diff --git a/apps/agpsdata/ChangeLog b/apps/agpsdata/ChangeLog
index 89844a132..8ada244d7 100644
--- a/apps/agpsdata/ChangeLog
+++ b/apps/agpsdata/ChangeLog
@@ -2,3 +2,4 @@
 0.02: Load AGPS data on app start and automatically in background
 0.03: Do not load AGPS data on boot
       Increase minimum interval to 6 hours
+0.04: Write AGPS data chunks with delay to improve reliability
diff --git a/apps/agpsdata/app.js b/apps/agpsdata/app.js
index 647723bb4..4a6d2ba5c 100644
--- a/apps/agpsdata/app.js
+++ b/apps/agpsdata/app.js
@@ -36,7 +36,7 @@ function updateAgps() {
   g.clear();
   if (!waiting) {
     waiting = true;
-    display("Updating A-GPS...");
+    display("Updating A-GPS...", "takes ~ 10 seconds");
     require("agpsdata").pull(function() {
       waiting = false;
       display("A-GPS updated.", "touch to close");
diff --git a/apps/agpsdata/lib.js b/apps/agpsdata/lib.js
index 7d9758c0a..34608a5c6 100644
--- a/apps/agpsdata/lib.js
+++ b/apps/agpsdata/lib.js
@@ -8,41 +8,52 @@ var FILE = "agpsdata.settings.json";
 var settings;
 readSettings();
 
-function setAGPS(data) {
-  var js = jsFromBase64(data);
-  try {
-    eval(js);
-    return true;
-  }
-  catch(e) {
-    console.log("error:", e);
-  }
-  return false;
+function setAGPS(b64) {
+  return new Promise(function(resolve, reject) {
+    var initCommands = "Bangle.setGPSPower(1);\n"; // turn GPS on
+    const gnsstype = settings.gnsstype || 1;       // default GPS
+    initCommands += `Serial1.println("${CASIC_CHECKSUM("$PCAS04," + gnsstype)}")\n`; // set GNSS mode
+    // What about:
+    // NAV-TIMEUTC (0x01 0x10)
+    // NAV-PV (0x01 0x03)
+    // or AGPS.zip uses AID-INI (0x0B 0x01)
+
+    eval(initCommands);
+
+    try {
+      writeChunks(atob(b64), resolve);
+    } catch (e) {
+      console.log("error:", e);
+      reject();
+    }
+  });
 }
 
-function jsFromBase64(b64) {
-  var bin = atob(b64);
-  var chunkSize = 128;
-  var js = "Bangle.setGPSPower(1);\n"; // turn GPS on
-  var gnsstype = settings.gnsstype || 1; // default GPS
-  js += `Serial1.println("${CASIC_CHECKSUM("$PCAS04,"+gnsstype)}")\n`; // set GNSS mode
-  // What about:
-  // NAV-TIMEUTC (0x01 0x10)
-  // NAV-PV (0x01 0x03)
-  // or AGPS.zip uses AID-INI (0x0B 0x01)
+var chunkI = 0;
+function writeChunks(bin, resolve) {
+  return new Promise(function(resolve2) {
+    const chunkSize = 128;
+    setTimeout(function() {
+      if (chunkI < bin.length) {
+        var chunk = bin.substr(chunkI, chunkSize);
+        js = `Serial1.write(atob("${btoa(chunk)}"))\n`;
+        eval(js);
 
-  for (var i=0;i<bin.length;i+=chunkSize) {
-    var chunk = bin.substr(i,chunkSize);
-    js += `Serial1.write(atob("${btoa(chunk)}"))\n`;
-  }
-  return js;
+        chunkI += chunkSize;
+        writeChunks(bin, resolve);
+      } else {
+        if (resolve)
+          resolve(); // call outer resolve
+      }
+    }, 200);
+  });
 }
 
 function CASIC_CHECKSUM(cmd) {
   var cs = 0;
-  for (var i=1;i<cmd.length;i++)
+  for (var i = 1; i < cmd.length; i++)
     cs = cs ^ cmd.charCodeAt(i);
-  return cmd+"*"+cs.toString(16).toUpperCase().padStart(2, '0');
+  return cmd + "*" + cs.toString(16).toUpperCase().padStart(2, '0');
 }
 
 function updateLastUpdate() {
@@ -53,23 +64,30 @@ function updateLastUpdate() {
 }
 
 exports.pull = function(successCallback, failureCallback) {
-  let uri = "https://www.espruino.com/agps/casic.base64";
-  if (Bangle.http){
-    Bangle.http(uri, {timeout:10000}).then(event => {
-      let result = setAGPS(event.resp);
-      if (result) {
-          updateLastUpdate();
-          if (successCallback) successCallback();
-      } else {
-          console.log("error applying AGPS data");
-          if (failureCallback) failureCallback("Error applying AGPS data");
-      }
-    }).catch((e)=>{
-      console.log("error", e);
-      if (failureCallback) failureCallback(e);
-    });
+  const uri = "https://www.espruino.com/agps/casic.base64";
+  if (Bangle.http) {
+    Bangle.http(uri, {timeout : 10000})
+        .then(event => {
+          setAGPS(event.resp)
+              .then(r => {
+                updateLastUpdate();
+                if (successCallback)
+                  successCallback();
+              })
+              .catch((e) => {
+                console.log("error", e);
+                if (failureCallback)
+                  failureCallback(e);
+              });
+        })
+        .catch((e) => {
+          console.log("error", e);
+          if (failureCallback)
+            failureCallback(e);
+        });
   } else {
     console.log("error: No http method found");
-    if (failureCallback) failureCallback(/*LANG*/"No http method");
+    if (failureCallback)
+      failureCallback(/*LANG*/ "No http method");
   }
 };
diff --git a/apps/agpsdata/metadata.json b/apps/agpsdata/metadata.json
index 1ce299532..203a00f72 100644
--- a/apps/agpsdata/metadata.json
+++ b/apps/agpsdata/metadata.json
@@ -2,7 +2,7 @@
   "name": "A-GPS Data Downloader App",
   "shortName":"A-GPS Data",
   "icon": "agpsdata.png",
-  "version":"0.03",
+  "version":"0.04",
   "description": "Once installed, this app allows you to download assisted GPS (A-GPS) data directly to your Bangle.js **via Gadgetbridge on an Android phone** when you run the app. If you just want to upload the latest AGPS data from this app loader, please use the `Assisted GPS Update (AGPS)` app.",
   "tags": "boot,tool,assisted,gps,agps,http",
   "allow_emulator":true,