Contour Enthusiasts Group Archives Forums General Troubleshooting Stalling problem

'95 Mystique, Duratec V6.

Problem I am now having is that when I start up in the morning, the car would rev around 1200 rpm for a minute and then it would go down to 600-700 rpm (normal for the car). However after a few seconds of being at the lower rpm, it would start surging between 600 and 200 rpm and stall. It will start up right away no problem, but would go into the stalling routine again until fully warmed up.

When I try to back up out of the driveway before warmed up, it would surge and I would have to keep one foot on the brake while I play with the gas pedal to keep it from stalling.

Sometimes when I go out somewhere (like shopping) and I only leave the car for about 20 minutes or so, it will still do that stalling routine. Once I am moving it doesn't do it.

Also, when I accelerate from a standing start, the car vibrates like it's missing a cylinder until I reach cruising speeds. Only happens during acceleration. Lots of power in the car still, but while cruising I can still feel it seems to miss now and then.

These two problems both started at the same time. Any ideas?

TIA!

Any CEL codes? If none, clean/check/change the IAC valve and clean the MAF sensor.

Idle Air Control Valve.
IAC cleaning
from Ray's UIM/LIM how to in Duratec Maintenance how to.

"Replacing the IAC gasket:
(From IAC faq)
Over time, the IAC (Idle Air Control) valve becomes sticky due to buildup from the EGR and PCV systems. It can stick partially open such that idle quality is adversely affected, and engine RPM's will not drop below 1500. For a while, blipping the throttle will restore normal idle, but this only works for so long.

The fix is to remove the IAC valve by unbolting the two 8mm bolts that hold it on and disconnected the wiring plug. If you are careful enough, replacement of the gasket will not be necessary. The gasket costs less than US $1.00, so it is no tragedy if you destroy it. Once the valve is off, spray it out with some carb/intake cleaner and make sure any gunky residue is gone. Reattach, and you are done. It is a lot cheaper than a new IAC, which runs around US $70. Note: Ford claims the IAC cannot be cleaned, but this is not true in my experience." Ray.

http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=v6maint&Number=931756&Forum=v6maint&Words=UIM%20aide&Match=And&Searchpage=1&Limit=25&Old=allposts&Main=931756&Search=true#Post931756

Idle Air Control (IAC) Valve


Removal

1. Disconnect battery ground cable

2. Remove the air cleaner outlet tube and resonator assembly.
3. Disconnect the main chassis vacuum line.

4. Disconnect the ignition coil and radio interference capacitor wiring.

5. Remove the fuel line bracket retaining bolt.

6. On 2.0L engine equipped vehicles, raise vehicle on hoist.
7.
7. Disconnect the engine control sensor wiring or fuel charging wiring (depending upon application) from the idle air control valve (IAC valve) at the idle air control valve connector.

8. On 2.5L engine equipped vehicles, remove retainer for engine control sensor wiring from the upper retaining stud bolt.

9. Remove the two idle air control valve retaining bolts or stud bolt (depending upon application).

10. Remove the idle air control valve and idle air control valve gasket.

Installation

1. Note: If scraping is necessary, be careful not to damage idle air control valve or intake manifold idle air control valve gasket surfaces or drop material into intake manifold.

Clean idle air control valve gasket mating surfaces.

2. To install idle air control valve, reverse Removal procedure. Tighten the fuel line bracket bolt to 8-12 N-m (71-106 lb-in).

3. On 2.5L engine equipped vehicles, tighten the retaining bolt and stud bolt to 8-12

4. On 2.0L engine equipped vehicles, tighten the idle air control valve retaining bolts to 8-11 N-m (71-97 lb-in).

MAF sensor
http://www.contour.org/mods/mods.php?s=howto&displayid=36
and
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=zetecmaint&Number=989728&page=&view=&sb=5&o=&fpart=1&vc=1
and
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/cb/25/0900823d801bcb25.jsp

Well on the way home from work, the car started bucking, snarling and spitting like it suddenly developed rabies and then the CEL came on. I gunned the gas for a sec and the light went out but it ran very very rough. I just made it home.

After shutting it down and letting it cool off, I started taking the air cleaner housing apart so I could clean the MAF and that'[s when I saw this 1" "S" shaped hose running from a round valve at the back of the engine to this black round thing that was connected to the breather tube behund the MAF. I saw there was a large tear on the "S" shaped hose right at the valve, so I grabbed a piece of heater hose I had left over from replacing my heater hoses and cut it to size and put it on.

Started the car and good grief, dang thing ran so smoothly my next door neighbour who came over to see what I was up to didn't know the engine was running. Took the car out for a test drive and it ran smooth as silk. STill a slight vibration when accelerating but I suspect I have a CV joint issue or something. Will have the mechanic check that out.

Just happy to have my daily driver back without any major expense.