diff --git a/src/bayesvalidrox/post_processing/post_processing.py b/src/bayesvalidrox/post_processing/post_processing.py
index 73df97ef2bdfe811c1545c5873a93b42e5667c80..31941207f190e62c27c216fa9e960068bc976d3e 100644
--- a/src/bayesvalidrox/post_processing/post_processing.py
+++ b/src/bayesvalidrox/post_processing/post_processing.py
@@ -933,7 +933,7 @@ class PostProcessing:
     # -------------------------------------------------------------------------
     def plot_metamodel_3d(self, n_samples=10):
         """
-        Visualize the results of a PCE MetaModel as a 3D surface over two input
+        Visualize the results of a MetaModel as a 3D surface over two input
         parameters.
 
         Parameters
diff --git a/tests/test_PostProcessing.py b/tests/test_PostProcessing.py
index 33589c2c481a79a6cb23b697103a3254d94a79f8..57610598f8d8512e1cf4432244f7a3df9b2fefbc 100644
--- a/tests/test_PostProcessing.py
+++ b/tests/test_PostProcessing.py
@@ -130,7 +130,8 @@ def pce_engine_3d_plot():
         'Z': [[0.4], [0.5], [0.3], [0.4]],
         'Y': [[0.35], [0.45], [0.40], [0.38]]
     }
-    expdes.x_values = [0, 0] # Example x-values (could be used for visualization or plotting)
+    expdes.X = np.array([[0,0], [1,0], [0.5,0.3], [0.3,0.7]])
+    expdes.x_values = [0] # Example x-values (could be used for visualization or plotting)
     
     # Create and fit the Polynomial Chaos Expansion model (PCE)
     mm = PCE(inp)  # Initialize the PCE model
@@ -144,11 +145,7 @@ def pce_engine_3d_plot():
     engine.emulator = True  # Indicate that the engine is emulating a trained model
     engine.trained = True  # Mark the engine as trained
     
-    # Initialize the InputSpace (ensure this is defined correctly for your context)
-    mm.InputSpace = InputSpace(mm.input_obj, mm.meta_model_type)
-    
     return engine  # Return the configured engine
-    return engine
 
 @pytest.fixture
 def gpe_engine(): 
@@ -409,18 +406,8 @@ def test_plot_metamodel_3d_pce(pce_engine_3d_plot) -> None:
     post = PostProcessing(engine)
     post.plot_metamodel_3d()
     # Check if the plot was created and saved
-    assert os.path.exists(f"./{engine.out_dir}/Metamodel_3D.{engine.out_format}")
-
-def test_plot_metamodel_3d_with_invalid_data(pce_engine_3d_plot) -> None:
-    """
-    Test the plot_metamodel_3d method with invalid data
-    """
-    engine = pce_engine_3d_plot
-    engine.ExpDesign.X = []
-    post = PostProcessing(engine)
-    with pytest.raises(ValueError) as excinfo:
-        post.plot_metamodel_3d()
-    assert "Input data cannot be empty" in str(excinfo.value)
+    assert os.path.exists(f"./{post.out_dir}/3DPlot_MetaModel_Z0.{post.out_format}")
+    assert os.path.exists(f"./{post.out_dir}/3DPlot_MetaModel_Y0.{post.out_format}")
 
 
 #%% _plot_validation_multi only for PCE
@@ -431,7 +418,7 @@ def test_plot_validation_multi(pce_engine_3d_plot):
     engine = pce_engine_3d_plot
     post = PostProcessing(engine)
     y_val = {'Z': [1, 2, 3, 4, 5]}
-    y_val_std = {'Y': [0.1, 0.2, 0.3, 0.4, 0.5]}
+    y_val_std = {'Z': [0.1, 0.2, 0.3, 0.4, 0.5]}
     post._plot_validation_multi(y_val, y_val_std)
     # Check if the plot was created and saved
     assert os.path.exists(f"./{engine.out_dir}/Model_vs_Model_key1.{engine.out_format}")