[alexwhittemore]

Daan - you've been having this issue since 2016 and haven't ghostridden this car into a lake yet? You're a strong person.

I went back and looked at your symptoms - they sound IDENTICAL to mine, up to and including "less of a problem in the cold season."

The only hitch is - your mods list includes "short shifter" - am I to infer you have a manual transmission? That'd be a HUGE bummer, because I know two things:

1) ATF won't last much longer than 100k miles - it's not even rated to IN THIS APPLICATION, don't let the "lifetime fluid" bullshit confuse you. "Lifetime" is 8 years or 100k miles, per the goddamn transmission datasheet

2) Failing ATF looks EXACTLY like this. Works great cold, starts to lose viscosity once warm and fucks up shift timing and power transfer. Mostly a problem at high differential input/output speeds, so you don't really have an issue once the car is /moving/ - just around takeoff.

[DaanBMW]

Originally Posted by alexwhittemore

Daan - you've been having this issue since 2016 and haven't ghostridden this car into a lake yet? You're a strong person.

I went back and looked at your symptoms - they sound IDENTICAL to mine, up to and including "less of a problem in the cold season."

The only hitch is - your mods list includes "short shifter" - am I to infer you have a manual transmission? That'd be a HUGE bummer, because I know two things:

1) ATF won't last much longer than 100k miles - it's not even rated to IN THIS APPLICATION, don't let the "lifetime fluid" bullshit confuse you. "Lifetime" is 8 years or 100k miles, per the goddamn transmission datasheet

2) Failing ATF looks EXACTLY like this. Works great cold, starts to lose viscosity once warm and fucks up shift timing and power transfer. Mostly a problem at high differential input/output speeds, so you don't really have an issue once the car is /moving/ - just around takeoff.

I changed my (yes manual) tranny fluid around 3 times now, both because I don't believe this lifetime thing and because I have a SMFW which is known to cause noises esp. when it's hot (have no issues like that due to oil combo used).

But regardless, the oil would not make the car rpms drop like a rock. Something in the engine control sometimes picks up late that - *hey - the car is not coasting anymore - time to re-inject some fuel*, and by the time it does all this process the engine's shut off. As to WHAT can cause this late fuel re-injection it is it seems beyond the knowledge of even this formidable community here on the forums...

[DaanBMW]

Just realized I forgot to add the swap of the fuel pump ECU. Added

[Saico]

Daan, try contacting bimmerprofs for a cause diagnosis. AFAIK they do it online remotely. I have contacted them before and they were very helpful.

[DaanBMW]

Originally Posted by Saico

Daan, try contacting bimmerprofs for a cause diagnosis. AFAIK they do it online remotely. I have contacted them before and they were very helpful.

hmm, I will try... The problem I foresee is that the car doesn't really register anything when rpms drop, and even on severe drop causing an engine shutdown it doesn't record much in terms of error codes. This makes troubleshooting difficult.

[rjahl]

Originally Posted by DaanBMW

hmm, I will try... The problem I foresee is that the car doesn't really register anything when rpms drop, and even on severe drop causing an engine shutdown it doesn't record much in terms of error codes. This makes troubleshooting difficult.

Learn to live monitor with INPA.

Or you can try Test-O or Bimmergeeks App to log the engine functions. Take notes are review your logs.

You can monitor actual fuel mixtures, cam positions, load requests. Target and actual values. Short and long term fuel trims, etc . I think you can do about 30 parameters at one time.

[PhaseP]

Originally Posted by DaanBMW

Just realized I forgot to add the swap of the fuel pump ECU. Added

BMS Powerbox, did you ever uninstall it to try?

[lolskylar]

Originally Posted by DaanBMW

Hi Gavin,

In the meantime I did my last-ditch swap: the fuel pump & filter/regulator (both in tank). So full list is: spark plugs, coils, maf, solenoids, vvt motor, camshaft positioning sensors, vvt check valves, fuel pump ECU, ESS (eccentric shaft sensor), fuel pump & filter/regulator.

Result - nothing ! It's as frustrating as it gets.

I'm currently playing around with VVT angle setting thru INPA. While all the ones I tried so far (45 & 135 degrees) are still doing the rpm drop, I want over time to see if one at least avoids killing the engine.

-Dan

Hey Dan.

I have a similar issue, and have done almost all of what you listed.
It sounds like you should be looking in the direction of non-metered air, or insufficient engine vacuum (due to a failed oil-cap seal).
I suggest pressurizing your intake system with smoke. There are some DIY's on youtube to do that.

If that's not an avenue you want to explore, Maybe check out your CCV Diaphram, Mine was cracked, it didn't 100% solve my problem, but it stopped the bucking under hard acceleration.

[DaanBMW]

Originally Posted by PhaseP

BMS Powerbox, did you ever uninstall it to try?

Nope. Are you really suspecting the BMS? I am driving most of the time with it turned off (via pedal) to make sure there's no influence, and it doesn't seem to make any difference. But in terms of disconnecting it entirely I have not tried that

Originally Posted by lolskylar

Hey Dan.

I have a similar issue, and have done almost all of what you listed.
It sounds like you should be looking in the direction of non-metered air, or insufficient engine vacuum (due to a failed oil-cap seal).
I suggest pressurizing your intake system with smoke. There are some DIY's on youtube to do that.

If that's not an avenue you want to explore, Maybe check out your CCV Diaphram, Mine was cracked, it didn't 100% solve my problem, but it stopped the bucking under hard acceleration.

Well, don't put ur money on the ESS, that did nothing for me.

CCV or oil cap should a AOK since I actually replaced my entire valve cover.

As far as false air goes, that would def influence other rpms ranges, like idle or hard acceleration, and I've got no problems there...

[dsuraci]

Long story short. I have been dealing with this low RPM hesitation/stutter for months now. I ran Techron through the system (twice), cleaned MAF, actually had a bad O2 sensor (bank 2, sensor 2) replaced, but the issue still existed. I really did not get consistent codes, but once I did get a misfire on cylinder 2 (via Carly Adapter/App). I was able clear and it never showed again. I decided to order a new set of plugs and coils from FCPEuro. I replaced them over the weekend and the issue is now fixed! Engine now runs "BMW smooth" and I feel like I have a new car again. Just wanted to add my experience to this thread.

Cheers,
Dean

[tino_tino]

I think I have this problem on my N53 3.0 2008 BMW 325i. 55,000 miles.

I'm very tempted to try the fix which has worked as many times in this thread as it hasn't. About 3 each way. Which is to replace all coils and plugs.

However, there is a second possibility I'm strongly considering. I feel like I'd be happy to change the plugs as part of routine servicing, the coils would not be routine... but considering the alternative I think I'd be prepared to risk wasting money on coils just in case that solves the problem easily.

The second possibility, I used to run a workshop specialising in MINIs. When the R56 MINI came out lots of people started getting juddering, loss of power and in worst case not being able to start the car. It would have to come to the workshop on the back of a truck. This was the N14 engine and shares a lot of similarities with the bigger N53 engine I seem to have in my current BMW.

After reading about DISA I ruled that out by removing the intake manifold to look for DISA units. My car doesn't have those. Only an EGR valve and a throttle body.

When running the workshop we had the ability to talk to BMW technicians at the factory and they would recommend testing procedures and fixes.

On their advice for various different cars we developed a smoke testing kit (a smoke pellet inside an oil can with compressed air trickled though) which could theoretically pinpoint holes in the intake system but never proves anything as all the cars we worked on had good intake systems without holes. Perhaps a more common issue on older designs with perishable rubbers?

Another test we were required to do was a leak-down test. That also runs off a workshop air compressor so not the sort of thing you'd really do at home, also, the kit is expensive. A leak-down test is designed to pressurise parts of the engine, if you see air leaking from anywhere you can pinpoint failed components such as cylinder head valves, piston rings... anything which should be airtight to create the compression in the engine so it can run. A percentage of leakage is tolerable.

As mentioned earlier by 'major' (I read the whole thread looking for clues to the issue on my current car) the cars with direct injection do get a lot of carbon build-up on the back of the valves. Some of the 'on-internet' advice even says in extreme cases the valves can get so clogged they bend or snap. We never saw this in any engines but there were pictures of it on the net so maybe it does happen? We also offered walnut blasting to customers who had read about it on the internet and wanted it done. It does clean off a lot of crap from the back of the valves. We never saw much difference in back-2-back tests before and after the work. Engines 'seemed' better but not really night-and-day improvement.

Different customers would sanction different levels of repair on cars depending how many other garages they had tried and whether or not they could afford to experiment. Because remember, new problems aren't known even at the factory where the cars are designed, or else they'd design them differently. So guesswork, diagnostics and experience all play a part in getting to the solution.

We also replaced VANOS solenoids and high pressure fuel pumps for people when they asked. Again, didn't often make a difference.

So above you have most of the things people usually try and all the advice on the internet often points to many of the above listed causes.

Now, what we had more success with than anything else was replacing the valve timing gear on the engine. The aftermarket parts suppliers were offering a kit for about £140.00 which included guides, chain, sprockets.

Not included in the kit was the 'stretch' bolt for holding the cam sprockets onto the camshafts! We had to buy those from BMW for about £10 each.

After a while it dawned on me that maybe the problem was a slipping camshaft sprocket.

I came to this conclusion for several reasons. Firstly, we were getting good results from changing the timing gear. So why was that happening? Secondly, why were some other exterior part replacements sometimes successful, like VANOS solenoids or walnut blasting? Thirdly, why should the bolt which holds the camshaft be of the stretch type (this is when torque stretches the threads and acts as a clamping force for the parts the bolt holds)Â…

My experience on older engines which never had this sort of problem also told me older engines without a VANOS system would have a key on the camshafts and the crankshaft. There would also be TDC and timing marks on the flywheel and camshafts. When rebuilding an engine all you had to do was make sure the timing marks were aligned, the sprockets could only fit on the camshafts in one single position due to the 'key' on the shaft and matching notch in the sprocket.

On the MINI N14 engine (and it seems to be the same on the N53 BMW engine) you have to buy a timing alignment kit to correctly set the position of the camshafts and crankshaft (the valve timing) and it works by holding all the parts in a fixed position. Then you tighten the sprockets onto the ends of the camshafts.

So this is by no means a proven solution as I'm yet to attempt this on my car. I no longer run the workshop so I don't have a garage, diagnostics equipment or any of the usual advantages except for experience.

As I say, I'm very tempted to try the coils and plugs first as it's easier. To try the valve timing issue I'll have to buy a valve timing kit, take off the valve cover, buy some new stretch bolts, line up the crankshaft and fit the valve timing kit before installing the new bolts. It's a lot more work and as mentioned above, half of the quick fix is replacing standard service parts (the plugs) so nothing to be scared of. The other things I've seen people doing on here I'm not willing to try... would rather sell the car!

Sorry for the long post, might help someone.

[tino_tino]

Well I guess I'm just a lucky one....

Not extensively tested yet but over the 5 or 6 miles driven so far I can't make it judder. Tried all the different kinds of conditions which would have usually triggered it. Like accelerating from 1000rpm in 3rd gear, same for 2nd.

I still recommend people think about valve timing if they have a situation where they've tried everything.

My car has been getting worse recently and I had some spare time so went ahead. There have been 2 or 3 occasions recently where I've pressed the start button and it hasn't completed the startup. Most recently it was misfiring when revving from idle like a really old car might of 30 or 40 years ago, had to rev it a couple of times before it smoothed out. The other thing which helped was that Euros had 37% off parts this weekend making it considerably cheaper than it otherwise would be.

A couple of interesting things to note. All the parts taken out were BMW branded so original equipment.

The coils all had what looked like a 2012 date-code on them. That's about 4 years after the car was manufactured so I'm wondering if they had been changed once before? The new coils I put in had a 2019 date-code on them... so I'm assuming the number you can see in the picture is the date?

It wasn't my intention but I managed to buy exactly the same coils and exactly the same spark plugs. They didn't have the BMW logo on but the plugs are NGK and the coils are Bosch. Same as what I took out.

Now, weirdly, the coils which came out all had these black scorch marks on them, if you look to the left on the image close to where the coil meets the plug. Each plug was marked like this, two black marks and two white marks.

To me those scorch marks are a sign of arcing... i.e. the spark prefers to earth to the cylinder head than the plug on some occasions. I disagree with what was said earlier about higher cylinder pressures (at higher rpm) meaning it couldn't be ignition related. I'm not going to guess at all the different conditions you could have inside a cylinder but some food for thought might be that at lower RPM the compressed mixture is in the cylinder for a longer period of time. Also at higher RPMs you may get some assistance from heat and engine speed getting closer to the pre-ignition threshold where the mixture is more volatile so less effort required to ignite it. So I don't think you can point-blank claim ignition issues would manifest throughout the rev range.

If it turns out my luck isn't as good as first thought then I'll come back to update this topic as I found it interesting reading through it. 5 or 6 miles isn't a long test so still plenty of time for it to disappoint me. If you don't hear from me then assume all good.

Here's a picture of the coils, all of them looked like this.

[Phil325i]

There was a recall on coils, which is probably why yours weren't original. Can't understand why you went for the same coil design as you took out. BMW redesigned the coil (by Delphi) to incorporate a heat shield (among other things). These have proved much more reliable.

All explained here:

[tino_tino]

wasn't intentional. The Bosch coils I took out were BMW branded. The replacements had a current date (2019) on them but no BMW branding as they came from Euro Car Parts. I didn't know what was already in there, I bought what was in stock, they just happened to be the same.

[tino_tino]

I suppose if the coil design has been superseded that's good news for people who have old style coils as I had/have in mine. You can be more certain the coils are likely to be the problem. If I have the car long enough for the coils to fail again I'll move to the more modern type.

[juld0zer]

ejenner, I'd say your analysis of the damaged coils is spot on. Ths silicone insulation jacket appears to have leaks. I've not seen an N53 engine in person as they aren't sold in my country but the rocker cover seems similar to the later N52 with the black engine cover, ie. plastic. So the only thing the spark could jump to is the sleeves. I'd expect to see some holes in the sleeves.

On my (early) N52 with the magnesium rocker cover, some bores do have arc damage to them and the corresponding ignition coils also have tears in the silicone jacket.

Is it me or is the silicone swollen in your photo? Or is it just a unique feature of the N53 coils?

[tino_tino]

Not swollen, it's just the colouring around the scorch mark which makes it look a bit bubbly... they aren't deformed, I would've noticed that.

Will be going for a longer drive on Friday, so we'll see how things are after that.

[steifan]

Originally Posted by steifan

Similar issues here with my euro 325i N52B25.

Wall of text:

Noticed when I bought the car in 2014 that the car would often behave strangely when the engine was hot and after driving "normal" with the cruise control engaged the car would "jerk" once and then hesitate when disengaging cruise control and then run week in the lower rpm power band but decent in the upper rpm's, then suddenly it would run "good" with decent low down torque. It didn't bother me much and the car didn't throw any codes (checked with generic Torque and INPA) but I thought there was some connection to the spark plug interval coming up so I replaced those with no improvement. Then on a summer 2 years ago I got a code for the MAF sensor reaching upper limit. Tried cleaning the MAF with CRCs MAF sensor clean, still threw the codes. Car ran better with MAF disconnected so I ran like that for a few weeks. Bought a new MAF and replaced it, no codes. The sporadic hesitation was still there so I started looking into forums and found the VANOS solenoid problems, last summer I tried cleaning the solenoids with brake cleaner and compressed air 2-3 times but it didn't really help (even had the solenoids soaked in isopropanol for 6 hours). Bought new solenoids and put them into the car this spring and the car ran better but the problems still came back. Funny thing is that the car sometimes is so powerful in low RPM's you would think that the tires would tear off on freeway ramps, but I'm guessing that's how it is supposed to run. During this summer the car started throwing the codes P00012, P00015 and P00016 when car was at normal operating temperature, haven't had those codes before and I already replaced the solenoids. The thing is that this summer has been hotter than before and temperatures have been above 86°F and I believe that there is a connection to high outside temperature and the engine struggling. I tried cleaning the VANOS solenoids (the new ones), and switched sides but that didn't help so I did an oil change last week specially checking the oil cap center piece which seems to be all-right, been running the old oil for 3000 miles. Cleaned the VANOS solenoids again during the oil change but the car still threw codes directly after. I found that VANOS could be tested in INPA so I tried that a few times and it seems like the VANOS-solenoids is getting signal and actuating (dunno if it's just set values, hopefully feed back values) but the exhaust camshaft doesn't seem to move during the diagnostic test. Codes are thrown for both sides. I will try the diagnostic again today.

The sporadic issues seems like an electrical fault to me as a mechanical problem would be present "all the time", the car runs really well some times and then the engine does one "jerk" and suddenly runs poorly. Thinking about replacing both cam shaft position sensors as they seem to fail on other cars (intake side on my E46 323Ci and crankshaft sensor on my old Volvo).


Summary:

Car: Euro BMW 325i 2006, N52B25 218hp
Owned since: 2014 (used as summer only car, to spare it from harsh Swedish winters)
Mileage: 51000 miles in 2014, now around 70000

Problems:
* Sporadic low rpm hesitation after a "jerk" when coming out of cruise control for a period, 2014-2017
* Often check engine light and poor performance in hotter weather (above 86°F) from 2018, but can run really good sporadically.
* Sporadic uneven idling, car would sometimes increase idle to 1500rpm and than drop down to around 500.

What I've tried:
New MAF-sensor (because of fault code for high limit/similar)
Spark plugs (after interval)
New VANOS solenoids (after 3x cleaning attempts)
Tighter oil service intervals

What I'm willing to try:
Cam shaft position sensors (because the problems are sporadic - electrical issues? cables getting warm?)


Anyone solved any problems with new camshaft position sensors on N52/N53 engines?

Have since (2018-2019) replaced the MAF connector (to the newer one), the entire PCV-system (source of oil consumption) and replaced the VANOS solenoids again now with genuine ones since one of the cheapo ones threw a code. Haven't got a code related to VANOS or other stuff since I replaced the solenoids a second time but the low down torque is sporadic (sometimes it's good sometimes it's weak).

Today (in 2020) I replaced the 2x VANOS filters/non-return valves while replacing motor oil, did a VANOS diagnostic test in INPA and it seemed to work just fine. Engine felt pretty good after the change, we will se if it persists. The old filters/non-return valves looked good but the lower one had some small visible debris (3-4 "dots") but as bad as pictured before in the thread (no soot residue etc).

Will see how it behaves when the ambient temperature starts to rise in May.

[DaanBMW]

ejenner that sprocket thing is pretty much the 1st time I've heard of it as a potential cause. I assume it's valid for N52 as well, which is port-injected not DI?

[juld0zer]

The coils have been superceeded so many times. Current latest and greatest are the Delphis which came standard from the N20/N55 era onwards. There was a TSB for this exact issue - performance problems with no faults logged - and the fix was to replace all Bosch with the Delphi.

For some reason my motor is a lot more perky after any time I reseat my coils. Even if it is just rocking them side to side after they have been fully seated. My coils are the later Bosch ones with the spring contact inside, not the original click-on type. I recently pulled them all out and added a cable tie around the tips to make the silicone insulators more snug around the plug insulator. I will report back after a few tanks.

The Delphi coil's silicone boots are very snug. We often find them 'glued' to the ceramic insulators on some engines.

[steifan]

Originally Posted by steifan

Have since (2018-2019) replaced the MAF connector (to the newer one), the entire PCV-system (source of oil consumption) and replaced the VANOS solenoids again now with genuine ones since one of the cheapo ones threw a code. Haven't got a code related to VANOS or other stuff since I replaced the solenoids a second time but the low down torque is sporadic (sometimes it's good sometimes it's weak).

Today (in 2020) I replaced the 2x VANOS filters/non-return valves while replacing motor oil, did a VANOS diagnostic test in INPA and it seemed to work just fine. Engine felt pretty good after the change, we will se if it persists. The old filters/non-return valves looked good but the lower one had some small visible debris (3-4 "dots") but as bad as pictured before in the thread (no soot residue etc).

Will see how it behaves when the ambient temperature starts to rise in May.

The car threw some codes for the inner DISA which seemed to have stuck in open position which meant poor low down torque. Replaced it yesterday with a new genuine one and the car seemed to rev fine with good amount of torque from down low (in the practical 2000-3000 rev band). Might have been the inner smaller DISA causing problems from the start, although no codes until now. If it fails to open or close occasionally that would explain that the car could run nice some times and some times not. And finally it stopped working entirely and threw a code. I did not test the old DISA valve.

[wayman519]

I ran into similar issues as most of you in this thread.

To fix this you will need to use INPA to diagnose. ISTA D does not have enough live data feedback to diagnose low rpm hesitations. No faults will be triggered in the ECU for you to to work from.

This shows you how to test vanos:

https://bimmerprofs.com/rough-run-vanos/

This refers to lambda probes (exhaust leak):

https://bimmerprofs.com/n52b30-probl...ulating-probe/

This refers to general fueling issues which can help you find air leaks, fuel pump problems etc:

https://bimmerprofs.com/fuel-mixture-rich-lean/

BIMMERPROFS is an amazing website with incredible knowledge already posted all free. Just read through all their blogs - there is more on diagnosing coils, and injectors.

My problem was faulty VANOS solenoids. No error codes but I was able to compare commanded camshaft position to actual. My values were off by 10 degree's. I replaced the solenoids - ran ISTA D to calibrate the VANOS and check back with INPA. All vanos values were withing 0.3 Degree's.

Hope this helps you guys!