Idle Issue

Tiny
MOPAR4LIFE98
  • MEMBER
  • 1998 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 186,000 MILES
P1294 code came up, I have noticed since I Did a Tune up Plugs, wires, cap, Rotor, my idle wants to hang at about 1k and some times fluctuates. I have always had a problem with No.8 cylinder getting oil on the plug and fouling it out so I put a Spark fouler on it. I have also had prior problems with the TPS, witch from what I understand they had a lot of problems with that year. My question being what should I check or what could be causing the idle problem I have checked all vacuum, one theory I have is the crack in my throttle Body but prior to the tune up I didn't have an idle problem. Any advice would be great!
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Thursday, February 17th, 2011 AT 10:54 PM

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Tiny
BMRFIXIT
  • EXPERT
TEST TC-138A: TARGET IDLE NOT REACHED

On all bodies, except AB body, go to step 3). On AB body, use scan tool to read DTCs. If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed count is "0", go to step 3). If DTC SPECIFIC GOOD TRIPS counter is not displayed or displayed count is not "0", go to next step.
Using scan tool, read and record FREEZE FRAME data. Attempt to duplicate conditions in FREEZE FRAME data. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS counter changes to "0", go to next step. If DTC SPECIFIC GOOD TRIPS counter does not change to "0", conditions required to set DTC are not present at this time. Operate vehicle for one DTC specific good trip. Erase DTC and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES.
Turn engine off, ignition on. With throttle linkage at idle position and throttle plate fully closed against its stop, check throttle plate and linkage for binding. Repair throttle plate and linkage as necessary and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies. If throttle linkage and plate are okay, go to next step.
On AB body, go to step 6). On all other bodies, start engine. Allow engine to idle for 60 seconds. If vehicle is equipped with automatic transmission, set parking brake, depress brake pedal and put gear selector in Drive. Go to next step.
On all vehicles, use scan tool to read TARGET IDLE and engine speed (RPM). If engine RPM is within -100 or +200 RPM of target idle, go to step 8). If engine RPM is not within specification, go to next step.
NOTE:The following test step is invalid if engine has any vacuum leaks.

Check engine, brake booster and vacuum hoses for leaks. Ensure PCV valve is operating properly. Repair vacuum leaks or replace PCV valve as necessary and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on all other bodies. If no vacuum leaks exist and PCV valve is operating properly, go to next step.
Using scan tool, actuate IAC wiggle test. Idle Air Control (IAC) motor should raise and lower idle speed with scan tool display. If IAC motor does not operate as specified, perform TEST TC-25A: IDLE AIR CONTROL MOTOR CIRCUITS. If IAC motor operates as specified, perform TEST TC-138B: TARGET IDLE NOT REACHED.
Condition required to set DTC is not present at this time. TARGET IDLE NOT REACHED DTC sets if PCM senses target idle is not within -100 or +200 RPM of target idle for 14 seconds. Possible causes are: IAC driver circuit shorted to ground, IAC driver circuit shorted to battery, IAC driver circuits shorted together, defective PCM, IAC motor shorted internally, carbon deposits, open driver circuit, defective connector terminals or connector wires. Go to next step.
Inspect all related wiring and connectors. Repair wiring and connectors as necessary and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies. If wiring and connectors are okay, go to next step.
Start engine. Using scan tool, actuate IAC wiggle test. Idle Air Control (IAC) motor should raise and lower idle speed with scan tool display. If IAC motor does not operate as specified, perform TEST TC-25A: IDLE AIR CONTROL MOTOR CIRCUITS. If IAC motor operates as specified, go to next step.
Wiggle wiring harness from IAC motor to PCM. Observe for IAC motor to stop operating. If IAC motor stops operating, repair harness where wiggling caused motor to stop and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies. If IAC motor continues to operate, go to next step.
Stop IAC motor wiggle test. See INACTIVE DTC CONDITION. Test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body

TEST TC-138B: TARGET IDLE NOT REACHED
NOTE:For connector terminal identification, see CONNECTOR IDENTIFICATION. For component location and wiring diagram, see WIRING DIAGRAMS article.

Turn ignition off. Disconnect PCV valve hose from intake manifold. Cap vacuum port at intake manifold. Disconnect idle purge hose from throttle body. Install Orifice Tool (6714) on idle purge hose port at throttle body. Go to next step.
Start engine. Allow engine to reach operating temperature. Using scan tool, actuate MIN AIRFLOW. If engine speed is 550 RPM or more, replace throttle body and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies. If engine speed is less than 550 RPM, go to next step.
WARNING:Clean throttle body in well ventilated area and wear rubber gloves.

Remove throttle body. While holding throttle open, spray entire throttle body bore with carburetor/throttle body cleaner. Using soft scuff pad, clean throttle body bore and throttle plate. Using compressed air, dry throttle body. Install throttle body and go to next step.
Start engine. Allow engine idle to stabilize. Using scan tool, actuate MIN AIRFLOW. If engine speed is less than 550 RPM, replace throttle body and perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies. If engine speed is 550 RPM or more, test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES on AB body, or TEST VER-2A: ROAD TEST VERIFICATION on all other bodies.
NOTE:A break in test sequence occurs at this point. Sequence skips from TEST TC-138B to TEST TC-140A. No tests have been omitted.
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Friday, February 18th, 2011 AT 12:36 AM

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