diff --git a/lib/pbio/src/port_lump.c b/lib/pbio/src/port_lump.c
index 49ea35d41..cba71058e 100644
--- a/lib/pbio/src/port_lump.c
+++ b/lib/pbio/src/port_lump.c
@@ -881,8 +881,6 @@ pbio_error_t pbio_port_lump_sync_thread(pbio_os_state_t *state, pbio_port_lump_d
         default_mode = LEGO_DEVICE_MODE_PUP_REL_MOTOR__POS;
     } else if (lump_dev->type_id == LEGO_DEVICE_TYPE_ID_COLOR_DIST_SENSOR) {
         default_mode = LEGO_DEVICE_MODE_PUP_COLOR_DISTANCE_SENSOR__RGB_I;
-    } else if (lump_dev->type_id == LEGO_DEVICE_TYPE_ID_EV3_COLOR_SENSOR) {
-        default_mode = LEGO_DEVICE_MODE_EV3_COLOR_SENSOR__AMBIENT;
     }
     if (default_mode) {
         pbio_port_lump_request_mode(lump_dev, default_mode);
@@ -917,7 +915,9 @@ pbio_error_t pbio_port_lump_data_send_thread(pbio_os_state_t *state, pbio_port_l
 
     PBIO_OS_ASYNC_BEGIN(state);
 
-    pbio_os_timer_set(timer, EV3_UART_DATA_KEEP_ALIVE_TIMEOUT);
+    // Some devices need the NACK keep-alive signal before doing anything, so
+    // initially set the timer to expire soon.
+    pbio_os_timer_set(timer, 1);
 
     for (;;) {
 
@@ -925,8 +925,9 @@ pbio_error_t pbio_port_lump_data_send_thread(pbio_os_state_t *state, pbio_port_l
 
         // Handle keep alive timeout
         if (pbio_os_timer_is_expired(timer)) {
-            // make sure we are receiving data
-            if (!lump_dev->data_rec) {
+            // Make sure we are receiving data. The first time around, we allow
+            // not having any data yet.
+            if (!lump_dev->data_rec && timer->duration == EV3_UART_DATA_KEEP_ALIVE_TIMEOUT) {
                 debug_pr("No data since last keepalive\n");
                 lump_dev->status = PBDRV_LEGODEV_LUMP_STATUS_ERR;
                 return PBIO_ERROR_TIMEDOUT;
@@ -1011,7 +1012,7 @@ pbio_error_t pbio_port_lump_data_recv_thread(pbio_os_state_t *state, pbio_port_l
 
         lump_dev->rx_msg_size = ev3_uart_get_msg_size(lump_dev->rx_msg[0]);
         if (lump_dev->rx_msg_size < 3 || lump_dev->rx_msg_size > EV3_UART_MAX_MESSAGE_SIZE) {
-            debug_pr("Bad data message size %d\n", lump_dev->rx_msg_size);
+            debug_pr("Bad data message size\n");
             continue;
         }