Intermittent VANOS Code 72 - Inlet late valve

[Slideways]

If it ends up coming back, the intake piston seal could have been slightly damaged when it was installed. Another forum member pulled the pistons out to find that they had a damaged seal (install error), but I don't know what codes they had.

[Pklauser]

Well boo, code 72 came back, this time joined by its friend 184 - camshaft actuation. Again intermittent though, I've only seen it once in roughly 1k miles.

This is leading me to think it's either the VANOS seals - which are ~4 years old, or this new solenoid pack from a year ago is junk.

[Pklauser]

Replaced the intake cam sensor as it was original, just in the off chance that would change behavior here. 72 came back.

Interestingly enough INPA gives a little more metadata with the error:

Line break or value missing
Error Emission Relevant OBD
Error currently not present sporadic error

"Line break or value missing" is interesting to me. Can't tell if that's just generic text that gets tossed in there with the code, or if this is trying to lead me to a more direct cause, which would make me think solenoid pack over piston seals. I'd also expect bad piston seals to show poor VANOS test results.

I got my solenoid pack from FCP, so I can easily order another and do a replacement, but it feels shitty to do that if the solenoid pack isn't actually the problem.

I think my next step is going to be to pull apart the VANOS unit itself and inspect/replace the seals. This was done by the PO, but not by me, so maybe there is a suspect seal in there somewhere.

[heinzboehmer]

"Line break or value missing" sounds like a SW thing to me, not mechanical. Not entirely sure what INPA is trying to communicate here though, maybe someone else can chime in.

[sapote]

Replaced the intake cam sensor as it was original, just in the off chance that would change behavior here. 72 came back.

Interestingly enough INPA gives a little more metadata with the error:



"Line break or value missing" is interesting to me. Can't tell if that's just generic text that gets tossed in there with the code, or if this is trying to lead me to a more direct cause, which would make me think solenoid pack over piston seals. I'd also expect bad piston seals to show poor VANOS test results.

I got my solenoid pack from FCP, so I can easily order another and do a replacement, but it feels shitty to do that if the solenoid pack isn't actually the problem.

I think my next step is going to be to pull apart the VANOS unit itself and inspect/replace the seals. This was done by the PO, but not by me, so maybe there is a suspect seal in there somewhere.

Man that's a lot of work to replace IN cam sensor for nothing.
Are the text in the same screen with code 72?
Before blaming the vanos solenoid you should try to read the cam angle to see how far off it is; if a little off then the solenoid is working, and if it's off a lot then the vanos piston did not move.

[Pklauser]

Man that's a lot of work to replace IN cam sensor for nothing.
Are the text in the same screen with code 72?
Before blaming the vanos solenoid you should try to read the cam angle to see how far off it is; if a little off then the solenoid is working, and if it's off a lot then the vanos piston did not move.

Yep, text is in the same screen with the 72. Attached the INPA screenshot.

Tough thing with reading the cam angle is that the issue is intermittent. My thought is that since the VANOS test is successful, the solenoid and piston are at least working as expected some of the time. I suppose I could drive around and watch the cam angles, but without knowing what they should be, it will be hard to tell if it's "off". Even then, I'd have to catch it, which seems like a crapshoot.

I have a pressure gauge and banjo I bought years ago to measure VANOS pressure, I'm going to check that out and see what it looks like while running the test, if anything just to have a data point before I pull all of the VANOS off again.

[sapote]

All error occured with hot engine (93C one time which is hotter than normal), and above 2500 rpm so the vanos was activating. No error happened with cold engine, interesting point. Yes, check vanos oil P at hot engine.

[Pklauser]

Alright VANOS oil pressure definitely seems low. By this thread it sounds like I should expect ~115 bar at hot idle. I'm seeing ~40 💀.



Also see this video of the pressure while the VANOS test is running via Tool32. RPM bump brings the pressure up to 60 bar, but it's all still way too low.

https://www.youtube.com/watch?v=xsGHc2ilpt8

Edit - Adding that I have a Beisan re-drilled OE disk that was installed by the PO. Motor is a bit of a frankenstein, but the VANOS unit presumably has 170k on it.

[maupineda]

Alright VANOS oil pressure definitely seems low. By this thread it sounds like I should expect ~115 bar at hot idle. I'm seeing ~40 💀.



Also see this video of the pressure while the VANOS test is running via Tool32. RPM bump brings the pressure up to 60 bar, but it's all still way too low.

https://www.youtube.com/watch?v=xsGHc2ilpt8

Edit - Adding that I have a Beisan re-drilled OE disk that was installed by the PO. Motor is a bit of a frankenstein, but the VANOS unit presumably has 170k on it.

I had hesitation issues when I had low pressure, also it will always pass VANOS tests, but the time to adjust was high (close to 300ms)

you want at least 100bar with oil at operating temp (75 to 90).

If the pressure is low the adjustment will be erratic if the engine needs to adjust cams continuously, as it would be during city driving or roads with varying load conditions.

the issue with redrilled discs is that you are shooting in the dark as those could be worn and drive lower pressure

beisan sells new units for not that much (1500). I actually asked them for a unit which disk was not removed and original to the unit, this meant no redrill.

edit: like you my pressure wan in the 40’s bar too.

[Pklauser]

I had hesitation issues when I had low pressure, also it will always pass VANOS tests, but the time to adjust was high (close to 300ms)

you want at least 100bar with oil at operating temp (75 to 90).

If the pressure is low the adjustment will be erratic if the engine needs to adjust cams continuously, as it would be during city driving or roads with varying load conditions.

the issue with redrilled discs is that you are shooting in the dark as those could be worn and drive lower pressure

beisan sells new units for not that much (1500). I actually asked them for a unit which disk was not removed and original to the unit, this meant no redrill.

edit: like you my pressure wan in the 40’s bar too.

Awesome, I'd seen your posts in the other VANOS threads and it seemed like we had similar diagnoses, really appreciate you chiming in here.

I can ask Beisan as well, but will they not redrill the disk that's original to the unit and keep them as a pair? How did you mitigate the exhaust hub tab shearing issue without a redrilled disc, VAC hub?


Edit - Reading from Beisan here it actually sounds like they might keep the disc and unit as a pair?

"NEW oil pump disk upgraded with precise CNC machined smaller holes to prevent exhaust tab breaking, as Beisan-Systems BS025, but with the brand new disk."

[maupineda]

Awesome, I'd seen your posts in the other VANOS threads and it seemed like we had similar diagnoses, really appreciate you chiming in here.

I can ask Beisan as well, but will they not redrill the disk that's original to the unit and keep them as a pair? How did you mitigate the exhaust hub tab shearing issue without a redrilled disc, VAC hub?

I had spent so much I just wanted zero risk, like what if they disassembled the unit and mixed with another one’s disc, things like that made me ask for an unmolested unit. And yes, I chose the VAC hub route.

[Pklauser]

I had spent so much I just wanted zero risk, like what if they disassembled the unit and mixed with another one’s disc, things like that made me ask for an unmolested unit. And yes, I chose the VAC hub route.

Yea I get that.

It's kind of weird to me that they take VANOS cores back, but they don't sell refurbished VANOS units. Surely they're not paying us $500 just to harvest the pump disc they sell for $150, or the solenoid they sell for $200. The math ain't mathing. Call me superstitious, but it does kind of rub me the wrong way.

They're super responsive, but when I asked about their warranty they said they've never had a customer's product replaced. I think the failures and discontinuation of their own in-house pump disc disproves that statement.

Hate that I have to get into non-OE solutions no matter which way I proceed here. Feels like risk in the pump disc world, feels like risk in the hub world.

[maupineda]

FWIW, the unit I got seemed brand new, and came in what seemed manufacturer’s packaging. The bolts all were torx as BMW had updated all those fasteners towards the end of the life of the S54’s everything in the unit seemed new. I chose not to send the core unit back so my price was close to 2K for the whole unit.

The new units for sure are legit, and 2k ain’t exactly cheap, but surely there is margin in there. It can possibly be they have a line of business with the VANOS supplier and the cores are needed for remanufacture purposes. Who knows. But the new units cure my pressure issue. I measured it at 110 bar.

[sapote]

Edit - Adding that I have a Beisan re-drilled OE disk that was installed by the PO. Motor is a bit of a frankenstein, but the VANOS unit presumably has 170k on it.

Either the pump is inefficient (pistons not matched to disk holes) or vanos has too much internal leak (pistons seals, P regulator, etc)