Idle speed control solenoid

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10-31-2005, 02:48 PM

jzlvr1

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Idle speed control solenoid

My 98 B4000 4.0 has been idling high. I found a procedure on 4.0PERFORMANCE.com for "Idle Re-learn". Step 2 say's to disconnect the "Idle Speed Control solenoid". Is the Idle speed control solenoid the same as the “Idle Air Control solenoid”? I disconnected the IAC, and my truck was difficult to start, and would not stay running once it did start. My Haynes manual does not say were the ISC is located. Any ideas?

Thanks.

Daryl Rose

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10-31-2005, 05:01 PM

RangerPilot

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What's high? If the engine is cold, especially if you live in the north, a high idle is perfectly normal.

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10-31-2005, 05:02 PM

Rockledge

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The idle re-learn procedure you reference is not applicable to OBD-II vehicles. Ford in fact instructs NOT to mess with the idle speed stop screw. Here is what the Ford Manual says:

Quote:

Idle Air Trim is designed to adjust the Idle Air Control (IAC) calibration to correct for wear and aging of components. When engine conditions meet the learning requirement, the strategy monitors the engine and determines the values required for ideal idle calibration. The Idle Air Trim values are stored in a table for reference. This table is used by the PCM as a correction factor when controlling idle speed. The table is stored in Keep Alive Random Access Memory (RAM) and retains the learned values even after the engine is shut off. A Diagnostic Trouble Code (DTC) is output to indicate that the Idle Air Trim has reached its learning limits.

Whenever an IAC component is replaced or cleaned or a service affecting idle is performed, it is recommended that Keep Alive RAM be cleared. This is necessary so the idle strategy does not use the previously learned Idle Air Trim values.

To clear Keep Alive RAM, take the cable off the begative battery terminal and wait 10 minutes. It is important to note that erasing DTCs with a scan tool does not reset the Idle Air Trim table.

Once Keep Alive RAM has been reset, the engine must idle for 15 minutes (actual time varies between strategies) to learn new idle air trim values. Idle quality will improve as the strategy adapts. Adaptation occurs in four separate modes. The modes are shown in the following table.

IDLE AIR TRIM LEARNING MODES

NEUTRAL - A/C ON
NEUTRAL - A/C OFF
DRIVE - A/C ON
DRIVE - A/C OFF

In other words, driving and idling in nuetral with the AC on and off is the way to do it.

A high idle can also result from air leaks up and around the throttle body and upper intake area. Check all vacuum hoses and connections, check your PCV and EGR system for leaks, even the intake gaskets could be suspect.

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11-01-2005, 09:04 AM

jimw411

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my truck always idles at around 600-700 rpm with or without the a/c on. If it's cold it idles at 1,000-1,100 rpm and slowly drops down to normal as the truck warms up. If it is hot outside usually 100 degrees plus and i'm in traffic the idle will jump back up to 1,100 rpm so that the fan and water pump spin faster to keep the engine temp down. Also, my truck is a stick an as long as the truck is moving 5-10mph or above it idles at around 1,100 rpm also. Like if i'm going down a grade and put in in neutral and let the clutch out it will sit there at 1,100 rpm. It's been like that since day one.

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