diff --git a/DCC.cpp b/DCC.cpp
index 248c96a..2725f28 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -514,13 +514,13 @@ void DCC::ackManagerLoop() {
          // detected trailing edge of pulse
           long pulseDuration=micros()-ackPulseStart;
                
-          if (pulseDuration>4000 && pulseDuration<9000) {
+          if (pulseDuration>1000 && pulseDuration<9000) {
             if (debugMode) DIAG(F("\nWACK-OK polls=%d, max=%dmA, pulse=%duS"),ackPollCount, ackMaxCurrent, pulseDuration);
             ackReceived=true;
             DCCWaveform::progTrack.killRemainingRepeats(); // probably no need after 8.5ms!!
             break;  // we have a genuine ACK result
           }      
-           if (debugMode) DIAG(F("\nWACK-bad pulse polls=%d, max=%dmA, pulse=%duS"), ackPollCount, ackMaxCurrent, pulseDuration);
+           if (debugMode) DIAG(F("\nWACK-bad pulse polls=%d, max=%dmA, now=%dmA, pulse=%duS"), ackPollCount, ackMaxCurrent,current, pulseDuration);
           ackPulseStart=0;  // We have detected a too-short or too-long pulse so ignore and wait for next leading edge 
           return; // keep waiting 
          }
diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index f935c66..b8bc54e 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -45,7 +45,7 @@ void DCCEXParser::loop(Stream & stream) {
     } 
     else if (ch == '>') {
       buffer[bufferLength]='\0';
-      parse( stream, buffer);
+      parse( stream, buffer, false); // Parse this allowing async responses
       inCommandPayload = false;
       break;
     } else if(inCommandPayload) {
@@ -109,8 +109,9 @@ void DCCEXParser::setFilter(FILTER_CALLBACK filter) {
 }
    
 // See documentation on DCC class for info on this section
-void DCCEXParser::parse(Print & stream, const byte *com) {
+void DCCEXParser::parse(Print & stream, const byte *com, bool banAsync) {
     DIAG(F("\nPARSING:%s\n"),com);
+    asyncBanned=banAsync;
     (void) EEPROM; // tell compiler not to warn thi is unused
     int p[MAX_PARAMS];  
     byte params=splitValues(p, com); 
@@ -353,7 +354,7 @@ bool DCCEXParser::parseS( Print & stream,int params, int p[]) {
 
  // CALLBACKS must be static 
 bool DCCEXParser::stashCallback(Print & stream,int p[MAX_PARAMS]) {
-       if (stashBusy) return false;
+       if (stashBusy || asyncBanned) return false;
        stashBusy=true; 
       stashStream=stream;
       memcpy(stashP,p,MAX_PARAMS*sizeof(p[0]));
diff --git a/DCCEXParser.h b/DCCEXParser.h
index ed6bfb8..9408de9 100644
--- a/DCCEXParser.h
+++ b/DCCEXParser.h
@@ -8,7 +8,7 @@ struct DCCEXParser
 {
    DCCEXParser();
    void loop(Stream & pstream);
-   void parse(Print & stream, const byte * command);
+   void parse(Print & stream, const byte * command, bool banAsync);
    void flush();
    static void setFilter(FILTER_CALLBACK filter);
    static const int MAX_PARAMS=10;  // Must not exceed this
@@ -18,6 +18,7 @@ struct DCCEXParser
     static const int MAX_BUFFER=50;  // longest command sent in
      byte  bufferLength=0;
      bool  inCommandPayload=false;
+     bool  asyncBanned;   // true when called with stream that must complete before returning
      byte  buffer[MAX_BUFFER+2]; 
     int splitValues( int result[MAX_PARAMS], const byte * command);
      
@@ -28,9 +29,10 @@ struct DCCEXParser
 
     
     static bool stashBusy;
+   
     static Print & stashStream;
     static int stashP[MAX_PARAMS];
-    static bool stashCallback(Print & stream, int p[MAX_PARAMS]);
+    bool stashCallback(Print & stream, int p[MAX_PARAMS]);
     static void callback_W(int result);
     static void callback_B(int result);        
     static void callback_R(int result);
diff --git a/DIAG.h b/DIAG.h
index e5d0213..9fe8fd3 100644
--- a/DIAG.h
+++ b/DIAG.h
@@ -2,8 +2,5 @@
 #define DIAG_h
 
 #include "StringFormatter.h"
-#ifndef DIAG_ENABLED
- #define DIAG_ENABLED true
-#endif
-#define DIAG if (DIAG_ENABLED) StringFormatter::print
+#define DIAG  StringFormatter::print
 #endif
diff --git a/PWMServoDriver.cpp b/PWMServoDriver.cpp
index 8e2edf4..75af8e1 100644
--- a/PWMServoDriver.cpp
+++ b/PWMServoDriver.cpp
@@ -25,7 +25,6 @@
 #include <Arduino.h>
 #include <Wire.h>
 #include "PWMServoDriver.h"
-#define DIAG_ENABLED true
 #include "DIAG.h"