!!! z4 no any code no power !!!

[ph001]

It does just look like a lack of boost as you say. If it was in limp home mode you would definitely have engine management light on and code stored.

I don’t really know enough about the 2.0l to say how the waste gate actuator is controlled but maybe this is where I would start. Also, how is boost pressure measured by the ecu? I would assume with some kind of MAP (manifold absolute pressure) sensor. If the sensor is reporting wrong value then ecu thinks it is doing full boost when it isn’t????

[enuff_zed]

Ok, this is a really random guess but....................
As previously discussed on this forum, some of the N20s had a pneumatic operated waste gate and others had an electronically operated one.
I have no idea exactly what the physical differences may be, but are you sure you have the correct type for your car.
As I recall, it was the later ones that switched to an electrically operated one?

[abdullah]

Ok, this is a really random guess but....................
As previously discussed on this forum, some of the N20s had a pneumatic operated waste gate and others had an electronically operated one.
I have no idea exactly what the physical differences may be, but are you sure you have the correct type for your car.
As I recall, it was the later ones that switched to an electrically operated one?

my waste valve is electronic. vacuum pump brake and exhaust flap opening and closing work. but my vacuum pump is constantly leaving oil in the faulty engine cover. but this does not affect the car going because wastgate is electronic, not solenoid.

[enuff_zed]

Ok, this is a really random guess but....................
As previously discussed on this forum, some of the N20s had a pneumatic operated waste gate and others had an electronically operated one.
I have no idea exactly what the physical differences may be, but are you sure you have the correct type for your car.
As I recall, it was the later ones that switched to an electrically operated one?

my waste valve is electronic. vacuum pump brake and exhaust flap opening and closing work. but my vacuum pump is constantly leaving oil in the faulty engine cover. but this does not affect the car going because wastgate is electronic, not solenoid.

Ok, rules out one other possibility then.

[ph001]

What is normal boost pressure for the N20? You say that the ECU is only demanding 0.5bar, but how do you know this exactly? Have you actually seen any live data on boost pressure?

[abdullah]

What is normal boost pressure for the N20? You say that the ECU is only demanding 0.5bar, but how do you know this exactly? Have you actually seen any live data on boost pressure?

we monitored the real road test with the computer connected to the car. We checked all values such as calculated and actual crank speed, torque, fuel suction, air suction. All values correspond exactly to the request and calculation of the ECU. but here the ECU turbo pressure does not exceed 0.5 bar request, the pedal map I know and in sports mode, it should request pressure between 0.9-1.1 bar. We did the wastgate on / off manual test from the computer and it gave no problems.

[ori]

Maybe it can’t reach a higher boost because of a leak?

[Smartbear]

Maybe it can’t reach a higher boost because of a leak?

Turbo isn’t being asked to boost any higher than 0.5bar, it can’t be a leak
Rob

[abdullah]

Maybe it can’t reach a higher boost because of a leak?

Turbo isn’t being asked to boost any higher than 0.5bar, it can’t be a leak
Rob

Just like you said, we have already kept all the lines to compression, zero leakage. ECU not requesting boost.

[ph001]

Does the E89 have vacuum controlled exhaust valve? I know on other bmw models that if you get a leak on the vacuum line there then it affects the wastegate actuator and you get low boost.

The dump valve is another area to consider if it’s not part of the turbo assembly (in which case it would be new anyway if the turbo is new).

I think the only way you are going to get to the bottom of this is to put something like a JB4 on it, then you know the ecu map is good. Also has the advantage of comprehensive data logging.

I’m still not sure how the OP has concluded the ecu is only demanding 0.5bar. It’s easy enough to measure 0.5bar actual boost pressure but that’s not to say that is all that is being demanded.

[R.E92]

Yes, seems to be a lack of procedure here. This should be an easy issue to sort but it sounds like OP is just changing random parts in the hope something fixes it.

Target boost of 0.5bar would be 7PSI, the N20 should run at around 18PSI target from memory.

If the target boost is truly 7PSI and there's no error codes logged in ISTA then you almost certainly have a mismatch of DME software. This isn't a limp mode, rather a powerclass mismatch which won't trigger any codes, just puts the car into a low power mode and keeps the wastegates open.

If target boost is normal but actual boost is low you would certainly see a low charge pressure error code on the dash.

Blocked cats can give all the symptoms you've stated so that's another possibility. Nobody in their right mind would still have primary cats fitted anyway so no harm in getting them removed if they are an issue.

I wouldn't throw money away on a JB4 just for logging, there's a free program called TestO that will run on a laptop. You can also use Bimmergeeks ProTool for logging engine data which would be my chosen solution.

[abdullah]

Yes, seems to be a lack of procedure here. This should be an easy issue to sort but it sounds like OP is just changing random parts in the hope something fixes it.

Target boost of 0.5bar would be 7PSI, the N20 should run at around 18PSI target from memory.

If the target boost is truly 7PSI and there's no error codes logged in ISTA then you almost certainly have a mismatch of DME software. This isn't a limp mode, rather a powerclass mismatch which won't trigger any codes, just puts the car into a low power mode and keeps the wastegates open.

If target boost is normal but actual boost is low you would certainly see a low charge pressure error code on the dash.

Blocked cats can give all the symptoms you've stated so that's another possibility. Nobody in their right mind would still have primary cats fitted anyway so no harm in getting them removed if they are an issue.

I wouldn't throw money away on a JB4 just for logging, there's a free program called TestO that will run on a laptop. You can also use Bimmergeeks ProTool for logging engine data which would be my chosen solution.

I went to pick up the car today. but the master said that wastgate opens itself after 1500 rpm in the tests. I cannot determine why he opened it, he said.

[enuff_zed]

So does that suggest the car thinks it is over-boosting, and opens the waste gate to dump it?
Could that be due to a boost sensor reading incorrectly?

Which I just realised is the question ph001 raised earlier.

[Raj_UK]

Any update on this? I was finding it really interesting!

[abdullah]

Any update on this? I was finding it really interesting!

unfortunately we canceled the oxygen sensor and tried it. We did a DME reset. We tried a new brain. We did a software copy from another e89. There was no improvement. my ridiculous car goes to 100 in 11 seconds and there is no fault code and our trials were inconclusive. .