task items
OFHG
OPG
Belts
Pulleys
Tensionor
full cooling refresh (water pump, T stat,radiator etc)

I'm unfamiliar with the whole eccentric shaft thing, and I'm guessing that's where I'll be directed. That looks like it's something to be tackled during a VCG job which apparently has been done from the previous owner.

No codes are being thrown, and the Short and Long term fuel trims are spot on.
Thanks in advance.

This is most likely a timing issue with your VANOS unit itself. It may need to be replaced. If it's a rough idle on cold start and goes away when the engine reaches temperature then it's definitely the VANOS unit. Happened to my N51, they're basically the same engine. Thank god for that SULEV warranty or it would have costed me a good $5-6k to repair according to the dealer.

[SCS55]

Originally Posted by thomas1097

This is most likely a timing issue with your VANOS unit itself. It may need to be replaced. If it's a rough idle on cold start and goes away when the engine reaches temperature then it's definitely the VANOS unit. Happened to my N51, they're basically the same engine. Thank god for that SULEV warranty or it would have costed me a good $5-6k to repair according to the dealer.

Wasn't the Vanos at all. Both new Genuine BMW intake and exhaust solenoids at $140.00 each (ouch!) took care of that.
It was a worn diaphragm/spring in the VC built in CCV. Swapped the VC and also replaced the rear crankcase vent hose which connects to the rear VC.
Buttery smooth now on any start condition cold or hot.

[e91Owner]

Terrible design