Guys, I need help with my wife's 4.0 Explorer...lately it has been stalling when you have to brake hard at the last minute, or stop on an incline....the rpms just drop off until it stalls. It will throw a code at that point, but then when it restarts, the code disappears, and a scanner will report no codes stored. If you anticipate the stop, and brake gradually, then the transmission has the chance to downshift, and keep the rpms up...

Plugs and filters have all been changed...

Guys in another bulletin board for Rangers and Explorers said it was the IAC on the air intake. But our Explorer is a 2004, and Ford stopped putting IACs on the 4.0 that model year...

Anybody have a suggestion? This is really getting frustrating...

 

Check for vacuum leaks. The pcv tube elbows will collapse. It is located near the front of the engine behind the throttlebody and runs around the intake to the rear of the driver's side valve cover.

 

Thanks for the reply, Bronc...I went through the engine looking for vacuum leaks last The pcv hose was fine...

finally got frustrated enough to take it to the dealership. They ran diagnostics on it, couldn't find any codes (like I said when I dropped it off) and couldn't replicate it (I told them it was intermittent). But they took the time to research the situation, and found a TSB on it where the PCM needed to be reflashed because it wasn't recognizing the throttle position sensor.

All well and good though...I let them flush and fill the tranny while they had it (screwy sealed transmission on this Explorer). When my wife and I pulled out, she was actually accelerating away from me, until my truck kicked down a gear!

 

bigbronc,
You just answered the questions I posted on my thread for a 2002 Ranger with the P0171/P0174 codes. I found the problem with the rubber 90 degree elbow but didn't follow it to the rear of the engine to see what it's function was. You didn't intend to, but you helped me out.
Thanks,
TJK

 

well, guys, it lasted for all of 4 days, and then it started acting up again. I went through every vacuum line, expecting to find some small crack I missed, cleaned the throttle body out (never saw so much carbon buildup in my life), and let it idle again. That morning, I had reset the computer and replaced the ignition coil. Late last night, it finally posted a code...one of the oxygen sensors had gone bad. After all that...this has been going on for at least 4 weeks...maybe longer. I now have the O2 sensors on the way...

Just goes to show...never know what is causing a problem until the flippin' code comes up!