Intermittent limp mode

[thunderman0703]

I have an 05 explorer xlt with the 4.0 v6. Occasionally directly when starting it immediately goes into limp mode (wrench light comes on/failsafe mode) and if you shut it off and then turn it back on then it's gone. Another possibly related occurrence is whenever you're driving and lightly accelerate enough to where it acts like it wants to downshift to get a little oomph it shudders just a little. I am going to pull codes again today as i suspect the tps. I was wondering if anyone encountered these symptoms on a pretty much regular basis and if they solved them. Also there is a vacuum sound and a thump shortly after startup around the gas/brake pedal area which i assume is a heat or air door setting itself up for the ride. And while I'm on a role the cruise control occasionally won't turn on if I tap the brakes until I hit them a few times as if that switch was going out. Any help or redirection towards a solution to any of these problems would be greatly appreciated. TIA

 

[p38fln]

There are two disconnects for Ford cruise control modules, one is the brake light switch. Make sure your brake lights are actually working!

The other disconnect is a brake pressure switch which activates at 125 PSI of brake line pressure, this disconnect removes power from the cruise control instead of just deactivating it. This is to prevent accidents caused by sticking cruise controls.

You probably have a minor vacuum leak losing pressure when the engine is off, which is causing the noise you are hearing.

Shuddering when you start giving it gas is a sign of a misfire, which on a 2005 probably indicates you need to replace the spark plugs & wires right now.

 

[thunderman0703]

Update: my mechanic at my warehouse pulled my codes for me and came up with these P0401 P2106, and P2135. He told me to turn the ignition forward without starting and prop open the throttle body and clean it. I turned it forward and propped the gas pedal down and cleaned it that way. It's running a heck of a lot better and since then (2 weeks) the limp mode only happened once. My next step will be the plugs and wires. Maybe after the UGA game today! Thank you p38fln

 

[05_moutianeer_mn]

My truck went into fail safe mode when the alternator voltage regulator went bad and put 16.4v into the battery most accessories shut down but truck still ran I replaced the alternator.