Hi new to the forum. Looking at buying a bronco from a co-worker. Its a 94 with the 302. The fuel pump went out on it. Changed the one on the tank. Now when the truck is idling it drops really low like it will quit then comes back and does it again for a min then resumes to normal only to happen again. What do you think the problem would be?? thanks for your help.
Idle droping
- Thread starter mnklitzke
- Start date
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yo
Need to check for Trouble Codes to confirm this guess; IAC...
Self Test by our pal, BroncoJoe19
Remember to have engine @ Normal Operating Temperature before doing the KOER portion
If the DTC indicates the IAC; inspect connector to ensure it is plugged in/not corroded, etc. btw, replaced my IAC last weekend; had long crank times (combined with a dead cell in batty.. typical double trouble!)
IAC Quick Test with VOM;
Make sure the ignition key is OFF .
Disconnect the air control valve.
Use an ohmmeter to measure the resistance between the terminals of the valve solenoid.
Due to the diode in the solenoid, place the DVOM positive lead on the VPWR pin (RED WIRE) and the negative lead on the ISC pin.
If the resistance is not 7-13 ohms replace the air control valve.
Idle or Stalling Problems & Troubleshooting; "...The IAC is a cylindrical unit attached to the upper intake manifold. This unit electrically controlled by the computer, and allows air to flow into the intake at idle, bypassing the throttle plate. The extra air is accompanied by extra fuel to bring the idle up to proper speed, and when cold, allows a high idle condition. These units may become dirty, and need cleaning. Many idle and stalling issues tend to be blamed on these units. Cleaning is achieved by removing the electrical connector, and two screws holding it on. Once off of the vehicle, clean with throttle body cleaner (or a good carburetor cleaner). Continue cleaning until unit is clean, like new; reinstall unit. This is also a good time to clean the intake, and EGR ports (if applicable). Testing may be achieved by bringing the engine to operating temperature, noting the idle speed (should be within spec). Unplug the unit
Need to check for Trouble Codes to confirm this guess; IAC...
Self Test by our pal, BroncoJoe19
Remember to have engine @ Normal Operating Temperature before doing the KOER portion
If the DTC indicates the IAC; inspect connector to ensure it is plugged in/not corroded, etc. btw, replaced my IAC last weekend; had long crank times (combined with a dead cell in batty.. typical double trouble!)
IAC Quick Test with VOM;
Make sure the ignition key is OFF .
Disconnect the air control valve.
Use an ohmmeter to measure the resistance between the terminals of the valve solenoid.
Due to the diode in the solenoid, place the DVOM positive lead on the VPWR pin (RED WIRE) and the negative lead on the ISC pin.
If the resistance is not 7-13 ohms replace the air control valve.
Idle or Stalling Problems & Troubleshooting; "...The IAC is a cylindrical unit attached to the upper intake manifold. This unit electrically controlled by the computer, and allows air to flow into the intake at idle, bypassing the throttle plate. The extra air is accompanied by extra fuel to bring the idle up to proper speed, and when cold, allows a high idle condition. These units may become dirty, and need cleaning. Many idle and stalling issues tend to be blamed on these units. Cleaning is achieved by removing the electrical connector, and two screws holding it on. Once off of the vehicle, clean with throttle body cleaner (or a good carburetor cleaner). Continue cleaning until unit is clean, like new; reinstall unit. This is also a good time to clean the intake, and EGR ports (if applicable). Testing may be achieved by bringing the engine to operating temperature, noting the idle speed (should be within spec). Unplug the unit
