VANOS Sticking? Can't figure out the problem

[mleveroni]

To start the car is on a Syvecs standalone, so no codes, just looking at data.

I am having an issue with the intake cam sticking intermittently. It will lazily move to its target position, then not return until seconds after. The picture below is 2000rpm-5500rpm log, yellow is the target, purple is the actual position, and blue is the duty. It increases duty to try to get it to move, which it does slowly. Then it increases more towards the end for no apparent reason, then does not return to the target after. The solenoid, vanos seals, and diaphragm springs are all new. The exhaust cam is also working fine.

I am out of ideas on what the issue is, so any suggestions would be greatly appreciated. Thanks in advance.

[maupineda]

Do you have any drivability issue? I am of the thought that the “internet advise” of using S62 diaphragm springs on the S54 VANOS hubs is actually a bad idea as there is more preload and effort for the timing adjustment to occur. Geometric Tolerances in the system may actually cause functional issues if all lines up on the worse side of the things

BMW, and any power train engineer for that matter, are not stupid. They used different diaphragms for a reason, why tooling up a new part that otherwise is almost the same, just thicker?

i have seen my adjustment times are much slower than when using the right parts. I am actually changing them back to S54 items in the next chance (200ms v 400ms)

if you have a worn pump and the S62 items… well, you make a judgment. Have you measure VANOS pressure?

[mleveroni]

Do you have any drivability issue? I am of the thought that the “internet advise” of using S62 diaphragm springs on the S54 VANOS hubs is actually a bad idea as there is more preload and effort for the timing adjustment to occur. Geometric Tolerances in the system may actually cause functional issues if all lines up on the worse side of the things

BMW, and any power train engineer for that matter, are not stupid. They used different diaphragms for a reason, why tooling up a new part that otherwise is almost the same, just thicker?

i have seen my adjustment times are much slower than when using the right parts. I am actually changing them back to S54 items in the next chance (200ms v 400ms)

if you have a worn pump and the S62 items… well, you make a judgment. Have you measure VANOS pressure?

I did just replace them with S62 springs, however I was having the same issue before that on the original S54 springs. I have not pressure tested the vanos yet, I will do that soon.

[Cubieman]

Are you using an OEM pump disc? Are your cam sleeve bolts OEM/Lang Racing?

Beyond the S62 diaphragms, which I opted to remove the only other thing I can think of besides low pressure would be your cam bolts protruding out enough to cause interference.

It's odd your exhaust cam is OK, you would think a pressure issue would affect both cams unless the valve block/solenoid pack have issues.

Another part to look at if all else fails would be the Vanos inlet valve, but again I would think if it was having issues both cams would be as well.

[mleveroni]

Are you using an OEM pump disc? Are your cam sleeve bolts OEM/Lang Racing?

Beyond the S62 diaphragms, which I opted to remove the only other thing I can think of besides low pressure would be your cam bolts protruding out enough to cause interference.

It's odd your exhaust cam is OK, you would think a pressure issue would affect both cams unless the valve block/solenoid pack have issues.

Another part to look at if all else fails would be the Vanos inlet valve, but again I would think if it was having issues both cams would be as well.

Oil pump disk is Beisan and hub is Turbotoy. Bolts are Lang Racing. Inlet valve is also new. I just ordered the equipment to test the pressure and a new pressure accumulator. So I am going to test it as it is now and with a new accumulator. The whole solenoid pack and block are brand new, but is it unheard of to have a brand new unit be bad? Having one cam work fine is confusing but a pressure issue would make sense.

[Cubieman]

Oil pump disk is Beisan and hub is Turbotoy. Bolts are Lang Racing. Inlet valve is also new. I just ordered the equipment to test the pressure and a new pressure accumulator. So I am going to test it as it is now and with a new accumulator. The whole solenoid pack and block are brand new, but is it unheard of to have a brand new unit be bad? Having one cam work fine is confusing but a pressure issue would make sense.

I unfortunately had pressure issues with my Beisan disc, both cams were in the 400ms+ range and pressure itself was less than half of what the OEM disc produced.

[maupineda]

Agree, you may have a pressure issue. I had pressure issues with a Beisan disc and since I had lost my original to my car disk, I had to source a VANOS spare unit.

[mleveroni]

Very interesting I had no idea. If it turns out I do have a pressure issue and a new accumulator doesn't help, I will look into that next. Thank you for the advice.

[maupineda]

Very interesting I had no idea. If it turns out I do have a pressure issue and a new accumulator doesn't help, I will look into that next. Thank you for the advice.

The acc is like an oil capacitor, provides oil at pressure when pressure supplied drops due to VANOS operation. It is there to maintain pressure at all times, but if the pump pressure is low, the acc cannot compensate for it.

[Martyn]

What frequency are you running the vanos solenoids?

What values do you have for the Vanos PIDs?

[mleveroni]

What frequency are you running the vanos solenoids?

What values do you have for the Vanos PIDs?

This I do not know, the info about the vanos is all coming from the tuner reviewing the logs.

[mleveroni]

The acc is like an oil capacitor, provides oil at pressure when pressure supplied drops due to VANOS operation. It is there to maintain pressure at all times, but if the pump pressure is low, the acc cannot compensate for it.

I see, nonetheless I'll have to wait for the pressure testing equipment before I have more useful information. It is also worth noting that this is a fresh motor with around 80 miles on it, first 50 of that having SAE30 break-in oil in it. Is it possible that there is enough of that break-in oil lingering around and causing issues?

[Martyn]

Personally it smells like a tuning issue. Your tuner should have tuned the vanos control PIDs to get the vanos moving quickly to the target without overshooting.

[eacmen]

I’m waiting for the “sweet tooth” fanatics to chime in 😂.

I suspect oil pressure or some issue with the syvecs not properly driving the solenoid.

Curious why is there ringing in the yellow trace? That’s the ECU target cam position? Would think that trace would be clean.


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[sapote]

The picture below is 2000rpm-5500rpm log, yellow is the target, purple is the actual position, and blue is the duty. It increases duty to try to get it to move, which it does slowly.

Without a clear time base then it's hard to say it responded fast or slow. What is the delta time during the purple line ramping up?