2005 Mustang engine fail safe mode! HELP

eyeeatrice said:

My 2005 keeps going into engine failsafe mode but when i turn it off it will be back to normal and then eventually goes back into failsafe mode after driving for about 20 30 minutes. I loaded my tune again just to be sure. My last dyno eveything looked perfect A/F was right on point. Anyone know what to do or have had this problem before

Click to expand...

Check you CAI where it meet the TB for leaks ,especially underside. Make sure you have a good connection on the Maf sensor.Check all pcv hoses to be tight. Check your oil also. Did you put the tune back to stock then load the custom tune?

It could be a dirty throttle body or bad TPS.

Thereaper said:

It could be a dirty throttle body or bad TPS.

Click to expand...

Yes, definitely check to see if the throttle body is dirty.

ok so i reconnected the zex wire to the wire on the TPS just to be sure it wasnt a bad connection. Drove to work this morn about 40 minutes and no problems. If it happens again i'm gonna clean the TB and if it persists i will dyno again to see how my tune is.

Failsafe mode

Failsafe mode is activated when TPS input does not equal what the ECU is expecting from the pedal position sensor and the command from the throttle actuator motor. Excessive engine temp will trigger it also but is not likely in your situation.
With that said the most likely cause is the WOT switch connection. TPS voltage is low and the current is very low (milliamps) so a perfect connection is very important. The best way is to solder the connection and shrink tube it. Splice clips are junk in this application and crimp style butt splices are not much better.