N52 hesitation, stuttering, jerking, surging etc

propaintballa · Post by **propaintballa** » Sat Sep 28, 2019 4:23 pm

enzed4 wrote: ↑Sat Sep 28, 2019 10:31 am I see there are 10 pages of this thread, so apologies if this has been raised. With the N52 engine, have you checked what spark plugs you have? IE, do you have the 4-pole plugs, and not the older single pole plugs? I've just watched a vid where the person was adamant this is the cause of a lot of rough idle problems. (ex-BMW dealer mechanic, seemed to know about the usual N52 problems - DISA valves, solenoids, rough idle, and many of the issues that get raised on this forum).
He pointed out that BMW changed to the 4 pole plugs (I think around 2008?) due to an 'update' - I got a bit confused around here so not sure what was updated (ECU?). Happy to link to the YT vid if you want.

I assume you are talking about "BMW Doctor". The guy is full of sht. I've watched a number of his videos, including that one, and I could see no mention of the 4 pole spark plugs he went on about in his video, on any of the BMW parts sites. As for updated parts, it's pretty common to see older parts superseded as they age, the coils were replaced with Delphi ones as opposed to the original Bosch ones, for example, but from my research, the plugs sadly are not one of them, but thanks for the response!

enzed4 · Post by **enzed4** » Sun Sep 29, 2019 10:02 am

propaintballa wrote: ↑Sat Sep 28, 2019 4:23 pm
enzed4 wrote: ↑Sat Sep 28, 2019 10:31 am I see there are 10 pages of this thread, so apologies if this has been raised. With the N52 engine, have you checked what spark plugs you have? IE, do you have the 4-pole plugs, and not the older single pole plugs? I've just watched a vid where the person was adamant this is the cause of a lot of rough idle problems. (ex-BMW dealer mechanic, seemed to know about the usual N52 problems - DISA valves, solenoids, rough idle, and many of the issues that get raised on this forum).
He pointed out that BMW changed to the 4 pole plugs (I think around 2008?) due to an 'update' - I got a bit confused around here so not sure what was updated (ECU?). Happy to link to the YT vid if you want.
I assume you are talking about "BMW Doctor". The guy is full of sht. I've watched a number of his videos, including that one, and I could see no mention of the 4 pole spark plugs he went on about in his video, on any of the BMW parts sites. As for updated parts, it's pretty common to see older parts superseded as they age, the coils were replaced with Delphi ones as opposed to the original Bosch ones, for example, but from my research, the plugs sadly are not one of them, but thanks for the response!

Yes, YT seems to be much better at entertainment than education

. No one can find what's wrong with the handling in my Z4; I think the garages think I'm mad, but it's enough to make you look elsewhere if you just can't get it resolved satisfactorily. In the back of your mind is the constant nagging thought that it's something simple that's been overlooked, but as you eliminate one thing after another you eventually start giving up

Our03z4 · Post by **Our03z4** » Sun Sep 29, 2019 5:36 pm

Well I changed out the vanos solenoids, seems to idle better, better power band, but still messed up a little while into the drive. Slight coolant leak is coming from the bottom o ring at the coolant tower, have all new on order. Think I might try the valvetronic motor next, if it doesn't work then I'll call it quits.

Checked all the intake lines and they seem to be in great condition.

Capa · Post by **Capa** » Mon Sep 30, 2019 8:46 am

Sounds like ya man BMW DR DEAN. James loves him

I've tried both types of plugs in mine to no avail. I have sort of accepted that it's just a thing that these cars do at this point.

Naylz · Post by **Naylz** » Thu Oct 03, 2019 3:23 pm

I’m also fed up with my Z, similar issue, jerky acceleration. See my MAF post

Capa · Post by **Capa** » Thu Oct 03, 2019 4:40 pm

Yeah - it's totally wazz and not something there's a simple fix for. It doesn't mean the car's broken, more that it's just not running perfectly which skims your enjoyment off it a bit.

Our03z4 · Post by **Our03z4** » Sat Nov 02, 2019 12:32 am

Well I guess my car had to adapt to the new solenoids because it's running so much better! Still feel the back and forth motion but rarely and when I do it's barely noticeable. Also found that the auto transmission thermostat was broken and stuck in the open position. Didn't even know about the part until replacing the coolant tower, luckily the local dealer had one in stock. Now I just have to tackle the wiper fluid leak for the headlights. Love this car again, thanks guys!

propaintballa · Post by **propaintballa** » Thu Nov 21, 2019 3:54 pm

Haven't updated this for a while because I felt like the problem had been resolved. However, it has become apparent that it in fact still exists. Most prominently the problem is this weird pulsing/hunting idle, but also the old symptoms of hesitation when flooring the throttle and surging around 2k rpm.

I thought my large DISA could have broken by now, like the small one, so I thought I'd whip it off to check. I quickly discovered that the DISA is fine, but I had about the same amount of oil come out of my intake as when I replaced the CCV back in March 19 some time. After I replaced the CCV, I noted that removing the oil cap with the engine running meant the car would eventually stall, which it didn't before and didn't on my old Z4C with the N52B30. It is unclear as to whether it is supposed to continue running normally, or stall, despite people citing this action as a way to test the function of the CCV. I am beginning to doubt the quality of the CCV kit due to these issues and the fact I didn't use genuine replacement parts.

This however doesn't explain why the car ran SO much better when I unplugged the old o2 sensors, which eventually lead me to replace them. This car continues to baffle me!

ph001 · Post by **ph001** » Thu Nov 21, 2019 10:05 pm

I took the liberty of checking what happens when I open the oil cap with the engine at idle on my N52K and posted a Youtube video below. You can see that the idle speed does not change at all and there is light suction that can be heard and felt as the cap is opened and closed. This is the blacktop N52K but assume the silver top N52 will be similar.....

https://youtu.be/VhcqVSkhIeA

Naylz · Post by **Naylz** » Mon Mar 22, 2021 4:55 pm

UPDATE: i suffered with the jerky acceleration issues and recurring knock sensor fault codes ever since I bought my 2008 2.5i, as you will see in the post and some of my own I had tried all sorts but eventually gave up and just got used to clearing my fault codes whenever I didn’t want a lumpy acceleration. Anyway over winter and partly because I hadn’t driven it much because I’m shielding I decided to renew the battery, it turned out I had the original 2008 battery still fitted

Now I have a brand spanking new Battery I have not had any issues with the acceleration or any fault codes at all since

my only explanation was the battery dipped too low on start ups that it affected the knock sensor readings, throwing up a fault which the car then tried to compensate for. Very happy now, over two years of ownership and it drives better that ever now

propaintballa · Post by **propaintballa** » Mon Mar 22, 2021 5:18 pm

Naylz wrote: ↑Mon Mar 22, 2021 4:55 pm UPDATE: i suffered with the jerky acceleration issues and recurring knock sensor fault codes ever since I bought my 2008 2.5i, as you will see in the post and some of my own I had tried all sorts but eventually gave up and just got used to clearing my fault codes whenever I didn’t want a lumpy acceleration. Anyway over winter and partly because I hadn’t driven it much because I’m shielding I decided to renew the battery, it turned out I had the original 2008 battery still fitted Now I have a brand spanking new Battery I have not had any issues with the acceleration or any fault codes at all since my only explanation was the battery dipped too low on start ups that it affected the knock sensor readings, throwing up a fault which the car then tried to compensate for. Very happy now, over two years of ownership and it drives better that ever now

Awesome, glad you managed to figure out your fault! Mine still persists. A couple of weeks ago was the first time I had thought about it in months. Part of me thinks the non OEM CCV replacement is the culprit due to the hunting I get when I open the oil cap with the engine running. The other part still thinks it could be to do with the MAF. But then that all goes out the window when I remember that things seemed to get better when I unplugged my pre-cat o2 sensors, lol! Still no codes.

I want to replace the car tbh.

Naylz · Post by **Naylz** » Mon Mar 22, 2021 8:23 pm

How old is your battery? The mad thing is I do remember reading some one actually saying a poor battery does weird things to a z4. I too had given up and had just accepted the issue. If it’s any consolation I smashed a control arm bush the other day on a pothole

propaintballa · Post by **propaintballa** » Mon Mar 22, 2021 8:55 pm

Naylz wrote: ↑Mon Mar 22, 2021 8:23 pm How old is your battery? The mad thing is I do remember reading some one actually saying a poor battery does weird things to a z4. I too had given up and had just accepted the issue. If it’s any consolation I smashed a control arm bush the other day on a pothole

Yeah you're right. I remember checking the voltages though after it had sat and seemed fine. I'm not sure how old it is, but it is at least 3 years old, which is how long I have had the car. Guess I could change the battery then return it if it turns out not to be the issue

I can't believe yours was the original battery! That is pretty good going, if you exclude the issues it caused I suppose haha. Did you have any other issues related to the battery? Trouble starting or anything?

rdm05z4 · Post by **rdm05z4** » Mon Mar 22, 2021 10:46 pm

Propaintballa- might try reaching out to new forum member BLP2 he mentions he is a BMW tech for xx years so he maybe able to give you some guidance.

propaintballa · Post by **propaintballa** » Tue Mar 30, 2021 3:42 pm

rdm05z4 wrote: ↑Mon Mar 22, 2021 10:46 pm Propaintballa- might try reaching out to new forum member BLP2 he mentions he is a BMW tech for xx years so he maybe able to give you some guidance.

I wouldn't dare to burden him with this! Haha. Seriously though, I am considering re-doing the CCV with OE parts, as I have always questioned it since replacing it with cheap parts. Either that, or just sell the car.

Z4-forum.com

Z4-forum.com