Engine idle speed
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Junior Member
Joined: Nov 1999
Posts: 7
Likes: 0
From: Houston, TX
Engine idle speed
I had my 5.4L engine replaced about 9,000 miles ago and everything seems OK, except the new engine idle speed with the air conditioning operating needs increasing about 100 RPM. Now that it is warm here in Texas and I use my air conditioning the engine has a harmonic vibration that is annoying during idle at a stop light etc. When I use the accelerator and speed up the engine to 750 RPM from 650 it is OK. I reset the computer and it increased the speed about 50 RPM, but it needs a little more. Is the engine idle speed controlled only by the computer or can it be adjusted?
Senior Member
Joined: Aug 1999
Posts: 1,565
Likes: 1
From: Columbus, Georgia
The computer controls the idle speed and you are not able to manually adjust it.
This is how it works according to Chiltons, "The idle air control (IAC) valve adjusts the engine idle speed. The valve is located on the right side of the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain proper idle speed."
* DO NOT attempt to clean the IAC valve.
"Cleaners will damage the internal components of the IAC. If resistance is not between 6-13 ohms..the valve may be faulty."
Hope this helps!
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2000 F-150 XLT, 4x2, 5.4L Supercab, Styleside, Black with silver two-tone, 3.55, class III towing package with heavy duty cooling package, 4 wheel disk ABS, overhead console, sliding rear window, keyless entry, dark graphite interior, in dash CD, Pendaliner bedliner, K&N air filter, rubberized undercoating, cabin filtration system, Bugflector II, 5W-30 Mobil 1, engine build 10/4/99, Superchip now installed..WOW!!!!
[This message has been edited by Dustoff (edited 03-10-2000).]
This is how it works according to Chiltons, "The idle air control (IAC) valve adjusts the engine idle speed. The valve is located on the right side of the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain proper idle speed."
* DO NOT attempt to clean the IAC valve.
"Cleaners will damage the internal components of the IAC. If resistance is not between 6-13 ohms..the valve may be faulty."
Hope this helps!
------------------
2000 F-150 XLT, 4x2, 5.4L Supercab, Styleside, Black with silver two-tone, 3.55, class III towing package with heavy duty cooling package, 4 wheel disk ABS, overhead console, sliding rear window, keyless entry, dark graphite interior, in dash CD, Pendaliner bedliner, K&N air filter, rubberized undercoating, cabin filtration system, Bugflector II, 5W-30 Mobil 1, engine build 10/4/99, Superchip now installed..WOW!!!!
[This message has been edited by Dustoff (edited 03-10-2000).]