diff --git a/cdm/core/src/main/java/ucar/nc2/ft2/coverage/CoordAxisHelper.java b/cdm/core/src/main/java/ucar/nc2/ft2/coverage/CoordAxisHelper.java
index 76dceedb7a..bb19bffb9a 100644
--- a/cdm/core/src/main/java/ucar/nc2/ft2/coverage/CoordAxisHelper.java
+++ b/cdm/core/src/main/java/ucar/nc2/ft2/coverage/CoordAxisHelper.java
@@ -11,7 +11,7 @@
 import ucar.nc2.constants.AxisType;
 import ucar.nc2.time.CalendarDate;
 import ucar.nc2.time.CalendarDateRange;
-import ucar.nc2.util.Misc;
+
 import javax.annotation.Nonnull;
 import java.util.Arrays;
 import ucar.nc2.util.Optional;
@@ -25,6 +25,8 @@
 class CoordAxisHelper {
   private final CoverageCoordAxis1D axis;
 
+  private static final int MULTIPLE_HITS = -2;
+
   CoordAxisHelper(CoverageCoordAxis1D axis) {
     this.axis = axis;
   }
@@ -201,16 +203,16 @@ else if (upperIndex > axis.getCoordEdgeLast())
   }
 
   // same contract as findCoordElement(); in addition, -1 is returned when the target is not contained in any interval
-  // LOOK not using bounded
   private int findCoordElementDiscontiguousInterval(double target, boolean bounded) {
     int idx = findSingleHit(target);
-    if (idx >= 0)
-      return idx;
-    if (idx == -1)
-      return -1; // no hits
-
     // multiple hits = choose closest (definition of closest will be based on axis type)
-    return findClosestDiscontiguousInterval(target);
+    if (idx == MULTIPLE_HITS) {
+      return findClosestDiscontiguousInterval(target);
+    }
+    if (bounded && (idx >= axis.getNcoords())) {
+      return -1;
+    }
+    return idx;
   }
 
   boolean intervalContains(double target, int coordIdx) {
@@ -229,22 +231,25 @@ private boolean intervalContains(double target, int coordIdx, boolean ascending)
     return lowerVal <= target && target <= upperVal;
   }
 
-  // return index if only one match, if no matches return -1, if > 1 match return -nhits
+  // return index if only one match
+  // return MULTIPLE_HITS if in several
   private int findSingleHit(double target) {
-    int hits = 0;
+    // edge cases: outside first interval
+    double firstCoord = axis.getCoordEdge1(0);
+    if ((axis.isAscending() && target < firstCoord) || (!axis.isAscending() && target > firstCoord)) {
+      return -1;
+    }
     int idxFound = -1;
     int n = axis.getNcoords();
     for (int i = 0; i < n; i++) {
       if (intervalContains(target, i)) {
-        hits++;
+        if (idxFound >= 0) {
+          return MULTIPLE_HITS;
+        }
         idxFound = i;
       }
     }
-    if (hits == 1)
-      return idxFound;
-    if (hits == 0)
-      return -1;
-    return -hits;
+    return idxFound > -1 ? idxFound : n;
   }
 
   // return index of closest value to target
@@ -273,7 +278,7 @@ private int findClosestDiscontiguousTimeInterval(double target) {
         // must be greater than or equal to the target.
         if (coord >= target) {
           // compute the width (in time) of the interval
-          double width = axis.getCoordEdge2(i) - axis.getCoordEdge1(i);
+          double width = coord - axis.getCoordEdge1(i);
           // we want to identify the interval with the end point closest to our target
           // why? Because a statistic computed over a time window will only have meaning at the end
           // of that interval, so the closer we can get to that the better.
diff --git a/cdm/core/src/main/java/ucar/nc2/ft2/coverage/writer/CFGridCoverageWriter.java b/cdm/core/src/main/java/ucar/nc2/ft2/coverage/writer/CFGridCoverageWriter.java
index 169c784217..1e9063e8ce 100644
--- a/cdm/core/src/main/java/ucar/nc2/ft2/coverage/writer/CFGridCoverageWriter.java
+++ b/cdm/core/src/main/java/ucar/nc2/ft2/coverage/writer/CFGridCoverageWriter.java
@@ -58,6 +58,8 @@ public class CFGridCoverageWriter {
   private static final String BOUNDS = "_bounds";
   private static final String BOUNDS_DIM = "bounds_dim"; // dimension of length 2, can be used by any bounds coordinate
 
+  public static final String TOO_LARGE_MESSAGE = "Request too large";
+
   /** A value class holding information about the write() */
   public static class Result {
     private final long sizeToBeWritten;
@@ -158,7 +160,7 @@ private Result writeFile(CoverageCollection gdsOrg, List<String> gridNames, Subs
       // test if its too large
       long totalSizeOfVars = ncwriter.calcSize();
       if (maxBytes > 0 && totalSizeOfVars > maxBytes) {
-        return Result.create(totalSizeOfVars, false, String.format("Too large, max size = %d", maxBytes));
+        return Result.create(totalSizeOfVars, false, TOO_LARGE_MESSAGE);
       }
 
       writeCoordinateData(subsetDataset, ncwriter);