[naCAnItihS]

Update 4/13/20

The LPFP was acting up and causing inconsistent fuel pressure causing an occasional dip in pressure for the HPFP due to low fuel volume. Replaced the LPFP with a Walbro 450 using the DIY method from STUCK. And it runs so much better now.

Editing this 10/9/19.

Ok still having the idle hesitations which are more apparent when its cold. Cleaning the VANOS didn't solve my issue. I have also replaced the plugs with the Bosch double platinum plugs. The coil packs were replaced less than a year ago. Still no codes and the car fires right up (no long cranks).

I brought it to a local BMW specialist shop near my work and they did some diagnosis. He did a smoke test, so no vac leaks. He then said he was checking the fuel pressure and also hooked up an actual gauge to the pump. When it was hooked up to the system he said he did get a low fuel pressure notification, however the pressure was still within the spec. He also mentioned that he noticed the fuel pressure was fluctuating (i dont know by how much). The car is MHD Stage 2+ and he asked me to return it to stock so that he could confirm the tune wasn't doing anything weird to the fuel system. I haven't brought it back to him yet but I don't believe the tune would affect anything as it did this before I even modified the vehicle.

Just curious if you guys think it may be HPFP or LPFP related? I plan on doing the work myself I just brought it to a shop for diagnosis because I was at a loss and don't have the proper BMW test equipment.


Old:

Hello,

So I am new to the N55 and have only had my car (2011 535i M-Sport) for about a month an a half. I am not newb to cars or working on them as I have built many Subarus Nissan etc. Also I had 2011 335D a few years back.

Anyway to my point. I've seen a lot of posts about idle shudders and hesitation with these but could never really find the answer. My car has the shudder at idle, to an annoying point, but seems fine in any other RPM range. I've seen a lot of people saying replace coil packs, plugs, Chevron Techron fuel system cleaner. The new plugs and coils were done a few months before I bought the car (have receipts from the BMW performance shop that did the work. And I have run the Techron cleaner through the system.

What I have noticed (which I haven't seen in other posts) is that the idle shudder occurs mainly in Comfort and Normal modes. When I put the car in Sport mode about 85% of the shakes go away and the engine seems a lot smoother. It still will have an occasional hiccup but it is not nearly as noticeable. I know that the Sport mode configures the suspension and does something to the engine as there is an option for just suspension or both when sport mode is configured.

Does sport mode change the VANOS settings? I don't have any codes or shadow codes based on the MHD scan. Also speaking of MHD the idle hiccups seemed to get worse once I flashed the system Stage 2. Stock I could notice them but after the flash it became more apparent.

Do you guys think cleaning the VANOS will help or should I replace them? The car has 86k miles on it. Any other ideas? I really have no interest in bringing it to the dealer if I don't have to.

Thanks

-JD

[Shieldze1025]

Sounds normal to me. Sport mode increases the throttle a little bit so you're just lifting your RPMs more. I have BM3 but mine acts the same - Comfort mode is loud at idle and Sport is quieter. It's definitely not a shutter and not annoying by any means, though.

I know what you mean about the sputtering - I only notice it when the engine is cold, and it's just a little blip here and there. Again, nothing major at all.

Just wondering - Do you have a wastegate rattle at all? Mine is pretty bad, I could see this annoying you, but it's more of a rattle sound then a vibrating shutter, if that makes sense.

[naCAnItihS]

Originally Posted by Shieldze1025

Sounds normal to me. Sport mode increases the throttle a little bit so you're just lifting your RPMs more. I have BM3 but mine acts the same - Comfort mode is loud at idle and Sport is quieter. It's definitely not a shutter and not annoying by any means, though.

I know what you mean about the sputtering - I only notice it when the engine is cold, and it's just a little blip here and there. Again, nothing major at all.

Just wondering - Do you have a wastegate rattle at all? Mine is pretty bad, I could see this annoying you, but it's more of a rattle sound then a vibrating shutter, if that makes sense.

No wastegate rattle that I am aware of right now. The idle shutter is not really subtle as you are describing. If it were a blip here and there then it prob wouldn't bother me but it is constant. Also, I don't notice a change in sound between the modes. To be honest it kind of feels like a miss or timing is off. Reminds me of an older car, like I need to turn the distributor and give it an extra degree of timing or something. This is why I think it may be Vanos related. I planned on cleaning them this past weekend but with this heatwave we just had, the Boat sounded like more fun haha.

[baconbits]

Bone stock 2012 535i xdrive here. I've got the slight shudder/shake at idle too but it's only on cold starts and goes away after any kind of throttle application.

A friend has an E60 535 and said he had something far worse (like LS V8 cam chop shudder) when he really needed his intake valves walnut blasted. I recently had my VC and OFH gaskets done and my indy mechanic said my valves were remarkably clean for 94k... "just a thin film of carbon, no gunk or buildup."

He didn't even notice the shudder/shake so he told me to stop worrying about it considering there are no codes to go with it either.

[Shieldze1025]

Originally Posted by baconbits

Bone stock 2012 535i xdrive here. I've got the slight shudder/shake at idle too but it's only on cold starts and goes away after any kind of throttle application.

A friend has an E60 535 and said he had something far worse (like LS V8 cam chop shudder) when he really needed his intake valves walnut blasted. I recently had my VC and OFH gaskets done and my indy mechanic said my valves were remarkably clean for 94k... "just a thin film of carbon, no gunk or buildup."

He didn't even notice the shudder/shake so he told me to stop worrying about it considering there are no codes to go with it either.

So the E60 had an N54 which is notorious for carbon buildup. Walnut Blasting is a must.

But on the N55 it's not a problem at all. Good to hear you didn't need it at 94k

[naCAnItihS]

Everything I've read about the N55 regarding walnut blast is that it is very rarely needed. The BMW Performance shop I bought the car from did the Oil-Housing gasket and the Valve cover gasket. I would only assume they would have said something to the PO about it needing a clean and/or would have done it if necessary.

So I did get around to changing the oil (Liquid Moly 5W-30) and cleaning the VANOS solenoids this past weekend. The engine def seems to run smoother overall but still has that shake randomly at idle. It still stumbles a little at cold start and then kind of random when hot idle. Sometimes its smooth other times it is hiccuping /lurchy.

Even though I have receipts from 11/30/2018 that the Plugs (NGK) /Coils (OEM) were changed. I bought new ones again but the Bosch ZR5TPP33 and Delphi Coils, which I plan to install this week. Hopefully that will change things? If it doesn't I'm at a loss on what to do next.

[paul223]

My engine gets this occasional shudder/shake on cold start, I think it only happens on cool/cold mornings. It is normal I believe. Engine has PS2 installed.

[naCAnItihS]

I'm more concerned with the HOT idle shaking. It makes me hate this damn car

Different note I still wont accept that the Cold shaking is normal on a $60k vehicle when no other vehicle does this..

[Force2013]

I had the same problem, it was a leaking injector. The car worked fine at all RPM range but would shake in idle sometimes. You could feel the shake but could not see it on the gage.

Long story short i bought a new injector and coded it in and the car is running great again.

Easiest way to see if it is the injector is 1 to listen to the engine to see if you hear a tick or hiss sound comming from the cylinder area or use ISTA D to do a rough running test to see if a cylinder is running bad.

[Shieldze1025]

Originally Posted by naCAnItihS

I'm more concerned with the HOT idle shaking. It makes me hate this damn car

Different note I still wont accept that the Cold shaking is normal on a $60k vehicle when no other vehicle does this..

Definitely sounds like you have something other than the "normal" shaking at startup. It's not a problem at all and really isn't shaking, more so the normal sound of a cold engine starting up for the first 15 seconds.

[jonobro]

Originally Posted by Force2013

I had the same problem, it was a leaking injector. The car worked fine at all RPM range but would shake in idle sometimes. You could feel the shake but could not see it on the gage.

Long story short i bought a new injector and coded it in and the car is running great again.

Easiest way to see if it is the injector is 1 to listen to the engine to see if you hear a tick or hiss sound comming from the cylinder area or use ISTA D to do a rough running test to see if a cylinder is running bad.

How could you use INSTA to test if a injector is bad

[naCAnItihS]

bump for more info added to the original post

[jooobi3]

Originally Posted by naCAnItihS

bump for more info added to the original post

Sounds normal to me. Mine does the same thing I have a 2011 535ix with Mhd stage 2 plus.

[Bav@Heart]

I too think it is normal. My F15 X5 always has done it, however, my F10 535i did not. I assumed it was because of pwg vs ewg. Recently my F10 started doing this too and it all started after updating my DME. No codes present. This must be some sort of BMW adaptation process that causes it. I wouldn't worry too much about it.

[Gjohnson7]

Well, just to add to the list. I have a 2011 535i that also has the rough idle on cold starts. I've only owned the car for about 2 months, but I recently replaced the gaskets, spark plugs and cleaned the Vanos. I inspected the intake valves while I was replacing the gaskets and they didn't look too bad, but now I'm regretting not cleaning. My F10 has about 129k miles.

[naCAnItihS]

I ended up bringing it to a shop a little while ago and the guy said that he did find some low fuel pressure warnings, but nothing that triggered a CEL or any warnings. Also nothing that MHD would pick up.. He did mention that the fuel pressure was fluctuating and that he hooked up a gauge to the LPFP and said it was inconsistent.

I then checked the fuel rail pressure via the Torque Pro app (not ideal but I already had it).

I noticed that when it did the hiccup the rail pressure would drop from 800ish psi to like 650 but would then recover. Based on the shop saying the LPFP pressure was inconsistent I decided to just upgrade the LPFP to a Walbro 450 since it was the cheaper of the 2 pumps and I wanted to run an E85 blend anyway. I did the DIY methond that STUCK made a while ago. Cost about $110 and about an 1.5-2 hrs of my time. Pretty simple actually, much easier than the other F series install that Fuel-It posted.

Anyway it has seemingly fixed my issue and my fuel pressure is staying consistent and its running way smoother. Haven't noticed that rough idle yet!

[beebon619]

Originally Posted by naCAnItihS

I ended up bringing it to a shop a little while ago and the guy said that he did find some low fuel pressure warnings, but nothing that triggered a CEL or any warnings. Also nothing that MHD would pick up.. He did mention that the fuel pressure was fluctuating and that he hooked up a gauge to the LPFP and said it was inconsistent.

I then checked the fuel rail pressure via the Torque Pro app (not ideal but I already had it).

I noticed that when it did the hiccup the rail pressure would drop from 800ish psi to like 650 but would then recover. Based on the shop saying the LPFP pressure was inconsistent I decided to just upgrade the LPFP to a Walbro 450 since it was the cheaper of the 2 pumps and I wanted to run an E85 blend anyway. I did the DIY methond that STUCK made a while ago. Cost about $110 and about an 1.5-2 hrs of my time. Pretty simple actually, much easier than the other F series install that Fuel-It posted.

Anyway it has seemingly fixed my issue and my fuel pressure is staying consistent and its running way smoother. Haven't noticed that rough idle yet!

My 2012 535i is having the same issue. Warmed up, still idles at a stop light or when stopped in 'normal, eco pro, comfort or comfort+'. Sport and sports+ somewhat helps out the idle issue.