VANOS apparently disabled

[mrscalex]

My 3.0 Z3 has been sluggish ever since I put it on the road after buying as a project. It doesn't feel that much quicker than a 2.2 and is miles off the 2 other 3.0s I've driven.

It does have an exhaust camshaft error but I've had this on a 2.2 with no apparent loss in performance. Anyhow I have a replacement sensor on the way.

I've checked the fuel trims and these are normal so I don't suspect air leaks.

I've then looked at the VANOS readouts in INPA. If the actual VANOS position lags the target position set by the DME then failing VANOS seals are suspected. But to be fair it's probably a no brainer to change the VANOS seals anyway. I guess I was intrigued to see the data in INPA to back it up.

But replacing the seals is not the point. The target position set by the DME for both inlet and exhaust is fixed and never varies which is clearly not correct. 126 for inlet and -105 for exhaust. That's not just static with INPA as I know the timing is load dependant not just RPM dependant. I setup testo (data logger) and on a 10 mile journey neither changed.

I think it's unlikely the tools are reporting wrongly. Everything else about them works. I'm new to testo but I had that logging everything else correctly.

So the question is - does the DME disable the VANOS on both camshafts if either camshaft sensor is faulty? I guess it makes sense...

 

[Redline]

It would make sense for the software to back out of requesting changes if it registers no impact of changes made previously. It probably also makes changes to the fuelling too at the same time That said, I’d expect a permanent EML light on the dashboard in those circumstances. I’d also expect multiple specific codes to be raised for abnormal operation. So, the evidence is at odds with what you’re seeing? Could be something else but try the sensor change first, but, with the expectation the problem may lie elsewhere.

 

[mrscalex]

There is a second error - on the O2 sensors. Haven't got the details to hand but my view was it appeared to be related to the exhaust camshaft sensor. No EML dash warning though.

Otherwise there are no other errors which I guess I found a bit strange hence the post. But logic says knackered camshaft sensor and the VANOS puts the camshafts into a fixed configuation.

 

[mrscalex]

@Pingu or @Murray Wall any words of wisdom here please as I know this is your areas of expertise. My resolution approach is clear - replace the exhaust camshaft sensor. But I like to know how these things work, ie is VANOS in fixed config due to sensor, why no error codes, anything else likely to be wrong

Btw I've been reviewing this thread you guys started/feature in as motivation to get up and running with TestO - great tool.

https://zroadster.org/threads/testo-datalogger-what-do-you-think.18350/

 

[Pingu]

Everything that you guessed in the OP make sense and I agree with your thinking.

The only top tip that I have is to only replace the sensors with OEM ones. When it comes to sensors, if it's broke, it won't work. The problem with aftermarket sensors are well documented and they are cheap for a reason.

Replace the solenoid seals with VITON.

 

[mrscalex]

Everything that you guessed in the OP make sense and I agree with your thinking.

The only top tip that I have is to only replace the sensors with OEM ones. When it comes to sensors, if it's broke, it won't work. The problem with aftermarket sensors are well documented and they are cheap for a reason.

Replace the solenoid seals with VITON.

Thanks @Pingu

I've only ever used OEM. Inlet I use new BMW - I keep an eye on ebay and buy if I see one cheap and keep until needed. Exhaust I tend to buy second-hand. I've done well at £15 a time so far from the same dismantler source.

One more thing you may know. Are the sensors binary in their state of function? ie working or bust? Or are there shades of grey in-between whereby there are no faults reported but they are starting to go past their best?

 

[mrscalex]

I have a nice supply of VITON seals for most common purposes. Took me flippin ages finding the right size for everything but I have all the most common stuff now.

 

[NZ00Z3]

I agree with changing the exhaust cam shaft sensor.

Its been a while since I have worked on VANOS and TestO but I recall a problem with logging. There are three VANOS variables to log, Reference, Actual and Target. I came to the conclusion that in TestO, Two had been transposed in the programs definitions. I think it was Reference and Actual. Your results of the actual values not moving may be because TestO was looking at the reference value, which does not move. I suggest that you log all three variables to see what is happening.

 

[NZ00Z3]

The first chart (LL33005) is of a working VANOS on a very low mile 3.0 L Z3, so you can see what it should look like.

The second chart (LG73383) is of 2.0L Z3 with 100,000 miles on the clock before seal replacement. Still not bad but here was a noticeable performance improvement after the seal replacement. Didn't do a post repair logging. Testing done with a stationary car, just reving up the engine.

 

[mrscalex]

I agree with changing the exhaust cam shaft sensor.

Its been a while since I have worked on VANOS and TestO but I recall a problem with logging. There are three VANOS variables to log, Reference, Actual and Target. I came to the conclusion that in TestO, Two had been transposed in the programs definitions. I think it was Reference and Actual. Your results of the actual values not moving may be because TestO was looking at the reference value, which does not move. I suggest that you log all three variables to see what is happening.

You may be correct about the transposition - I don't know. But I did log all 3 values (well 4) and they all stayed static as follows. Nothing changed from this over a 20 min drive.

Blue target obviously hiding behind actual as they are the same.

 

[mrscalex]

The first chart (LL33005) is of a working VANOS on a very low mile 3.0 L Z3, so you can see what it should look like.

The second chart (LG73383) is of 2.0L Z3 with 100,000 miles on the clock before seal replacement. Still not bad but here was a noticeable performance improvement after the seal replacement. Didn't do a post repair logging. Testing done with a stationary car, just reving up the engine.

Great to have those graphs thanks. The VANOS seals will get done anyway but I like to have all the background knowledge too.

 

[Pingu]

One more thing you may know. Are the sensors binary in their state of function? ie working or bust? Or are there shades of grey in-between whereby there are no faults reported but they are starting to go past their best?

That's my experience. I've never had a sensor fail in a gradual way other than through corrosion adding resistance.

All the sensors that have failed in my experience have failed instantaneously. They can be intermittent if the connectors are dodgy. They can give a permanently false reading (not zero) if the connections are corroded or dirty.

 

[Mario]

Robert - there is a function on DIS that let's you perform a test on the vanos wihout having to drive the car around, the software cycles the vanos between the two extremes of the adjustment range and tests how long it takes to get the actual position reach the target position, I guess that will give you also some indication on what's going on because that's a manual instruction to the DME to perform the changes and I guess it will ignore any other error or variables.

 

[mrscalex]

Robert - there is a function on DIS that let's you perform a test on the vanos wihout having to drive the car around, the software cycles the vanos between the two extremes of the adjustment range and tests how long it takes to get the actual position reach the target position, I guess that will give you also some indication on what's going on because that's a manual instruction to the DME to perform the changes and I guess it will ignore any other error or variables.

Very good thank you. Never had much luck getting DIS to work but will certainly be trying that out maybe on a fresh installation.

 

[Mario]

Took me a few tries but I managed to get it to work in the end, no idea how but after I got it working I made 3 clones of the hard drive lol if you get stuck let me know and I will try help

 

[mrscalex]

Exhaust camshaft sensor changed. All errors gone.

Took a while for the VANOS to kick back into life but that might just have been while the engine was warming up.

The plot below is a 0-60 run. There's some question over whether TestO labels actual/target correctly. But I think the version I have does and I've plotted as it records the data. @Pingu & @Murray Wall I know you're the data interpretation specialists This was done at a maximum sampling of 50Hz. Does this show enough lag you'd want to run off and rebuild the VANOS? And do you agree the target & actual labelling is the correct way round?

 

[NZ00Z3]

Your labels are correct. Target leads Actual.

I would replace the VANOS seals.

Well done with the logging.

 

[mrscalex]

Your labels are correct. Target leads Actual.

I would replace the VANOS seals.

Well done with the logging.

Thank you. I was really pleased to get TestO running. Great tool and the nice thing is if you have INPA running then TestO should run fine too. Although I'm using the stand-alone version. Great tool.