N55 Idle shudder / shake. HPFP, LPFP? Injector?

naCAnItihS · 07-18-2019, 09:20 AM

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, (Adding this to the F30 forum since I haven't heard anything on the F10 forum)

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

Polo08816 · 07-18-2019, 09:46 AM

Does a drivetrain malfunction come up? If so, I would read the codes. The shudder could be from a whole host of issues... PCV, sensors (camshaft or crankshaft), VANOS solenoids, ignition issues (plug and coils), fueling issues (injectors or HPFP), etc.

naCAnItihS · 07-18-2019, 11:00 AM

No drivetrain malfunction. Occasionally I get a DSC Malfunction that pops up. But once I click the ok button it goes away and there aren't any warnings left. I have the electronic suspension. I would hope that has nothing to do with the engine.

I do plan on cleaning the VANOS, changing the plugs and oil this weekend. I'll see what happens after only cleaning the vanos first.

Polo08816 · 07-18-2019, 02:29 PM

Quote:

Originally Posted by naCAnItihS

No drivetrain malfunction. Occasionally I get a DSC Malfunction that pops up. But once I click the ok button it goes away and there aren't any warnings left. I have the electronic suspension. I would hope that has nothing to do with the engine.

I do plan on cleaning the VANOS, changing the plugs and oil this weekend. I'll see what happens after only cleaning the vanos first.

How do you "clean the VANOS"?

Ristau · 07-18-2019, 05:03 PM

Quote:

Originally Posted by naCAnItihS

No drivetrain malfunction. Occasionally I get a DSC Malfunction that pops up. But once I click the ok button it goes away and there aren't any warnings left. I have the electronic suspension. I would hope that has nothing to do with the engine.

I do plan on cleaning the VANOS, changing the plugs and oil this weekend. I'll see what happens after only cleaning the vanos first.

Please let us know how this goes

I'm in pretty much the exact same boat.

naCAnItihS · 07-18-2019, 11:18 PM

Quote:

Originally Posted by Polo08816

How do you "clean the VANOS"?

You pull the solenoids out of the front of the motor and spray them with carb cleaner or brake clean, inside and out. Gets any gunk build up out of there. They have very fine screens that can clog up etc. Should t tak too long. Just looks tight to get at them.

Here is a youtube vid

https://youtu.be/FzDF4BqDS2Q

Polo08816 · 07-19-2019, 08:11 AM

Quote:

Originally Posted by naCAnItihS

You pull the solenoids out of the front of the motor and spray them with carb cleaner or brake clean, inside and out. Gets any gunk build up out of there. They have very fine screens that can clog up etc. Should t tak too long. Just looks tight to get at them.

Here is a youtube vid

https://youtu.be/FzDF4BqDS2Q

Gotcha. I was actually just going to replace them this weekend. I have 116k on my car and don't want to lose a track weekend for some sensor failures.

naCAnItihS · 07-19-2019, 09:56 AM

Quote:

Originally Posted by Polo08816

Gotcha. I was actually just going to replace them this weekend. I have 116k on my car and don't want to lose a track weekend for some sensor failures.

Ya I figured I would try cleaning them first before spending money on new ones. My car is just a DD so its worth the attempt to do it for free first. If I need to get new then I will and down time doesn't matter as I have other vehicles.

naCAnItihS · 08-06-2019, 06:00 PM

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.

Russbmw · 08-12-2019, 08:03 AM

At that kind of mileage I'd recommend having the intake walnut blasted.

My old e92 335i (N54) had a slight hiccup/stutter that made itself apparent at 70-80mph constant speed - it'd feel like a misfire. No fault codes or anything.

After the intake cleaning it felt like a new car....literally.

exE36M3 · 08-12-2019, 09:25 AM

Quote:

Originally Posted by Russbmw

At that kind of mileage I'd recommend having the intake walnut blasted.

My old e92 335i (N54) had a slight hiccup/stutter that made itself apparent at 70-80mph constant speed - it'd feel like a misfire. No fault codes or anything.

After the intake cleaning it felt like a new car....literally.

Yep, this. Google "Walnut Blast and Intake and BMW N55".
If your symptoms follow the patterns of your search results, this is worth looking into it.

arhoads335i · 08-12-2019, 06:34 PM

Personal I would think fuel related. Can you monitor your hpfp? Could be a bad injector also.
Do you know if the valvetronic motor has ever been replaced?
What code scanner are you using?

naCAnItihS · 08-13-2019, 09:59 AM

Quote:

Originally Posted by percychow

Yep, this. Google "Walnut Blast and Intake and BMW N55".
If your symptoms follow the patterns of your search results, this is worth looking into it.

Everything I've read about the N55 is that the walnut blasting is not really necessary. The N54 needed it a lot.

Quote:

Originally Posted by arhoads335i

Personal I would think fuel related. Can you monitor your hpfp? Could be a bad injector also.
Do you know if the valvetronic motor has ever been replaced?
What code scanner are you using?

I have MHD and the bimmergeeks Pro cable. I didn't buy the monitoring part but I could if needed. Don't know if the valvetronic motor has been replaced. I have receipts for a few things but that wasn't one of them. Whats a good way to monitor the HPFP and how would I know if it is bad or an injector is bad?

Thanks

-JD

naCAnItihS · 10-09-2019, 02:33 PM

bump for more info added to original post

DreamerJoe · 10-09-2019, 04:46 PM

maybe try some injector cleaner and hope it's that simple? and since you already have mhd, get the monitor license too if you don't already, and do a manual log while idling and see if you can get a log of the stutter. make sure you check as many monitoring modules as possible, iirc not all are checked from the start.

Polo08816 · 10-10-2019, 10:08 AM

Quote:

Originally Posted by DreamerJoe

maybe try some injector cleaner and hope it's that simple? and since you already have mhd, get the monitor license too if you don't already, and do a manual log while idling and see if you can get a log of the stutter. make sure you check as many monitoring modules as possible, iirc not all are checked from the start.

BMW ISTA should tell you exactly what the problem is.

I had this problem and one of the symptoms was white smoke (that smelled like gas) out the exhaust. It was a stuck open injector in cylinder 6.

With 115k miles on the odometer, I ended up replacing the LPFP, HPFP and all 6 injectors in my home garage.

naCAnItihS · 04-13-2020, 09:55 AM

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!

thejeremyman9 · 04-13-2020, 12:35 PM

Quote:

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!

Any concerns with stock EKP with upgraded LPFP? Or no since you are not running PI?

naCAnItihS · 04-14-2020, 01:32 PM

Quote:

Originally Posted by thejeremyman9

Any concerns with stock EKP with upgraded LPFP? Or no since you are not running PI?

I'm not too concerned right now as I am only running 1 pump and its still in the mid 50*F right now. Have only really heard of issues when it is hot outside since the EKP likes to overheat.

I will most likely add a heat sink to the case or a small CPU fan to keep it nice and cool.

Check out this thread:
https://www.bimmerfest.com/forums/sh....php?t=1316911

cthompson · 10-15-2021, 04:19 PM

Hey everyone I am having the same issue as the author stated I was just curious if anyone had the write up for upgrading the LPFP by STUCK? My car recently had HPFP replaced with papers and the previous owner said he just replaced plugs and coils. Thanks or if the original author naCAnItihS has the write up that he could share?

thejeremyman9 · 10-15-2021, 04:24 PM

Quote:

Originally Posted by cthompson

Hey everyone I am having the same issue as the author stated I was just curious if anyone had the write up for upgrading the LPFP by STUCK? My car recently had HPFP replaced with papers and the previous owner said he just replaced plugs and coils. Thanks or if the original author naCAnItihS has the write up that he could share?

Are you just asking how to replace the LPFP? I believe there are videos on YouTube?

n55david · 10-15-2021, 04:32 PM

Quote:

Originally Posted by cthompson

Hey everyone I am having the same issue as the author stated I was just curious if anyone had the write up for upgrading the LPFP by STUCK? My car recently had HPFP replaced with papers and the previous owner said he just replaced plugs and coils. Thanks or if the original author naCAnItihS has the write up that he could share?

there are a ton of videos on swapping the lpfp.. I've done it a few times now

07-18-2019, 09:20 AM	#1
naCAnItihS Private First Class 27 Rep 137 Posts Drives: 2011 BMW 535i MSport Join Date: Jun 2015 Location: Nashua, NH iTrader: (0)	N55 Idle shudder / shake. HPFP, LPFP? Injector? 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, (Adding this to the F30 forum since I haven't heard anything on the F10 forum) 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 Last edited by naCAnItihS; 04-13-2020 at 10:23 AM..
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07-18-2019, 09:46 AM	#2
Polo08816 Brigadier General 1610 Rep 3,947 Posts Drives: 2014 335i M Sport Join Date: Sep 2010 Location: MD iTrader: (0)	Does a drivetrain malfunction come up? If so, I would read the codes. The shudder could be from a whole host of issues... PCV, sensors (camshaft or crankshaft), VANOS solenoids, ignition issues (plug and coils), fueling issues (injectors or HPFP), etc.
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07-18-2019, 11:00 AM	#3
naCAnItihS Private First Class 27 Rep 137 Posts Drives: 2011 BMW 535i MSport Join Date: Jun 2015 Location: Nashua, NH iTrader: (0)	No drivetrain malfunction. Occasionally I get a DSC Malfunction that pops up. But once I click the ok button it goes away and there aren't any warnings left. I have the electronic suspension. I would hope that has nothing to do with the engine. I do plan on cleaning the VANOS, changing the plugs and oil this weekend. I'll see what happens after only cleaning the vanos first.
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08-06-2019, 06:00 PM	#9
naCAnItihS Private First Class 27 Rep 137 Posts Drives: 2011 BMW 535i MSport Join Date: Jun 2015 Location: Nashua, NH iTrader: (0)	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.
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08-12-2019, 08:03 AM	#10
Russbmw Colonel 680 Rep 2,444 Posts Drives: 2018 630iGT sport Join Date: Aug 2013 Location: Caloundra, Australia iTrader: (0) Garage List 2014 BMW 640i [0.00] 2014 BMW 530d GT [0.00] 2017 Kawasaki Z1000SX [0.00]	At that kind of mileage I'd recommend having the intake walnut blasted. My old e92 335i (N54) had a slight hiccup/stutter that made itself apparent at 70-80mph constant speed - it'd feel like a misfire. No fault codes or anything. After the intake cleaning it felt like a new car....literally. __________________
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08-12-2019, 06:34 PM	#12
arhoads335i Captain 180 Rep 772 Posts Drives: 2015 435i grand coupe xdrive Join Date: Jan 2017 Location: Philadelphia, PA iTrader: (3) Garage List 2008 BMW 128I [0.00]	Personal I would think fuel related. Can you monitor your hpfp? Could be a bad injector also. Do you know if the valvetronic motor has ever been replaced? What code scanner are you using? __________________ 2015 435i grand coupe xdrvie (current) 2006 F250 powerstoke CCSB (current) 2014 M235i Black on Red (SOLD) / 08 e90 335i MT Pure Stage 2 High flow (SOLD) 08 128i 6MT (SOLD) / 08 335i 6MT Pure stage 1 (SOLD)
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10-09-2019, 02:33 PM	#14
naCAnItihS Private First Class 27 Rep 137 Posts Drives: 2011 BMW 535i MSport Join Date: Jun 2015 Location: Nashua, NH iTrader: (0)	bump for more info added to original post
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10-09-2019, 04:46 PM	#15
DreamerJoe Captain 242 Rep 764 Posts Drives: 2017 340i M.G. w red interior Join Date: Dec 2018 Location: SoCal iTrader: (0)	maybe try some injector cleaner and hope it's that simple? and since you already have mhd, get the monitor license too if you don't already, and do a manual log while idling and see if you can get a log of the stutter. make sure you check as many monitoring modules as possible, iirc not all are checked from the start. __________________ MG F30 M-Sport 6mt FBO w/ MHD stage 2 plus (PWG), ST XA Coilovers, 19" VMR V804.
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04-13-2020, 09:55 AM	#17
naCAnItihS Private First Class 27 Rep 137 Posts Drives: 2011 BMW 535i MSport Join Date: Jun 2015 Location: Nashua, NH iTrader: (0)	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!
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10-15-2021, 04:19 PM	#20
cthompson Registered 0 Rep 1 Posts Drives: 2012 BMW X3 35i Join Date: Oct 2021 Location: Colorado iTrader: (0)	Same issue Hey everyone I am having the same issue as the author stated I was just curious if anyone had the write up for upgrading the LPFP by STUCK? My car recently had HPFP replaced with papers and the previous owner said he just replaced plugs and coils. Thanks or if the original author naCAnItihS has the write up that he could share? Last edited by cthompson; 10-15-2021 at 04:22 PM.. Reason: Forgot a piece of info.
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