Contour Enthusiasts Group Archives Forums General Troubleshooting engine rough when a/c running

hi i am a new member, i want to say hi to all this is a great site. i also have a question. i just purchased a 2000 contour svt with 65,000 miles, i don't know much about the history of the car other than the carfax report that had no major issues to worry about. i drove it from florida to michigan this week and the car runs great, but when the a/c or the defroster is on it runs rough. it feels like it stall when i let of the gas. or when i am driving it will feel almost like a jerking feeling or even like it stall for a second. hard to explain. let me know if i can add any more info to help diagnose the problem. thanks

Welcome . Clean/change the IAC 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.

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).

thanks i will try that and post the results.

Also the throttle hang fix tends to reduce this.

It is inherent in the SVT. To me it feels like the idle air control is working against the idle. The speculation is that the SVT is more prone to this because of the hotter cams (slightly less low end torque) as well as a lighter flywheel.

On my car it is most pronounced when running the A/C and trying to hold a steady speed in 5th gear at about 35 to 40 mph.

Having the engine in good tune (plugs and wires in good condition), the throttle body clean, the IAC clean, and the injectors clean seem to help some, and then the throttle hang fix seems to remove even more of it.