1.4T Turbo problems

[tzaks]

Hello All and thank you for reading through this thread.

I have a GTC with the A14NET engine. My turbo is not building enough boost, I've done some testing that I'll list below, please advise on what to do next as I'm running out of ideas.

Using the OBD II and Torque Pro app I'm monitoring Turbo boost and Intake Manifold Pressure.
I have two solenoid valves as I thought this was the problem. 
With the solenoid connected to the wastegate, the car won't boost more than 4-5 PSI triggering a P0299 (UNDERBOOST)
Without the solenoid connected to the wastegate, the car will boost to 13-16 PSI for a couple of times until encountering a Service Vehicle Soon popup which essentially is a P0234 code (OVERBOOST) 
The MAX PSI for the intake manifold pressure registered was 27 PSI
The MAX PSI for the turbo boost registered was 16 PSI

I've also tried using a Manual Boost Controller (TURBO TEE) and "bypassing" the Solenoid. Same story, boosts a few times and then P0234 comes on limitting the boost to 4-5 PSI. 

Looking at the Workshop Manual it states the following: 
Use the scan tool and compare the manifold absolute pressure (MAP) Sensor parameter to the Boost Pressure Sensor parameter during a WOT acceleration. The readings should be within 20 kPa (2.9 PSI) of each other.

They are not within 2.9 PSI of each other. As mentioned above, max PSI for the Intake manifold pressure was 28 whilst Turbo boost PSI was 15-16 max.

I can hear my turbo spooling, I've adjusted the wastegate to open later but none of this worked. I've also checked the "nipple" inside the intake manifold and it's there. 

Can you please share your thoughts? I want to get it working properly but I don't want to buy a new turbo and end up having the same problem. A mechanic told me it's not the turbo whilst another mechanic told me it's the turbo. 

Many thanks!

[Rusty2009]

Best thing to do is take the turbo off and get the turbo tested by a turbo shop.

I was having issues like you, my turbo was 100% fine, in the end I just replaced the 2 inter-cooler pipes and and all the vac hoses no more issues so far.

[tzaks]

Thank you, I'll remove the turbo and get it inspected.