Intermittent VANOS Code 72 - Inlet late valve

[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]

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.

[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]

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]

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.

[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.

[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.

[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.

[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]

Oh duh, this says EGAS not EVANOS. This is an ethrottle issue, so completely unrelated to the VANOS issue. I was primed to see a vanos error!

Ok I'll chase this down separately from this thread and keep it on topic here.

[Pklauser]

After several hours of driving, now I have a "230 Inlet target/actual comparison" error. 🙂

Hasn't triggered a light...yet.

Occurrence details translated:

"Zustand EGAS" - Condition EGAS - not 100% sure what this represents, and why there are no units.
"EDK-Steller Istwert" - EDK Actuator Actual Value - EDK is the throttle actuator, so this happened when the throttle was shut.

Bottom text translates to:

"don't close properly Error currently not present sporadic error" - Cool cool cool

This is pointing me to either VANOS internal seals, which were done with Beisan seals ~4 years and 40k ago, so that seems premature. Granted they weren't done by me, so maybe they were done wrong. Solenoid pack flaking out again, or the intake position sensor dying. Feels like Russian Roulette, any bets on where to start?

[sapote]

1. Challenge was that after the revolution it'd be out again, which I recall being a challenge when I did this years ago. After some iterations, I got it.

2. That could be, but I don't have another VANOS gasket on hand, and I need to drive the car this weekend. In my head this was the easier way, but maybe pulling the VANOS would've been.

1. You did it the right way. It will change because there is back lash in the vanos gear train when doing w/o having vanos pushing the gear train to zero the backlash, and how much slack on the chain pull side.

2. I understand about the vanos gasket.

Hopefully the IN cam timing is correct and no more code.

[Pklauser]

1. Rocked cams til pistons were all the way forward, confirmed visually, and you can feel/hear the piston hitting the end cap. Turn crank one rotation, loosen three bolts, turn crank rotation so now crank and cams are at TDC, lock crank with pin, loosen other three VANOS bolts. Gently turn cam, keeping an eye on the piston to make sure it didn't move. Tighten three bolts, spin engine one full revolution and check again. Challenge was that after the revolution it'd be out again, which I recall being a challenge when I did this years ago. After some iterations, I got it.

2. That could be, but I don't have another VANOS gasket on hand, and I need to drive the car this weekend. In my head this was the easier way, but maybe pulling the VANOS would've been.

[sapote]

1.Got the valve cover torn apart. Using the cam bridge, the exhaust cam is dead-on, and the intake cam is a hair towards the exhaust side.
2. Re-timed the hell out of it until the pin went in like butter. What a pain.

1. How did you get the cams to this point? Did you turn the cams to TDC using the 24mm wrench, or they already settled at the position? How did you know that the cams pushed the vanos pistons to their max forward position?
2. did you remove the vanos, or just loosen the IN hub bolts and finess the hub position relative to the sprocket? I would say this method takes more time to get it right than removing the vanos and bolt it back on the head to set the IN hub to time.

[Pklauser]

Re-timed the hell out of it until the pin went in like butter. What a pain.

No code so far, but that's the neat thing about intermittent problems. At least now I know if it comes back it's not because of the physical timing.