diff --git a/src/calculate/optimize/fit_coeffs.py b/src/calculate/optimize/fit_coeffs.py
index b443daf..4343abc 100644
--- a/src/calculate/optimize/fit_coeffs.py
+++ b/src/calculate/optimize/fit_coeffs.py
@@ -30,7 +30,7 @@
 
 #falloff_bnds = np.array([[1E-12, 1E-12, 0.1], [1E30, 1E30, 1]])
 #falloff_bnds[:,0:2] = np.log(falloff_bnds[:,0:2]) # ln(k_0), ln(k_inf), Fcent
-falloff_bnds = np.log([[1E-6, 1E-6, 1E-3], [1E25, 1E25, 1]])  # ln(k_0), ln(k_inf), ln(Fcent)
+falloff_bnds = np.log([[1E-6, 1E-6, 0.1], [1E30, 1E30, 1]])  # ln(k_0), ln(k_inf), ln(Fcent)
 
 troe_falloff_0 = [[0.6, 200, 600, 1200],            # (0, 0, 0)
                                                     # (0, 0, 1)
@@ -571,7 +571,7 @@ def LPL_HPL_Fcent(self):    # CURRENTLY A KNOWN BUG IF FULL LIMIT IS HELD CONSTA
                    #{'algorithm': nlopt.LN_COBYLA,   'xtol_rel': 1E-2, 'ftol_rel': 1E-2, 
                    #                                 'initial_step': 1E-3, 'max_eval': 500},
                    #{'algorithm': nlopt.LN_COBYLA,   'xtol_rel': 1E-2, 'ftol_rel': 1E-2, 
-                   #                                 'initial_step': 1E-4, 'max_eval': 1000} # LN_COBYLA
+                   #                                 'initial_step': 1E-4, 'max_eval': 500} # LN_COBYLA
                   ]
 
         # set scipy curve-fit loss
diff --git a/src/calculate/optimize/mech_optimize.py b/src/calculate/optimize/mech_optimize.py
index e629b71..82d77b2 100644
--- a/src/calculate/optimize/mech_optimize.py
+++ b/src/calculate/optimize/mech_optimize.py
@@ -185,7 +185,7 @@ def _set_coef_opt(self):
 
         return coef_opt                    
     
-    def _set_rxn_coef_opt(self, min_T_range=1000, min_P_range_factor=2):
+    def _set_rxn_coef_opt(self, min_T_range=1500, min_P_range_factor=3):
         mech = self.parent.mech
         rxn_coef_opt = []
         for coef in self.coef_opt: