Taurus Car Club of America : Ford Taurus Forum - View Single Post - Sable '04 DOHC unable to accelerate, runs rough, stumbles
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post #1 of (permalink) Old 06-20-2014, 02:24 PM Thread Starter
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Sable '04 DOHC unable to accelerate, runs rough, stumbles

Mercury Sable, 2004, 24 Valve, DOHC, 110K miles.

Recent to event, things done: Oil change, new spark plugs, checked ignition coils, cleaned injectors, new fuel filter, new PCV valve and good PCV-elbow tube, cleaned EGR valve - needle moves with vacuum applied and port is not plugged, cleaned TB, IAC and MAF.

Prior performance: car was running okay but often does not respond sharply to acceleration. It performed within 18 - 22 mpg. About two weeks before event, car would not start at first crank when cold, but after it warms up or during the day, it usually starts at first crank - battery determined not the reason. Also, some rattling sound from the heatshield/exhaust area by the engine wall.

The event:
While driving car suddenly began to dramatically lose power and would not accelerate as I give it more gas. Within about 3 minutes, it would not go beyond 10 - 20 mph, jerks and stumbles as if trying to accelerate but unable to, runs rough, and NO check engine light. To go up a slight incline on the road was like crawling at snail speed. While in Park or Neutral, it idles somewhat more stable than in Drive, but still runs rough and the rpm flunctuates around 800rpm. Checked for OBD2 codes and pulled P0442 as yellow.

After event, the following services were done but not exactly in order:
Checked spark plugs-ok, PVC valve and tube-ok, EGR valve and port-ok, cleaned MAF, checked TB and IAC-ok, replaced TPS, swapped out the EGR regulator solenoid and the fuel pressure regulator with used ones, the checked for vauum leaks-none found, rattling heatshield removed (was held in place by plastic). After these services, the problem still remains - rough idle, stumbling on acceleration and not able to rev up (and hold) above about 2500rpm before it stumbles down in rpm to as low as 200rpm sometime and may even cutoff. Still no CEL code. Car now starts usually at first crank, revs to about 1500rpm for about 20 - 50 secs, then goes down to about 800 rpm and flunctuates. Still rattling sound from the exhaust area.

Please your advice will be appreciated.
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