What are vanos adaptations?

[Arinb12]

I've just retimed my engine, at TDC, I retard both camshafts and the exhaust pin slides in like butter butter, the intake pin has a little bit of resistance but still goes in pretty pretty easy

I assume this means that my timing is nearly perfect, and therefore my vanos would not need to adapt much at all.

I reset my adaptations then went for a drive.

When checking adaptations with the ecuworx tool, my adaptations show the following.



-1.0 inlet (I'd say that's about right for the amount of friction on the pin)

5.0 exhaust. This is where I'm confused. It's definitely not timed 5 degrees out, so I'm wondering why this is the case that it shows this?

What are the adaptations, what are they doing/do they do?

My DIS vanos test passes fine so this is more curiosity than anything else...

[sapote]

Just a guess: Noticed the EX was commanded to move to 0 and 49 (most of the reports shown 48), but the vanos spec to have EX working range is 0 to 45. So maybe the EX max retarded position (hitting the piston cap) is 49, but the operating range is [45 to 0], and so DME used the offset 5 (49 - 45 = 5).

[maupineda]

I think we may have a misconception about vanos adaptations as an indicator of engine timing. Yes, bad timing setup will affect them, but for timing verification you used your timing tools during assembly and the VANOS testing in DIS, Tools32 or ISTA after. So, if you did your timing right during assembly and your VANOS testing confirms there is nothing wrong with engine timing you are good, period.

VANOS adaptations are no different than fuel trims and spark advance/retard, the engine management will adjust based on sensor readouts. My educated guess is that the DME will delay or advance camshaft displacement requests based on what sensors are telling it. For example if the DME says I need 110deg on the intake cam, but it only sees 108 then it will realize it needs more solenoid activation and will request those actions some degrees before or after if it sees the opposite. Based on INPA shown ranges, this can be up to 10deg, now, we all want those values down to zero or as little as possible, but that is our OCD, as long as the DME meets the targets she is happy and makes no difference to it nor to the drivability of the car.

now, my take on what parts can affect those adaptation values are:

- physical engine timing
- internal leaks (seals and valve body state)
- VANOS oil pump
- Pressure accumulator
- Pressure regulator
- Solenoid pack

OP, you made comment on the other thread that you just used one of the pistons from another unit, that is ok, but you mentioned the piston would slide very easily, that is not good and I am surprised you did not change the seals, they are cheap and easy to do and you had the unit apart. Bad decision.

now, if I am honest, your VANOS results are not bad, timing is fine, response times are good, and the only thing I could say is not ideal is your leak on the exhaust side where the cam drifts 3deg, was this the piston that slid very easily perhaps? But again, tolerance is 5 so is fine still.

my leak values are in the 1-2 deg, so my adaptations will be smaller as there is less internal leakage. Also if you have a weak accumulator we could see that the VANOS would take more solenoid activation thus a larger adaptation values, particularly during demanding conditions.

do you have any issue with how the car drives, subjectively and objectively? If nein, leave the old girl alone!!!!!!!

[Arinb12]

I think we may have a misconception about vanos adaptations as an indicator of engine timing. Yes, bad timing setup will affect them, but for timing verification you used your timing tools during assembly and the VANOS testing in DIS, Tools32 or ISTA after. So, if you did your timing right during assembly and your VANOS testing confirms there is nothing wrong with engine timing you are good, period.

VANOS adaptations are no different than fuel trims and spark advance/retard, the engine management will adjust based on sensor readouts. My educated guess is that the DME will delay or advance camshaft displacement requests based on what sensors are telling it. For example if the DME says I need 110deg on the intake cam, but it only sees 108 then it will realize it needs more solenoid activation and will request those actions some degrees before or after if it sees the opposite. Based on INPA shown ranges, this can be up to 10deg, now, we all want those values down to zero or as little as possible, but that is our OCD, as long as the DME meets the targets she is happy and makes no difference to it nor to the drivability of the car.

now, my take on what parts can affect those adaptation values are:

- physical engine timing
- internal leaks (seals and valve body state)
- VANOS oil pump
- Pressure accumulator
- Pressure regulator
- Solenoid pack

OP, you made comment on the other thread that you just used one of the pistons from another unit, that is ok, but you mentioned the piston would slide very easily, that is not good and I am surprised you did not change the seals, they are cheap and easy to do and you had the unit apart. Bad decision.

now, if I am honest, your VANOS results are not bad, timing is fine, response times are good, and the only thing I could say is not ideal is your leak on the exhaust side where the cam drifts 3deg, was this the piston that slid very easily perhaps? But again, tolerance is 5 so is fine still.

my leak values are in the 1-2 deg, so my adaptations will be smaller as there is less internal leakage. Also if you have a weak accumulator we could see that the VANOS would take more solenoid activation thus a larger adaptation values, particularly during demanding conditions.

do you have any issue with how the car drives, subjectively and objectively? If nein, leave the old girl alone!!!!!!!

Thanks, Very informative and makes sense to me.

So the last failure on the other thread (https://nam3forum.com/forums/forum/m...270#post150270)
was down to the solenoid body and solenoid pack. Nothing was wrong with them per se, cleaned and they clicked open with a magnet. All pins on the vanos connector had good continuity showing no solder issues.

What had actually happened was that oil had got into the solenoid electrical connector and was driving it crazy...

Before I realised this I actually tried a few things just to test it all out and rectify, yes it meant putting it all together and opening it all up a number of times.

1st I thought that the issue was that I transferred the piston from my old vanos to the replacement and the seals were already bed to the bore of the old vanos (the exhaust piston and whole unit had new beisan seals with 100 miles on them, there's no bore seal on the exhaust as far as I remember) so I thought that the exhaust bore was thicker on my old vanos and so the seal wasn't as good on the replacement vanos bore with the old piston in place.

So I decided to put the piston back in my old vanos which I knew got through the vanos test but failed on time taken to advance and retard (ms) as well as having low hot oil pressure (60bar); I swapped over the entire oil pump disc assembly, disc, piston caps and springs and the retaining ring too.

Refitted the old original vanos with replacement oil pump parts.

Ran the test. Still failed vanos test on time taken to advance and retard (it lessened but wasn't good enough), BUT also now failed on the leak test in the exhaust piston, so that told me the piston seals had compressed more in the replacement vanos which probably had a tighter bore and now weren't sealing in the old vanos bore. NIGHTMARE.

Did a pressure test. Hot oil was holding at 80bar on the old vanos with replacement vanos pump parts.

This told me definitely the old vanos oil pump, associated parts AND the shaft itself were so worn they were causing my low vanos oil pressure, and subsequent failure of the time taken part of the test.

Then I swapped the replacement oil pump disc, associated parts back to the replacement vanos (original home) and the exhaust piston (originally from old vanos)

Then refitted, took it for a drive and it ran so rubbish, idle low, died on me a few times and just sounded like a bag of crap; ran the vanos test. Results were as in the other thread where it just simply failed at the first hurdle saying it was out of range...

Couldn't think why. Tested vanos solenoid continuity at connection pins again, all was good. Then noticed some oil on the connector plug and knew what the issue was...

Some electrical contact cleaner on vanos connector and the electrical connector plug and ran vanos test, then BAM. Passed

Decided not to renew seals in the replacement vanos until I fail a vanos test. Will probably do one every few months.... Do not want more issues and now am in the it's passed let's not mess with it anymore mode.

It's coming apart once more to drill the disc and then will all go back together and remain that way.

It drives great now and I can really tell where it was down in power before (from the beginning where my mech timing was out and it wasn't adapting - the reason I began this journey, and then even from when I fixed timing but the vanos test failed on timing/low pressure)

Glad it's fixed now

[sapote]

VANOS adaptations are no different than fuel trims and spark advance/retard, the engine management will adjust based on sensor readouts.
!

Needs fuel trim because injected fuel volume is unknown — an opened loop system compared to cams timing which is a closed loop system with known feedback measured angles.

yes, i see the similarities with ignition timing but ignition uses the knock sensors to optimize the spark timing. What does the DME use to set the Vanos adaptation values?