2003 Mountaineer(Explorer) Stalls while on highway

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chuckles1856

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Greeings All,

Well I'm usually in the FSB forum but now I've got an issue with the Merc Mountaineer.

Was driving in the mountains on the Intersate yesterday and the engine decided it was just going to stall out.

Pulled over, waited a minute and restarted with no issues.

Started driving again and within 15 minutes it did it again.

At that point I just took it back home.  Tried to pull code but there are none?!?!

I've been driving it ever since and no issues.  City and highway both.

Altitude?  Bad gas? Fuel pump? 

Thoughts?  I'm stumped and the wife is now paranoid.  :)

 

miesk5

96 Bronco 5.0
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yo C,

I have tried to reply twice so far, but Comcast decided to shut the cable down; so,

I will make last attempt for today now;

Re your, "Tried to pull code but there are none?!?!"
Did the Scan Tool Report go through the dignostics & report back w/a Pass Code?
 
or
It didn't go through diagnostics or would not power up?
If so, ck Cig. Lighter Fuse; a common issue bec OBD II Port shares fuse  w/Cig Lighter and this goes back to my 96 Bronco where fuse blew due to short under dash due to chaffing of power wire from fuse to OBD II Port and Lighter
 
Here is one possibilty;
 
IDLE AIR CONTROL (IAC) VALVE DIAGNOSTIC SERVICE TIPS  03-3-5
http://content.chiltonsonline.com/TSB/displayTSBHandler.ashx?assetID=34632&key=6kAUBD5BruOJf%2f3tgozUqjXM3RdbjcQqW4sVWiE%2fp2IojfpfKqM07dr61%2bQAWHtTlUyAMdqtvD3BAzQX3LzzZ1HtvaqQCWbcFrUJG7DG7It3wuYQDQZ1Vv5tIb%2fKG%2bRvp%2fOqBX%2fYFE6xcQeF1vK2vA%3d%3d
 
 
EXCERPTS:
 
2000-2003 SABLE, MOUNTAINEER & Others
Some vehicles may exhibit drivability conditions.

These may include:
No start
Difficult to start
Stall
Low idle
Rough idle
High idle
Hesitation/surge while accelerating or at steady speed

These conditions may be intermittent with no Diagnostic Trouble Codes (DTC) and no Malfunction Indicator lamp (MIL). In some cases, DTC and MIL may be evident.

ACTION

Trouble cannot be identified with 95% of returned Idle Air Control (IAC) valves. The following procedure is supplemental information to normal diagnostics to facilitate accurate information of malfunctioning valves. These symptoms would include engine stall, hard start, crank/no start, idling problems, and Idle Speed Control System related DTCs.
Perform normal diagnostics.

IF THE ENGINE STALLED WHILE THE VEHICLE WAS IN GEAR AND MOVING THE POSSIBILITY OF THE IAC VALVE CAUSING THIS IS UNLIKELY UNLESS IT OCCURRED ON DECELERATION.
IAC valves can be damaged from engine induction backfires. Many times the customer may not notice the induction backfire but will notice the high idle afterwards. Indications of valve damage can be a shiny, almost polished appearance in: the interior of the valve and a dislocated pintle.

An IAC valve damaged by backfire should be replaced. Refer to Figure 1.

Never clean an IAC valve.

Inspect PCV system for leaks especially looking for cracks along any rubber elbow joints; also verify that the correct PCV valve is installed.

 Inspect for vacuum hoses loose or disconnected from intended ports and connections. Induction backfire can loosen or disconnect vacuum hoses.

Two indicators can help you identify if a vacuum leak is present, even if the engine RPM appear normal in the service bay. If the duty cycle is below specification that is indicative that the engine is receiving too much air (from a vacuum leak) and the PCM is ordering the valve to close up to restrict flow. Another indication is fuel trim PIDS (LONGFT1, LONGFT2, SHORTFT1, etc.), if short term fuel trims are high (above specification) this is a possible indication of a vacuum leak, making the engine run lean, and the PCM is attempting to compensate.
Miesk5 Note; some Scan Tools can read PIDs
Verify PCM harness integrity by performing a. wiggle test on the harness (as well as IAC connector & wiring) while the engine is running and observe the IAC duty cycle and engine performance. Should abnormalities be observed, repair the harness as required.
 
If no DTC’s present check the following items in this order before examining the IAC valve:

BARO Hz reading - Refer to Barometric Pressure Chart listed in this TSB

• Battery and fuse box power leads & Fusible Links

• Ground wire attachments

IAC valves can be damaged from engine

Wiring (wiggle test)

• PCM voltage

Vacuum leaks
.

Idle Air Control Valve Testing

03 Mountaneer IAC Testing Diagram.gif

Miesk5 Note; VPWR is Vehicle Power supply voltage (regulated 10-14 volts)
 

  1. Turn the ignition switch to the OFF position.
  2. Disengage the wiring harness connector from the IAC valve .
  3. Using an ohmmeter, measure the resistance between the terminals of the valve.
  4. Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR terminal and the negative lead on the ISC terminal.
  5. If the resistance is not 7-13 ohms, replace the IAC valve


I will post more if I can find more Ford info.

EDIT;

Here are some Component Location Diagrams;

IAC (shows Connector C1066), TPS, EGR DPEFE

http://content.chiltonsonline.com/content/images/WD/Ford/139/WD_Ford_139962.pdf

Connector C1066 Pin-Out Diagram that does confirm above Test Connector Diagram;

http://content.chiltonsonline.com/content/images/WD/Ford/140/WD_Ford_140026.pdf

MAFSensor

http://content.chiltonsonline.com/content/images/WD/Ford/139/WD_Ford_139901.pdf

Crankshaft Position Sensor;

http://content.chiltonsonline.com/content/images/WD/Ford/139/WD_Ford_139895.pdf

 
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