M52B28TU - VANOS operation problem?

[PokiBG]

Dear BMW friends,

I am struggling with a M52B28TU engine inserted in my E30.
Gearbox is Getrag 220 from E36, lightened flywheel and diff ratio 2.93.

Some things were replaced on the engine like bearings, timing chain, piston rings and few other things as well..
The VANOS unit was completely removed and re-installed with a vanos toolkit.

It feels like the engine is not running the way it is supposed to.

Acceleration is not optimal, fuel consuption is a bit high and max speed is about 220 km/h - goes to about 5800 rpm on 5th gear and just cant push any more..

Recently I did some logging of the ECU with TestO and some things are bothering me.
It seems that the VANOS unit cannot reach the target degree that the ECU wants.

Intake camshaft:

At some point, the ECU targets 120 degrees for the intake (which means camshaft default position), but the actual position wont reach more than 118 degrees, most of the time its stuck at 117 degrees.
I know there is some response time for the VANOS to achieve what the ECU wants, but this behavior is noticed when the ECU targets 120 degree continuously for like 3-4 seconds but wont actually reach them.
I couldn't see any point where the ECU reports 120 degrees other than having the car on START and enigne not running.

I know its ok to have some deviation but 3 degrees - especially towards default position - is that normal?

Maybe the VANOS wasn't set up correctly when reinstalled? (I didn't do the job, so I can't be sure).
Or maybe the seals are worn out - but in my opinion bad seals would lead to bad response time, not to total inability to reach certain degree.

Exhaust camshaft:

Here first thing that made me wonder was actual exhaust camshaft position of -105.375 at some of the updates. (when theoritically minimum degree should be -105).
I suppose that was some incorrect value given by the camshaft sensor rather than problem with the vanos itself.

The other thing was again inability to reach certain target, but here it was not only towards default position of -105.

For example:
Target: -105.00 | Actual: -103.5 -- not that often
Target: -103.5 | Actual: -105.0 -- more often

But at some point, vanos was able to achieve what the ECU wanted, so here its more likely to be due to bad seals, smugged line or something.

So for a 20 min of driving time, total Target to Actual degrees deviation is as follows:

Intake Camshaft Deviation: 2.33 degrees
Exhaust Camshaft Deviation: 1.55 degrees

As I pointed, this deviation means nothing actually, because when camshaft is at certain degree and ECU wants to change that, there is a bit of latency before that happens.
So measuring deviation at an given point in time is not reliable information.
Anyway just for information I calculated that as well.

And lastly I would like to ask if this maximum values for Engine Load and Air Mass seem correct for this engine M52B28TU.
Please share your maximum values you have reached.

Maximum engine load @ 4854 RPM: 543.862 mg/stroke
Maximum air mass @ 6337 RPM: 506.25 kg/h

Both were reached at Wide Open Throttle (WOT) and engine operating temperature ~ 95 degrees C.
Intake air temp about 38 degrees and altitude 500m above sea level.

I am suspecting dirty MAF sensor - maybe that is contributing to the bad performance, although O2 sensors dont seem to indicate fuel/air mixture lean conditions..

Looking forward for your opinions.

Best regards.

p.s. I can also attach the full 20 min log if anyone would like to analyze it - I would be very grateful.

[dworthy]

Welcome to the Forum!

I do believe that VANOS affects the lower end power more than the top end normally. Do you get a rattle at or around 2500 rpm? It very well can be that the seals are worn, and bleeding the pressure out thus not allowing it to push the cams around as needed. Do you have any codes related to VANOS like cam positioning, ect.

With that thought in mind, I would also look at two thing:

1) Timing
2) DISA

What are you using to read all this stuff? I like INPA as it gives you are "green" and "red" zones so you know where it should be.

[PokiBG]

After cleaning the MAF things improved.
Acceleration seems better - especially at the high end.
Haven't tested the max speed and consumption yet.

Just FYI after cleaning the MAF these are the maximum results for Load and Air Mass after a short ride.

Maximum engine load @ 4184 RPM: 605.716 mg/stroke
Maximum air mass @ 6402 RPM: 590.5 kg/h

Anyway the VANOS is still acting the same.

Yes, the VANOS affects middle and lower end, but should return camshafts into default
positions at high RPMs in order to provide full power there.

I don't hear rattling sounds from the unit but vanos degrades with time.
So not hearing noises yet doesn't mean that the vanos is working properly.

So if the ECU can't get the desired degrees of the shafts (or don't reach them fast enough),
engine performance is not optimal.

I am using TestO for logging the data..
INPA is showing the same results but doesn't have a warning for the VANOS data.
Also the ECU give no errors about the vanos.

I tried running intake shaft vanos test through INPA which started decreasing the degrees slowly and
was able to reach 80 degrees which is the lower limit by design for this enigne.

So can anyone tell if average of 2.3 degrees deviation between Target and Actual intake camshaft position normal?
Can anyone provide such calculation of their VANOS after rebuild (changed seals)?

[dworthy]

No, I don't think that having that many degrees out can be normal.

I would start with replacing the 4 O-rings, and see if that helps with the reaction.

In INPA how does the Rough running look? Should be under the DME side, and IIRC test 2?

Once you get 10 posts on the forum, it will allow you to upload directly to the Forum.

Do you have a Google account? You could put it on the Google drive and then share the link here so we can take a look at the logs.

[PokiBG]

Here are the logs.

Before cleaning MAF.
https://drive.google.com/file/d/0B6b...ew?usp=sharing

After cleaning MAF
https://drive.google.com/file/d/0B6b...ew?usp=sharing

Rough values seen on INPA seem to be fine.
Some of the cylinders go up to almost 1 sometimes especially when engine is cold.
TestO values sometimes are below 0?

I am not sure which test you are pointing, but I am using INPA v.5 and all other tests for the vanos gave some kind of errors.