1997 Ford Thunderbird

WOLFDOG62

MEMBER
1997 FORD THUNDERBIRD
V8
2WD
AUTOMATIC
160,000 MILES

We were told to change the fuel filter, if it gets to hot or to cold it could keep it from starting so we did. Added Heet to the gas. Still when you start it as long as you keep your foot on gas it will run. Will not go to idle by itself. As soon as I changed the fuel filter it was ok for a week. I drove my wife to work and by the time I got to the parts house it was ok. That was when I changed the fuel filter. Now it is right back to not idleing. What do I try next? I didn't see the donate box. Lets see how this works first

Friday, December 19th, 2008 AT 4:53 PM

1 Reply

DAVE H

MECHANIC
13,384 POSTS

Check/clean or replace IAC

IDLE SPEED
NOTE:Idle Air Control (IAC) valve is also known as By-Pass Air (BPA) valve.

Idle Air Control (IAC) Valve Assembly
IAC valve assembly is used to control idle speed and provide a dashpot function. IAC valve assembly meters inlet air around the throttle plate through a by-pass within the IAC valve assembly and throttle body. See Fig. 6 or Fig. 7 .
The PCM determines desired idle speed or air by-pass and signals the IAC valve assembly through specified duty cycle. The IAC solenoid is built into IAC valve assembly. IAC solenoid responds by positioning the IAC valve to control amount of air by-passed. PCM monitors engine speed and adjusts IAC duty cycle to achieve desired RPM.
Fig. 6: Cross-Sectional View Of IAC Valve Assembly Components (Hitachi)
Courtesy of FORD MOTOR CO.
Fig. 7: Cross-Sectional View Of IAC Valve Assembly Components (Nippondenso)
Courtesy of FORD MOTOR CO.