Boost Pressure Too Late?

Good morning, everyone.

Please find the log file attached.
Sorry about the timestamp mess... I can't seem to get it right. The maximum value was 6.41 seconds.


Am I mistaken, or is the turbocharger pressure building up too late in my car?
(Side note: The AGR (Abgasrückführung) system is defective...)

Thank you for your opinions.

Best regards,
Wool.

Hello Wolle,

Yes, far too late. Standard error with the AEL (air intake manifold): a crack on the underside of the connection rubber between the aluminum intake manifold and the intercooler pipe.

Best regards, Rainer.

Hello Rainer,


Thank you for your tip. That is indeed a common mistake.

I also suspected the pressure hose and had already checked it, at least at the top, where it's prone to breaking. It looks fine visually and isn't oily, but it's quite porous overall. You can see it quite clearly if you bend it a bit. Since I'll definitely have to replace the hose eventually, I'll do it at this opportunity. It's as old as the car, and I probably won't have to replace it again after this.

I'll update you here with the result once I've replaced the hose.


Edit: I'm also going to make two blanking plugs that I can use to seal the hoses from the charger to the intercooler and from the intercooler to the intake manifold, and I'll install a valve in one of the plugs. That's a quick job. Then I can pressurize the system and test to see if everything else is okay.


Best regards,
Wool.

Hello everyone,


Okay, so... I've already pressure-tested the hoses and the cooling system, and I can confidently say that everything is leak-free.

"If I disconnect the pressure hose from the intercooler to the intake manifold and then start the engine, I don't feel any airflow, which probably means that the turbocharger isn't spinning at idle..."
Shouldn't it at least rotate a little and create a noticeable draft?
I read this somewhere before.

Okay, here's a snippet from a log file of the MWB11:
Please excuse the less-than-perfect formatting; I still haven't figured out how to handle the timestamp issue.

Here, idling with a brief burst of acceleration.

U/min Target Pressure Actual Pressure
756 1275.0 979.2
756 1275.0 979.2
778 1275.0 979.2
1166 1326.0 979.2
2419 1509.6 989.4
1814 1519.8 1030.2
1166 1489.2 1020.0
778 1377.0 1009.8
713 1305.6 999.6
713 1285.2 989.4
734 1285.2 989.4
756 1275.0 979.2
756 1275.0 979.2
756 1275.0 979.2

And here, with the machine stationary:

U/min Target Pressure Actual Pressure N75
0 683.4 999.6 94.9
0 683.4 999.6 94.9
0 683.4 999.6 94.9
0 683.4 999.6 94.9


I'm going to do another test with an open exhaust system (catalytic converter unscrewed)... let's see if it makes a difference... Maybe it's just sealed properly.

But what would you say about these values? Don't they seem to be quite far apart?

Thank you for your effort, and best regards.
Wool.

Hi,

Is no boost being generated at all? Is the turbocharger definitely okay, and is the wastegate actually closing properly?

Best regards, Rainer.

Hello Rainer,

Unfortunately, I can't really answer that question.
I now suspect that the loader (still the first one) has seen its best days.

I still need to check if the wastegate is closing properly. However, access to it is very difficult with the current setup, which is why I've been putting it off so far.
Let's see how I can do this.
The impeller shaft is also quite difficult to turn by hand. However, I don't have anything to compare it to, so I can't say whether that's normal.

Today, I wanted to remove the catalytic converter and check if it's working properly.
That's the last thing, besides the wastegate, that I haven't done yet these days.

If that doesn't help either, then it's probably, as you seem to suspect, the turbocharger or the wastegate.

"Once I have a result, I will get in touch."

Best regards,
Wool.

wolle wrote:

The loading coil shaft can also be difficult to turn by hand.

I'd say you've found the error, and it should turn easily now.

Hello everyone,

Here's some more feedback...

To be absolutely sure, I removed the N75 valve from the control line for the wastegate and connected the coolant supply hose directly to the wastegate. This should cause the boost pressure to increase significantly due to the lack of regulation. Furthermore, I installed an empty catalytic converter, but only for testing purposes.
Result: The boost pressure remains the same. In my opinion, the wastegate must be leaking.
I re-ran the shaft rotation test on the loader arm with the machine quite warm...ouch, hot, hot, hot... It's easier to turn than when the machine is almost cold (obviously), but it's not optimal, and a 1mm amount of play is probably not ideal either.


Well... it seems I'm going to have to get a new or replacement charger.
Now I just need to find a good, affordable source... Then it's time to just close my eyes and go for it.
Feel free to contact me via private message for more information.

Thank you.
I wish you all a lovely day.

Best regards,
Wool.