diff --git a/gtsam/navigation/ScenarioRunner.h b/gtsam/navigation/ScenarioRunner.h
index 67b9d0b0c..9cd5c0d41 100644
--- a/gtsam/navigation/ScenarioRunner.h
+++ b/gtsam/navigation/ScenarioRunner.h
@@ -24,7 +24,7 @@
 
 namespace gtsam {
 
-static double intNoiseVar = 0.0001;
+static double intNoiseVar = 0.0000001;
 static const Matrix3 kIntegrationErrorCovariance = intNoiseVar * I_3x3;
 
 /// Simple class to test navigation scenarios
@@ -33,16 +33,16 @@ class ScenarioRunner {
   ScenarioRunner(const Scenario& scenario) : scenario_(scenario) {}
 
   /// Integrate measurements for T seconds into a PIM
-  ImuFactor::PreintegratedMeasurements integrate(
-      double T, boost::optional<Sampler&> gyroSampler = boost::none,
-      boost::optional<Sampler&> accSampler = boost::none) {
+  ImuFactor::PreintegratedMeasurements integrate(double T,
+                                                 Sampler* gyroSampler = 0,
+                                                 Sampler* accSampler = 0) {
     // TODO(frank): allow non-zero
     const imuBias::ConstantBias zeroBias;
-    const bool use2ndOrderCoriolis = true;
+    const bool use2ndOrderIntegration = true;
 
     ImuFactor::PreintegratedMeasurements pim(
         zeroBias, scenario_.accCovariance(), scenario_.gyroCovariance(),
-        kIntegrationErrorCovariance, use2ndOrderCoriolis);
+        kIntegrationErrorCovariance, use2ndOrderIntegration);
 
     const double dt = scenario_.imuSampleTime();
     const double sqrt_dt = std::sqrt(dt);
@@ -86,14 +86,14 @@ class ScenarioRunner {
     Pose3 prediction = predict(integrate(T)).pose;
 
     // Create two samplers for acceleration and omega noise
-    Sampler gyroSampler(scenario_.gyroNoiseModel(), 29285);
+    Sampler gyroSampler(scenario_.gyroNoiseModel(), 10);
     Sampler accSampler(scenario_.accNoiseModel(), 29284);
 
     // Sample !
     Matrix samples(9, N);
     Vector6 sum = Vector6::Zero();
     for (size_t i = 0; i < N; i++) {
-      Pose3 sampled = predict(integrate(T, gyroSampler, accSampler)).pose;
+      Pose3 sampled = predict(integrate(T, &gyroSampler, &accSampler)).pose;
       Vector6 xi = sampled.localCoordinates(prediction);
       samples.col(i) = xi;
       sum += xi;
@@ -106,10 +106,10 @@ class ScenarioRunner {
     for (size_t i = 0; i < N; i++) {
       Vector6 xi = samples.col(i);
       xi -= sampleMean;
-      Q += xi * (xi.transpose() / (N - 1));
+      Q += xi * xi.transpose();
     }
 
-    return Q;
+    return Q / (N - 1);
   }
 
  private:
diff --git a/gtsam/navigation/tests/testScenarioRunner.cpp b/gtsam/navigation/tests/testScenarioRunner.cpp
index c38b9a20a..517e488dd 100644
--- a/gtsam/navigation/tests/testScenarioRunner.cpp
+++ b/gtsam/navigation/tests/testScenarioRunner.cpp
@@ -27,10 +27,11 @@ static const double degree = M_PI / 180.0;
 /* ************************************************************************* */
 TEST(ScenarioRunner, Forward) {
   const double v = 2;  // m/s
-  Scenario forward(Vector3::Zero(), Vector3(v, 0, 0), 1e-2, 0.1, 0.00001);
+  Scenario forward(Vector3::Zero(), Vector3(v, 0, 0), 1e-2, 0.000001, 1);
 
   ScenarioRunner runner(forward);
   const double T = 1;  // seconds
+
   ImuFactor::PreintegratedMeasurements pim = runner.integrate(T);
   EXPECT(assert_equal(forward.pose(T), runner.predict(pim).pose, 1e-9));
 
@@ -41,8 +42,8 @@ TEST(ScenarioRunner, Forward) {
 /* ************************************************************************* */
 TEST(ScenarioRunner, Circle) {
   // Forward velocity 2m/s, angular velocity 6 degree/sec
-  const double v = 2, omega = 6 * degree;
-  Scenario circle(Vector3(0, 0, omega), Vector3(v, 0, 0));
+  const double v = 2, w = 6 * degree;
+  Scenario circle(Vector3(0, 0, w), Vector3(v, 0, 0));
 
   ScenarioRunner runner(circle);
   const double T = 15;  // seconds
@@ -60,6 +61,7 @@ TEST(ScenarioRunner, Loop) {
 
   ScenarioRunner runner(loop);
   const double T = 30;  // seconds
+
   ImuFactor::PreintegratedMeasurements pim = runner.integrate(T);
   EXPECT(assert_equal(loop.pose(T), runner.predict(pim).pose, 0.1));
 }