DIS VANOS test results leak help

[ac427]

I ran the DIS VANOS test twice today and got the results below. The first test failed but the second test, around 20 minutes later, passed.

The exhaust side is leaking. Is this usually faulty valves in the valve block or the sealing plate between the valve block and the VANOS unit?

Do the other results look ok?


First test results:
Reached position, inlet late: 58.6 °KW
Reached position, inlet early: -1.5 °KW
Reached position, outlet early: -4 °KW
Reached position, outlet late: 44.6 °KW

Deviation leak test inlet: 2.5 °KW
Deviation leak test outlet: 5.1 °KW

VANOS system outlet leaking

Procedure:
1. replace VANOS solenoid valve set
2. repeat function test
3. if error occurs more frequently (>50%),

Early adjustment time inlet: 209ms
Late adjustment time inlet: 200ms
Early adjustment time outlet: 195ms
Late adjustment time outlet: 217ms



Second test results:
Reached position, inlet late 58.4 °KW
Reached position, inlet early -1.6 °KW
Reached position, outlet early -3.9 °KW
Reached position, outlet late 47 °KW

Deviation leak test inlet 1.4 °KW
Outlet leak test deviation 3.9 °KW

Early adjustment time inlet: 224ms
Late adjustment time inlet: 229ms
Early adjustment time outlet: 235ms
Late adjustment time outlet: 228ms

All actual values correspond to the setpoint values.
VANOS system in order.

[Stilt]

I would go ahead and do the seals for the pistons and the sealing plate.


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[ac427]

Thanks, Beisan seals are installed throughout and the vanos unit has done several thousand miles. It seems that there is less leakage as the temperature increases.

[bmwfnatic]

These are good results in my opinion, if there are no other problems I would probably leave it alone.

If you look at the Tool32 VANOS thread on here nearly all of them fail the leakdown part of the test, my suspicion is that this is due to a worn out valve block, I have a brand new one to confirm that suspicion at some point.

[ac427]

These are good results in my opinion, if there are no other problems I would probably leave it alone.

If you look at the Tool32 VANOS thread on here nearly all of them fail the leakdown part of the test, my suspicion is that this is due to a worn out valve block, I have a brand new one to confirm that suspicion at some point.

Thanks. I agree but I get very rough running issues when starting the engine in cold weather. I eventually got a "Misfire on cylinder 1" code. The next morning once the outside temperature had risen. The car started and ran better but still was rough for a few minutes.

I am presuming this is related to the vanos exhaust leak. Once warm starting is no longer an issue.

[sapote]

Thanks. I get very rough running issues when starting the engine in the cold weather. I eventually got a "Misfire on cylinder 1" code. The next morning once the outside temperature had risen. The car started and ran better but still was rough for a few minutes.

I am presuming this is related to the vanos exhaust leak. Once warm starting is no longer an issue.

Read the DME codes.
Was the DIS vanos test performed in similar cold condition (rough engine running)?

If vanos test passed then it should not cuase the rough cold running.

[ac427]

Read the DME codes.
Was the DIS vanos test performed in similar cold condition (rough engine running)?

If vanos test passed then it should not cuase the rough cold running.

The tests were performed roughly 20 to 30 minutes apart. So once the engine had warmed up sbit more the there the leak had reduced enough to pass the test.

Also, the DIS Vanos test has to be performed when the engine temperature has reached 85⁰C (185⁰F). It was actually at 84⁰C (183⁰F) when I got DIS running.

The DME can trim out the rough running after a 15 seconds or so from a cold start if the outside temperature is warm.

On the night when I got the misfire on cylinder 1 error code. The outside temperature was around 3⁰C (37⁰F).

There are currently no error codes on the DME.

[maupineda]

These are good results in my opinion, if there are no other problems I would probably leave it alone.

If you look at the Tool32 VANOS thread on here nearly all of them fail the leakdown part of the test, my suspicion is that this is due to a worn out valve block, I have a brand new one to confirm that suspicion at some point.

I do not think the leak values are "good". they should be less than 5deg. second time it passed, but not with enough margin IMO, I agree it could be the valve body, not necessarily the seals, I think if seals were bad, the response time may be lower and his values are good.

[bmwfnatic]

I do not think the leak values are "good". they should be less than 5deg. second time it passed, but not with enough margin IMO, I agree it could be the valve body, not necessarily the seals, I think if seals were bad, the response time may be lower and his values are good.

To my knowledge the VANOS doesn’t continuously actuate, it commands a cam in a certain position and then expects it to stay there indefinitely, until it commands another position, so I suppose the ‘leak’ part of the test does exactly this, command a position, and then wait to see if it can stay there.

I said it was okay because the numbers I am seeing do not warrant taking apart the VANOS again, are they perfect? No, I guess not, but I don’t want to send OP on a wild goose chase replacing more stuff on his VANOS, while his problem likely lies elsewhere.

[maupineda]

To my knowledge the VANOS doesn’t continuously actuate, it commands a cam in a certain position and then expects it to stay there indefinitely, until it commands another position, so I suppose the ‘leak’ part of the test does exactly this, command a position, and then wait to see if it can stay there.

I said it was okay because the numbers I am seeing do not warrant taking apart the VANOS again, are they perfect? No, I guess not, but I don’t want to send OP on a wild goose chase replacing more stuff on his VANOS, while his problem likely lies elsewhere.

Conceptually yes, but since the system monitors the cam position via the cam / crank position sensors, if it sees drift, it will command a different PWM signal to maintain the desired position, to your point, the engine is rarely in steady state and the VANOS is constantly commanding different positions anyway. that said, you do not want a leaky system as that will just make harder to achieve target value. if it was me, I would try to fix it, if the seals are fresh, then the valve body or pressure regulator would be the next element to look at. but i do not think this is why he has rough running when cold.

[ac427]

I'm thinking the rough running when cold could be because the leak is worse at lower temperatures. So the system cannot get the exhaust cam to or maintain the desired position, for warm up from cold.

Previously. I have cleaned the valve blocks in petrol, in an ultrasonic tank, whilst operating the solenoid valves.

It did get an well respected independent garage do the complete vanos unit swap.

[sapote]

If there’s no vanos error codes then I don’t think the rough idling is related to it.