N52 hesitation, stuttering, jerking, surging etc

Thought our quote chain was getting a bit long so I'll just make this a new post haha

I managed to check the DISA valves this weekend just gone. The Foxwell NT530 has an Active Test procedure for the DISA valves. Tested the first one and didn't hear much, but thought this might be normal. Tested the second (the smaller one) and it was clicky and loud. Held my fingers against it and triggered it again, and you can definitely feel the motor actuate and the valve rotate. Went back to the first (big DISA) to test it again and I could feel nothing.

Nice easy job, two bolts for the air filter housing, pull up on some grommets after loosening the hosing, remove all intake boots until you have direct access to the throttle body. There's a cable mount that gets in the way of removing the DISA, you can just remove one bolt and loosen the other and rotate it out the way. 4 bolts on the DISA unit itself, then pry it out with a screwdriver because it's a bit tight.

My valve was knackered. From what I've heard online, it's the common failure point where the little plastic pin on the opposite side of the valve snaps off so it isn't held in place properly. I'm guessing this happened and the strain of holding the whole weight of the valve cooked the motor too. Actuated it with the Foxwell while it was out, it made some strained noises and barely moved, then stopped moving at all haha. Funnily enough, I was super relieved to find a part so badly broken, would have been far worse if there were no broken parts and the mystery continued. Of course, I won't know this was the problem till it's fixed.

Anyway, I ordered a replacement valve from the local dealership recently. Absolute thievery at £270 but I don't want to risk another one breaking, especially if there's the risk of plastic shards being sucked into the intake and damaging the engine. It should be delivered today so I'll pick it up tonight and fit it.

Think I'd be best putting an endoscope down the manifold first just to make sure the plastic pin isn't sitting at the bottom of the manifold waiting to be sucked up. Gonna be a massive pain if it is inside, but better safe than sorry.

Will let you know how it goes! Hope there is no relearn procedure cos I can't recall seeing a DISA relearn on the Foxwell. We'll see. I'm hopeful!
 
Wow, awesome findings. I know what you mean when you say you were happy to find such a serious problem. What I would give for that! The price of those valves is ludicrous for what they are, but good shout on the genuine part, I figured the same thing. I can't remember which one I replaced, but mine were in pretty good shape. I think it was the seal around the flap that had deteriorated on mine, which warranted replacement, but did nothing.

So did you manage to get the small DISA out without removing the manifold?

In other news, I have bought another replacement MAF as the Hella one has always bugged me. I bought from ECP because of good returns policy, but it's not clear what I will be getting. It is listed as Hella but pictured as Continental (which is VDO), so we will see.

toobroke4mods said:
Thought our quote chain was getting a bit long so I'll just make this a new post haha

I managed to check the DISA valves this weekend just gone. The Foxwell NT530 has an Active Test procedure for the DISA valves. Tested the first one and didn't hear much, but thought this might be normal. Tested the second (the smaller one) and it was clicky and loud. Held my fingers against it and triggered it again, and you can definitely feel the motor actuate and the valve rotate. Went back to the first (big DISA) to test it again and I could feel nothing.

Nice easy job, two bolts for the air filter housing, pull up on some grommets after loosening the hosing, remove all intake boots until you have direct access to the throttle body. There's a cable mount that gets in the way of removing the DISA, you can just remove one bolt and loosen the other and rotate it out the way. 4 bolts on the DISA unit itself, then pry it out with a screwdriver because it's a bit tight.

My valve was knackered. From what I've heard online, it's the common failure point where the little plastic pin on the opposite side of the valve snaps off so it isn't held in place properly. I'm guessing this happened and the strain of holding the whole weight of the valve cooked the motor too. Actuated it with the Foxwell while it was out, it made some strained noises and barely moved, then stopped moving at all haha. Funnily enough, I was super relieved to find a part so badly broken, would have been far worse if there were no broken parts and the mystery continued. Of course, I won't know this was the problem till it's fixed.

Anyway, I ordered a replacement valve from the local dealership recently. Absolute thievery at £270 but I don't want to risk another one breaking, especially if there's the risk of plastic shards being sucked into the intake and damaging the engine. It should be delivered today so I'll pick it up tonight and fit it.

Think I'd be best putting an endoscope down the manifold first just to make sure the plastic pin isn't sitting at the bottom of the manifold waiting to be sucked up. Gonna be a massive pain if it is inside, but better safe than sorry.

Will let you know how it goes! Hope there is no relearn procedure cos I can't recall seeing a DISA relearn on the Foxwell. We'll see. I'm hopeful!
Click to expand...
 
propaintballa said:
Wow, awesome findings. I know what you mean when you say you were happy to find such a serious problem. What I would give for that! The price of those valves is ludicrous for what they are, but good shout on the genuine part, I figured the same thing. I can't remember which one I replaced, but mine were in pretty good shape. I think it was the seal around the flap that had deteriorated on mine, which warranted replacement, but did nothing.

So did you manage to get the small DISA out without removing the manifold?

In other news, I have bought another replacement MAF as the Hella one has always bugged me. I bought from ECP because of good returns policy, but it's not clear what I will be getting. It is listed as Hella but pictured as Continental (which is VDO), so we will see.
Click to expand...

Unfortunately, I'm back here with you. A serious problem, but apparently not the cause of my woes because even with the new valve fitted, the engine runs no better. Maybe I'll notice a difference when the rest of the engine is sorted, but right now, it's hard to feel like this was money well spent. I'm quite frustrated, to say the least.

I never checked the small DISA. It seemed perfectly responsive when testing with the Foxwell, so I didn't bother pulling it out. No codes from it either, so it should be good for now.

The problems continue. I could keep throwing money at it trying to guess which part is broken, but I think I'm gonna get it to a local independent BMW shop. I'll keep looking in the mean time of course, but I'll probably spend just as much money in the garage as I would trying to fix it myself, but with less crushing disappointment.

Hope your new MAF improves things for you a bit. I'm going to move my issue into a new thread to look for any other suggestions there and to avoid hijacking yours. Cheers for your help with my issue, I'll update you here if/when I get the problem sorted in case it's relevant to you too.
 
Thorttle01 said:
Thank you for your reply and ideas!

My car have now 150k miles on the clock. I tested my CCV according this: https://bimmerprofs.com/crankcase-ventilation/ and my STFT does not change dramaticaly if I open oil cap, it takes a while to STFT starts to grow.

I have little oil around eccentric shaft sensor seal. Cleaning connector did not helped for me. New seal ordered and is on the way to me.
Did you think, that oil in connector or bad sensor can make these problems even if no MIL is triggered, errors not saved in ECU camshaft angle is like expected in INPA?

My short term fuel trims are little negative (rich) on both banks , so no expectation for vacuum leak or lean mixture.
STFT_B1=-0,5mg/stk
STFT_B2=-0,4mg/stk
LTFT_B1=+2,5%
LTFT_B2=+1,8%

My MAF was cleaned, but no change in behaviour were observed. Live data from MAF are looking good, but I think that the value is little bit low at idle. I have only 11kg/h at idle. Can someone share his airflow value at idle with same engine??

* My car behaves not constant in time... One day more surging and huge lack of torque / other day much better. But I can confirm
, that my car is down on power. In first situation, definitely not by 25bhp.... it feels like aroud 100bhp drop! My previous car was E36 with M52B28 engine (192bhp) and I had same or better acceleration and but mooooore torque!

I ordered exhaust back pressure gauge for cats testing. It should arrive soon, then lets see...
Click to expand...

Did you ever get this issue sorted? When I first checked this thread, I didn't think your post was relevant to my issue, but now that I've tried replacing more parts, you and I sound like we have pretty much the exact same problem, also with no codes to give me hints. Like you, I would also like to check out the cats for clogging when I can, but not sure the best way to go about getting in the exhaust manifold (maybe through O2 sensor holes?). Cheers.
 
toobroke4mods said:
Unfortunately, I'm back here with you. A serious problem, but apparently not the cause of my woes because even with the new valve fitted, the engine runs no better. Maybe I'll notice a difference when the rest of the engine is sorted, but right now, it's hard to feel like this was money well spent. I'm quite frustrated, to say the least.

I never checked the small DISA. It seemed perfectly responsive when testing with the Foxwell, so I didn't bother pulling it out. No codes from it either, so it should be good for now.

The problems continue. I could keep throwing money at it trying to guess which part is broken, but I think I'm gonna get it to a local independent BMW shop. I'll keep looking in the mean time of course, but I'll probably spend just as much money in the garage as I would trying to fix it myself, but with less crushing disappointment.

Hope your new MAF improves things for you a bit. I'm going to move my issue into a new thread to look for any other suggestions there and to avoid hijacking yours. Cheers for your help with my issue, I'll update you here if/when I get the problem sorted in case it's relevant to you too.
Click to expand...

Dammit, that is incredibly frustrating. Sad to think I was in that exact position a couple of years ago after dropping £250+ on that DISA valve. I think a good BMW specialist is a good shout, sadly I never found a decent one near me. I did take mine to one near my Mum's a while back to get them to update the DME, which cost less than 50 quid, which might be worth a shot, but maybe they have seen the problem before and can offer more insight.

In my news, I just received the new MAF and it is sadly actually a Hella unit, not the continental/VDO unit that was pictured. I will give that a shot but it will likely be returned :/
 
propaintballa said:
Dammit, that is incredibly frustrating. Sad to think I was in that exact position a couple of years ago after dropping £250+ on that DISA valve. I think a good BMW specialist is a good shout, sadly I never found a decent one near me. I did take mine to one near my Mum's a while back to get them to update the DME, which cost less than 50 quid, which might be worth a shot, but maybe they have seen the problem before and can offer more insight.

In my news, I just received the new MAF and it is sadly actually a Hella unit, not the continental/VDO unit that was pictured. I will give that a shot but it will likely be returned :/
Click to expand...

I actually first tried my usual garage that I get my car's MOT'd at and after describing the problem and what I've tried, the bloke on the shop told me it would be a waste of everyone's time and money if I took it to them because they don't have the kit to test it properly. Apparently they broke their fuel pressure gauge recently and haven't replaced it, and don't have BMW scanning tech. They referred me to a garage down the road, who THEN referred me to a local BMW indy shop that I haven't heard of before, but has a good reputation. A better reputation than the other shop I know about, at least. At this point, I'm kinda willing to just throw a few hundred quid at it if they can be confident it will sort the issue, I miss my car! And I'm convinced that not having the freedom to scare myself occasionally is even affecting my mood in general, sometimes losing traction on a dodgy corner is all you need to appreciate the little things in life! I've heard a lot of people mention this software update, but there is very little info about what the bad update causes and how the new one is any different. I'll inquire in any case.

Shame about the MAF. Am I right in thinking that Siemans is the OEM brand? Mine is a Siemans, at least. I think in general, if the car runs the same or worse with the MAF unplugged, then the MAF is not the problem. Unplugging a dodgy MAF should make the car run better, but if there is no improvement, perhaps it's not that?
 
toobroke4mods said:
I actually first tried my usual garage that I get my car's MOT'd at and after describing the problem and what I've tried, the bloke on the shop told me it would be a waste of everyone's time and money if I took it to them because they don't have the kit to test it properly. Apparently they broke their fuel pressure gauge recently and haven't replaced it, and don't have BMW scanning tech. They referred me to a garage down the road, who THEN referred me to a local BMW indy shop that I haven't heard of before, but has a good reputation. A better reputation than the other shop I know about, at least. At this point, I'm kinda willing to just throw a few hundred quid at it if they can be confident it will sort the issue, I miss my car! And I'm convinced that not having the freedom to scare myself occasionally is even affecting my mood in general, sometimes losing traction on a dodgy corner is all you need to appreciate the little things in life! I've heard a lot of people mention this software update, but there is very little info about what the bad update causes and how the new one is any different. I'll inquire in any case.

Shame about the MAF. Am I right in thinking that Siemans is the OEM brand? Mine is a Siemans, at least. I think in general, if the car runs the same or worse with the MAF unplugged, then the MAF is not the problem. Unplugging a dodgy MAF should make the car run better, but if there is no improvement, perhaps it's not that?
Click to expand...

Yeah it's a bloody nightmare! I know what you mean, nothing like a bit of a near death experience to remind you you're alive! :D I actually have a fuel pressure gauge which I got about a year ago and still haven't tested haha. Or was it a compression tester... I can't even remember at this stage haha. According to things I read, the update just improved driveability based on aging of various components. As for the MAF, yeah you're right, that's how it SHOULD work, but based on my experience with the o2 sensors being that when I unplugged them the car ran much better, but when I replaced them there was no change, I am inclined to disregard that train of thought. I have learnt these cars do really weird things for really weird reasons :P

Where are you based out of interest? If local we could always look at each other's problems haha
 
propaintballa said:
Yeah it's a bloody nightmare! I know what you mean, nothing like a bit of a near death experience to remind you you're alive! :D I actually have a fuel pressure gauge which I got about a year ago and still haven't tested haha. Or was it a compression tester... I can't even remember at this stage haha. According to things I read, the update just improved driveability based on aging of various components. As for the MAF, yeah you're right, that's how it SHOULD work, but based on my experience with the o2 sensors being that when I unplugged them the car ran much better, but when I replaced them there was no change, I am inclined to disregard that train of thought. I have learnt these cars do really weird things for really weird reasons :P

Where are you based out of interest? If local we could always look at each other's problems haha
Click to expand...

OK, the update sounds interesting then. I had kinda heard it was supposed to stop VANOS solenoids clogging with crud, but not really sure how that's supposed to work.

My car doesn't run any better but now I'm wondering about the O2 sensors too. Does it have the same effect if either the O2 sensors or the MAF are unplugged? I couldn't even find where the O2 sensors connect, the cable into the sensor seems to actually be part of it, so I wasn't able to disconnect them to try it. I've heard folks talk about dying batteries causing weird issues with these cars, but my battery was last replaced at the end of 2019 with a £160 Bosch one, 5 year warranty (although not sure if the previous owner actually registered for the warranty). I doubt it would be battery in my case, seems to hold a voltage.

I'm based in Herefordshire. I don't remember seeing a location on your profile or previous posts, so not sure how far that is from you... not that I can travel far at the moment haha. Here's hoping the mechanics perform a miracle on Monday!
 
toobroke4mods said:
OK, the update sounds interesting then. I had kinda heard it was supposed to stop VANOS solenoids clogging with crud, but not really sure how that's supposed to work.

My car doesn't run any better but now I'm wondering about the O2 sensors too. Does it have the same effect if either the O2 sensors or the MAF are unplugged? I couldn't even find where the O2 sensors connect, the cable into the sensor seems to actually be part of it, so I wasn't able to disconnect them to try it. I've heard folks talk about dying batteries causing weird issues with these cars, but my battery was last replaced at the end of 2019 with a £160 Bosch one, 5 year warranty (although not sure if the previous owner actually registered for the warranty). I doubt it would be battery in my case, seems to hold a voltage.

I'm based in Herefordshire. I don't remember seeing a location on your profile or previous posts, so not sure how far that is from you... not that I can travel far at the moment haha. Here's hoping the mechanics perform a miracle on Monday!
Click to expand...

That sounds like bs to me! The software update couldn't possibly achieve that! You have a 3 series, right? The pre-cat o2 sensors connect to the rear left of where they are located. I think they are clipped to the side of the strut mount area. Batteries are another thing, battery coding when it is replaced is relatively important too. Tbh though, if your battery is that new I doubt that would be causing issues.

Interestingly, I installed the new MAF earlier and initial results are promising. I haven't reset adaptions and it feels quite a bit better. Going to give that a few days and see what happens!

Ahhh, I am in Nottingham, so not particularly close!
 
propaintballa said:
That sounds like bs to me! The software update couldn't possibly achieve that! You have a 3 series, right? The pre-cat o2 sensors connect to the rear left of where they are located. I think they are clipped to the side of the strut mount area. Batteries are another thing, battery coding when it is replaced is relatively important too. Tbh though, if your battery is that new I doubt that would be causing issues.

Interestingly, I installed the new MAF earlier and initial results are promising. I haven't reset adaptions and it feels quite a bit better. Going to give that a few days and see what happens!

Ahhh, I am in Nottingham, so not particularly close!
Click to expand...

Exactly! And yeah, I have an E92 3 series. I will have a look at where those sensors connect tomorrow. I found some connectors of the same colour near the fuel rail on the intake side, but I saw the BMW Doctor mention that these were the post-cat O2 sensors when talking about removing the intake manifold, so I wasn't sure. I'm still very envious of you Z4 owners (especially the gorgeous E86 coupe) and your massive engine bays with easy access! I can only just see 4 of the 6 cylinders under the cabin filter housing haha.

Let's hope your new MAF has helped. How bad is the problem in general now, compared to a 100% correct motor? I have heard another N52 owner mention that while troubleshooting another issue, their car performed well during the relearn procedure, but once it had learnt, things were just as bad as before.

My car's due in the indy specialist on Monday. Feels like forever away, another weekend without the car. Hoping they are able to resolve it, fingers crossed it won't be too pricey! Unlike the Z4s which seem to have held their value a bit better (especially the E86 again), my E92 is only worth a couple grand so anything too expensive doesn't make a lot of sense. I'm really hoping they are able to fix it and even better if it doesn't bankrupt me! I'll update you when I know more.
 
toobroke4mods said:
Exactly! And yeah, I have an E92 3 series. I will have a look at where those sensors connect tomorrow. I found some connectors of the same colour near the fuel rail on the intake side, but I saw the BMW Doctor mention that these were the post-cat O2 sensors when talking about removing the intake manifold, so I wasn't sure. I'm still very envious of you Z4 owners (especially the gorgeous E86 coupe) and your massive engine bays with easy access! I can only just see 4 of the 6 cylinders under the cabin filter housing haha.

Let's hope your new MAF has helped. How bad is the problem in general now, compared to a 100% correct motor? I have heard another N52 owner mention that while troubleshooting another issue, their car performed well during the relearn procedure, but once it had learnt, things were just as bad as before.

My car's due in the indy specialist on Monday. Feels like forever away, another weekend without the car. Hoping they are able to resolve it, fingers crossed it won't be too pricey! Unlike the Z4s which seem to have held their value a bit better (especially the E86 again), my E92 is only worth a couple grand so anything too expensive doesn't make a lot of sense. I'm really hoping they are able to fix it and even better if it doesn't bankrupt me! I'll update you when I know more.
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Oh god, not the 'BMW Doctor', we have talked about that guy on this thread before! I'm in an E91, so same boat as you regarding the scuttle panel. I'll try get a picture of the o2 sensor connectors for you tomorrow if I remember! Yeah that's definitely a thing, I experienced that myself, I reset adaptions today and it ran pretty poorly, particularly on first start, which kind of reassures me an amount that they are reset and indeed relearning. In general, the problem seems 90% fixed, but then I haven't driven much. Sometimes the issue is REALLY obvious and other times it's more subtle. It seems to depend on the weather and road surface as well.

Got all my fingers crossed for you on Monday! Haha. I too will keep you and the thread updated as the adaptions are relearnt and I drive some more. I'll be driving for around an hour tomorrow so that should be a good opportunity to test!
 
Okay so quick update, drove for over an hour today and the problem still exists for the most part. It's still learning adaptions though, but it doesn't look promising, though it does seem better. I wouldn't be surprised if I could get a VDO MAF that it would solve the issue, but maybe I am just being optimistic.

On another note, I managed to get a couple of pictures of my pre-cat o2 sensor connectors. The pics aren't great because it was raining and I had to rush. The rear sensor connector is also quite hard to see without the scuttle panel removed too. As I was writing this I suddenly remembered that there was a little metal bracket which was a pain to get out, so I didn't bother putting it back, which may be why you're struggling to find it. This video illustrates that pretty well... https://www.youtube.com/watch?v=FToeaTyhy24&ab_channel=WorldMechanics
 
Strap in, this is a long one.

I've just checked my previous posts and I'm kicking myself for not having mentioned this sooner because it could have saved me some money: my car currently has the ABS trifecta. Red brake light, ABS and DSC. In addition, SRS and airbag light, and no speedo or odo. I guess I never mentioned this because I thought it couldn't be related, and I feel quite the fool for it.

Anyway, dropped my car off Sunday night to be picked up Monday morning by the garage. They took ages to get back to me, didn't hear back until about 2:30pm. When I did, they told me that both rear wheel speed sensors were gone... I already knew this thanks to the Foxwell, and I even told them this before it went in. Anyway, they quoted between £400 and £500 to order and replace both wheel speed sensors. I declined and said I'd pick the car up later. Charged me £115 (incl. VAT) for the pleasure of telling me I had a problem I already knew I had. I didn't think it would be related because the DME or dash didn't display any low power messages, so I assumed it must be something mechanically wrong with the engine. Apparently not, just a difficult car.

Anyway, called up the local BMW dealership and placed an order for the sensors. Quoted exactly what the indy garage wanted (£226 incl. VAT before discount). I asked the bloke on the phone (who recognised me this time...) if ABS issues can cause low power, and he said this is something he's seen a couple times before, especially if the sensor shorts on the ring, and warned me it could be the reluctor rings, as the garage did. In the end, he even gave me £10 off because these sensors make it £750 I've spent on parts at the dealership since August.

I feel pretty silly about spending so much for them to run a diagnostic which pulled up the EXACT same stuff I already knew and not actually do any work. They seemed happy with the state and operation of the engine so at least I don't need to worry about damaging it if I need to drive. Still, feel like I've been properly mugged off.

The wheel speed sensors arrived yesterday (Tuesday) and I have fitted them today. Cleared all related codes in all modules, restarted the car and great news, the car is back to full power and running great. The ABS Trifecta did some back up, but this is a different code that says something along the lines of "Increment gear" on the left rear sensor. I'll have to look this up and find out what 's wrong with that, I know the ring is burgling due to rust but I will fix that another time. I did briefly develop a really rough misfire in cylinder 5 on my test drive while pushing it, but I pulled over, restarted the engine and it hasn't come back yet. I will swap the coils with another cylinder and see if the code moves there, if it comes back at all.

This incident with the garage has a silver lining: I am more confident in my ability to diagnose issues. At a certain level of mechanical and technical understanding of a specific engine, garages are next to useless. I felt I had exhausted all options when it came to fixing problems with the engine and I was stumped. Turns out I was right, the engine was fine and my issues were caused by an issue that I dismissed as unrelated. If I had searched a bit harder, I would have found others with low power issues related to ABS faults. Part of me let folks at work get to me, doubting my ability to fix issues with my car because I haven't been trained ("Just take it to a garage!"), but fixing your own stuff is how most mechanics came up in the first place. And as it happens, the garage was bloody useless anyway. Last time I'll be using a garage for anything except MOTs or jobs I CBA to do. I have another story about my last car and knowing better than garages, but this post is already torturously long so I'll leave it for another time.

Anyway, this largely resolves my saga. I'll still hang around because I feel the knowledge of this engine I've picked up from trying to diagnose this issue may be able to help others. Funnily enough, my mum sent me a meme today that said "Life is like a BMW car; you never know what will f*ck up next." Truer words are hard to come by...
 
Well... That's all she wrote. Got rid of the car over the weekend. I never did get it how I wanted it, but still performed really well and was great to drive with a lovely engine note that will be sorely missed in my new diesel wagon.
 
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