Z4 n46... Need a tiny bit of light at the end of the tunnel

[Primitivesmith]

Hi all! A quick update after a few hours today on it!

So there's some warning codes for eps and sim module. But the car seems to start, and idle, rather nicely IF......
The vanos cables (X2 solenoids and the eccentric shaft sensor) are unplugged

If plugged in however, would not start
I've done all the resets through ista etc but it just wouldn't go, instead what I've done is started the car with them off, and then plugged them in while running.

After plugging them in, the car now sits at idle, but has a constant rhythmic surging from about 800 to 900

It seems to restart now its warm with the plugs for vanos in, and revs freely, but is struggling with the idle. I've tried unplugging maf during but no change, inspected all airlines, checked ccv as this was replaced, and like I say coils, Injectors and plugs are all new.

Now I know this is a very common issue, I'm wondering if anyone has any thoughts that spring to mind on it? The only thing I haven't changed was the exhaust side vanos unit, but that seems a bit extreme considering it's fine to start up and run, but then strange again that it would only start to play up idle with vanos plugged in.

I'm going to keep on checking, bu being its about 5 degrees outside I think I'm n nearing my limit :rofl:

Any thoughts are much appreciated

 

[Primitivesmith]

Just a side note, I've also plugged in inpa and ran through some values while it was doing this ugly idle with all things plugged in, and found some unusual results. Especially for adaptation. I'll pin these up now, and if anybody who's had some experience (and it'snt just mostly looking at the pretty lights, like myself :rofl could shed some light on what seems like a very unhappy adaption value, I'd owe you a beer and then some

 

[tug]

A lot of your symptoms are pointing to a bad valvetronic. You can clear the adaptations in Ista or Inpa and start again with the valvetronic having a fresh perspective. If the symptoms persist i would try another valvetronic.

Having said that though, i would have thought a scan would have pointed this out but, the symptoms in my experience are all pointing to the valvetronic. My N46 went through similar troubles a few years back as in, limp mode, very rough idle, xmas tree on the dash, especially EML
which would only go out with a new valvetronic. Once fitted it was like a new car.

Hope this helps,

Cheers, tug

 

[True-Blue]

I feel your pain here O.P. but, please don’t give up on Z4’s…

Just don’t buy any BMW with an N46 in it. The M54 and N52 are two of the most reliable engines you’ll ever encounter, the N46 one of the worst.

For any happy N46 owning owners, no disrespect intended, however, my own experience with this engine in a 3 series was the stuff of nightmares :headbang:

 

[Primitivesmith]

A lot of your symptoms are pointing to a bad valvetronic. You can clear the adaptations in Ista or Inpa and start again with the valvetronic having a fresh perspective. If the symptoms persist i would try another valvetronic.

Having said that though, i would have thought a scan would have pointed this out but, the symptoms in my experience are all pointing to the valvetronic. My N46 went through similar troubles a few years back as in, limp mode, very rough idle, xmas tree on the dash, especially EML
which would only go out with a new valvetronic. Once fitted it was like a new car.

Hope this helps,

Cheers, tug

Hi tug! I must admit the valvetronic was replaced quite near the start with the other vanos bits, due to it being quite obviously faulty, it had no 'graduations' when turning so assumed it to be worn, and now sounds lovely when you put it through the adaptation delete and the learning limit positions thing on ista

It is a curious case though in that every time I've changed a sensor, which is now near as dammit every one related to vanos, it has stopped the codes re emerging. Now, the only faults are sim and eps, and like I say it'll run almost just fine without the vanos plugged in now.

One thought I had but I might be grasping at straws, was that when I retimed the engine when I changed the inlet vanos unit, was that the exhaust unit may have been half full of oil, as in half activated. And then I've retimed the engine, thinking both units in standard position, when actuslly the exhaust was already on half a turn...

I'm not sure but I think I'll investigate this one more time, and then try and think of a plan... H I think I'm up to now :rofl:

 

[Primitivesmith]

I feel your pain here O.P. but, please don’t give up on Z4’s…

Just don’t buy any BMW with an N46 in it. The M54 and N52 are two of the most reliable engines you’ll ever encounter, the N46 one of the worst.

For any happy N46 owning owners, no disrespect intended, however, my own experience with this engine in a 3 series was the stuff of nightmares :headbang:

Hi true, yeah to be honest id have rather gone for a 6 cylinder, in my naivety I didn't even check having had some bmws in the past, I didn't even know they made 4cyl until now! While I was surprised I thought, "maybe that's 2 less things to go wrong" and how silly I feel now :headbang:

But I must admit I've always been partial to that small ' pocket rocket ' style of the z4, I genuinely think its one of the prettiest cars on the road today in that generation of them, and surprisingly OK on fuel from what I've seen

At this point, if I had to sadly get shot of it, would be the biggest waste of money, however if I can get it past this last hurdle and mot'd, I'd like to think she'd have nothing to complain about for a few years being almost entirely new across fuel/air etc

 

[Primitivesmith]

I thought I'd add some additional screen grabs of values at the time, there's things there that bring suspicions to my mind especially where Camshafts are concerned. If anybody could kindly point me in a direction if they've had similar things before they managed to fix, I'd be eternally grateful but for now I'm pretty sure somethings not reading right on the vanos, and I think I'll have to have the rocker cover off again through the week and see what I see

 

[Primitivesmith]

By the way, the camshaft adaption picture where in the car, is when idled
The adaptation value when on the dining table In the kitchen, is the value when put through some revs

 

[tug]

Just don’t buy any BMW with an N46 in it.

HEY YOU! take no notice OP, he's just jealous cos he aint got no work to do on his inferior variant. :lol: