MAP + MAF Graph ... Need Advice Please

[MycHo]

Hi Guys,

Here's the problem, a friend has a problem with his Jetta TDI 2000. It keep falling in limp mode and give this code:

17964 - Charge Pressure Control: Negative Deviation
P1556 - 35-10 - - - Intermittent


So we did some testing on his MAP & MAF, see the graphs

We tried a brand new MAF and here's the result:

I don't understand why the 2 graphs of the MAF are the same, it just can't provide enough air ...

So please take a look and let mi know what you think
Thanks a lot
Frank

 

[david_594]

Car is having issues generating boost fast enough as expected by the ECU. Looking at the MAP graphs you can see that it is not reaching max boost till like 3500 RPM which is crazy late for a TDI. It shoudl be achieving it around 2k rpm. One guess might be the VNT actuator is sticking. That would kind of agree with the slow rise in boost.

 

[MycHo]

Thanks I'll give it a look.
And about the MAF, can it be related to the actuator to ?